msc.procor 2006 user's guide

MSC.ProCOR 2006

User’s Guide

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The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein.

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C O N T E N T SMSC.ProCOR User’s Guide

1Overview � Introduction, 8

� How MSC.ProCOR Works, 9❑ Modal Effective Mass (MEM), 11❑ Modal Effective Reaction (MERXN), 12❑ Kinetic Energy Fraction (KE), 13❑ Drive Point Residue (DPR), 14❑ Cross Orthogonality (Ortho), 15❑ Modal Assurance Criteria (MAC), 16

� References, 18

2Using MSC.ProCOR

� Starting MSC.ProCOR, 20❑ Typical usage for Pre-test GSET model:, 21❑ Typical usage for Pre-test ASET model:, 22❑ Typical Universal file UFF Utilities usage:, 22❑ Typical usage for Post-test ASET model:, 23❑ Typical usage Model to Model setup, 24❑ Aset Utilities, Results Tools, and MEM, ORTHO, MAC access., 25

� Analysis Setup Form, 26❑ Pre-Test GSET Analysis Setup, 27❑ Pre-Test ASET Analysis Setup, 29❑ Post-Test ASET Analysis Setup, 31❑ MSC.Nastran DB/PARAM/OUTPUT Options, 33❑ Analysis Setup Usage Notes, 34

� OUTPUT2 Read Special, 36

� Drive Point Residue Calculation, 39

� Kinetic Energy Table, 41

� Group Energy Table, 43❑ Kinetic Energy, 44❑ Element Strain Energy, 48

� MEM, Ortho, MAC, 50❑ Mode Filtering--Select Modes, 51

❑ Mode Filtering--Match Modes, 52❑ Typical Output, 53❑ Usage Notes, 55

� Spike Plot, 57

� Aset Utilities, 59❑ ASET Name Options, 59❑ Add/Modify dof, 60❑ Delete dof, 61❑ Display Options, 62❑ Verify, 63❑ Write File / Read File, 64

� Animate Special, 65

� Re-phase Results, 68

� UFF Utilities, 69❑ Geometry Match, 69❑ Translate Test Data, 74

� Generate Reduced Model, 79

� BDF Match Utility, 82

� Model Comparison Setup, 88

3Examples � Example 1 - GSET Model, 95

❑ Build the Model, 96❑ Enable MSC.ProCOR, 98❑ Set Up the GSET Run, 98❑ Set GSET DB/PARAM/Output Options, 100❑ Inspect the GSET Analysis Setup, 102❑ Submit the GSET Analysis, 103❑ Calculate Center of Gravity, 104

� Example 2 - GSET Model Results, 106❑ Read Results, 106❑ Display Mode Shapes , 107❑ Display Modal Effective Mass (MEM), 109❑ Display Modal Effective Reactions (MEFFRXN), 112❑ Report Kinetic Energy (KE), 115❑ Spike Plots of Eigenvectors, KE, and DPR, 117❑ Display and Report Group Kinetic Energy (KE), 118❑ Report Group Element Strain Energy (ESE), 123❑ Calculate Drive Point Residues (DPR), 125

� Example 3 - ASET Selection and Model Setup, 128

❑ ASET Selection, 128❑ Create the Traceline, 130❑ Set Up the ASET Run, 135❑ Inspect the ASET Analysis Setup, 138❑ Submit the ASET Analysis, 139

� Example 4 - Views and Group Setup, 140❑ Create Multiple Viewports, 140❑ Create Groups for Results Posting, 141❑ Color Selection, 144

� Example 5 - ASET Model Results, 145❑ Read Results, 145❑ Display Mode Shapes, 146❑ Display Modal Effective Mass (MEM), 150❑ Display Orthogonality/MAC Results (ORTHO/MAC), 153❑ Spike Plots of Eigenvectors, KE, and DPR, 157❑ Group Energy Calculations, 157❑ Animate Different Modes in Different Viewports, 157❑ ASET Conclusion, 159

� Example 6 - Translate Test Data, 161❑ Set Up Test Data Translation, 161❑ Submit the MSC.Nastran Translation Run, 162❑ Add Frequency Labels, 162

� Example 7 - Test/Analysis Correlation, 164❑ Set Up the Test/Analysis Run, 164❑ Inspect the Post-test ASET Analysis Setup, 166❑ Submit the Post-test ASET Analysis, 167❑ Read Results, 168❑ View Correlation Matrices, 169

� Example 8 - Model Updates, 173❑ Modify Properties, 173❑ Delete Results Cases, 173❑ Re-submit the Test/Analysis Correlation Job, 174❑ Re-read Output Results, 174❑ Review Correlation Matrices, 175❑ Bad Accelerometer Data, 176

� Example 9 - Model-Model Comparison - Take 1, 178❑ Create Coarse Meshed Model, 178❑ Generate ASET, 179❑ Generate PLOTELs, 180❑ Determine the Center of Gravity, 181❑ Generate Reduced Model, 182❑ Inspect the Reduced Model Analysis Setup, 184❑ Submit the Model Reduction Analysis, 184

❑ Generate Fine Meshed Model, 185❑ Map the Course Mesh to the Fine Mesh, 186❑ Determine Center of Gravity of Fine Meshed Model, 191❑ Set Up Model Comparison Analysis, 192❑ Inspect the Model Comparison Analysis Setup, 196❑ Submit the Model Compare Analysis, 197❑ Read Output Results, 197❑ Display MEM, ORTHO, MAC Matrices, 198

� Example 10 - Model-Model Comparison - Take 2, 200❑ Create Preliminary Model, 200❑ Generate Baseline Modes, 202❑ Inspect the Baseline Analysis Setup, 204❑ Submit the Baseline Analysis, 205❑ Modify Existing Model, 205❑ Set Up Model Comparison Analysis, 207❑ Inspect the Model Comparison Analysis Setup, 209❑ Submit the Model Compare Analysis, 210❑ Read Output Results, 210❑ Display MEM, ORTHO, MAC Matrices, 211

� Example 11 - Universal File Translation, 212❑ Create the Analytical Model, 212❑ Map the Test Model Information to the Analytical Model, 213❑ Run the Pre-test GSET Analysis, 219❑ Run the Pre-test ASET Analysis, 220❑ Translate the Test Modes from the Universal File, 220❑ Run the Post-test ASET Analysis, 220

MSC.ProCor 2003 User’s Guide

1 Overview

� Introduction

� How MSC.ProCOR Works

� References

8

1.1 IntroductionMSC.ProCOR is a professional modal correlation tool for use with finite element (FE) models and modal test data, or between two different FE models. With MSC.ProCOR analysts can ensure that their FE models more closely match reality by correlating them to modal test data acquired from fully instrumented test articles, thus giving confidence in any subsequent analyses using the FE model. Modal correlation between two similar models can provide the critical assessments needed to determine if a more costly dynamic analysis needs to be re-performed as designs mature.

The purpose of this manual is to provide the user with the knowledge and information needed to properly and effectively use this product to correlate FE models to test data. Typical example problems are included to show software usage and provide helpful hints to maximize its usefulness to the user. Each example is designed to show certain aspects and help to convey various principles of test-analysis correlation. The intent is to get users up to speed as quickly as possible without a steep learning curve.

9CHAPTER 1Overview

1.2 How MSC.ProCOR WorksMSC.ProCOR is an analytical tool for performing mathematical modal correlation of eigenvectors between two different sources. MSC.ProCOR is a graphical interface within MSC.Patran to correlate either:

• Two different analytical models

• An analytical model with corresponding test data

MSC.ProCOR modifies, marries, and exploits existing open architecture technology within MSC.Patran and MSC.Nastran to provide a comprehensive suite of correlation tools using:

• MSC.Nastran: DMAP Alters

Used as a mechanism to alter the solution sequence and perform additional calculations in support of correlation for modal analysis using MSC.Nastran Solution 103.

• MSC.Patran: PCL

The mechanism to graphically interface with the FE model for analysis set-up, and post processing correlation exercises.

Correlation is done with the help of various calculated quantities. These quantities consist of:

1. Modal Effective Mass (MEM) -- Identifies dominant structural modes of the FE model by amount of mass contribution from each mode.

2. Modal Effective Reaction (MERXN) -- Identifies dominant structural modes of the FE model by identifying modes contributing to interface loads (reaction loads).

3. Kinetic Energy (KE) -- Identifies candidate accelerometer locations.

4. Drive Point Residue (DPR) -- Identifies candidate locations for shakers; can also be used to identify candidate accelerometer locations.

5. Cross orthogonality --A quantitative measure of correlation using the mass matrix.

6. Modal Assurance Criteria (MAC) --A quantitative measure of correlation without using the mass matrix.

A typical scenario might be:

A company wishes to produce an accurate FE model of a launch system (rocket) for boosting a satellite into orbit. A preliminary FE model of the satellite has been provided by an outside vendor and mathematically coupled onto the FE model of the

10

launch system. The launch system FE model must be accurate for proper load prediction and load transfer into the satellite. This information must be provided back to the satellite manufacturer so that the satellite can be designed to the correct load levels.

With this goal in mind, a full-size prototype of the launch vehicle is produced and placed in a test laboratory. In order for the test to be successful, two preliminary pieces of information need to be ascertained from the unconstrained FE model (sometimes referred to as the pre-test model): accelerometer locations and shaker locations. In other words, where should measurements be taken to properly capture the dynamics of the vehicle, and where should the vehicle be dynamically loaded such that the full range of dynamics is excited? This is what a pre-test model analysis provides by looking at the predicted analytical mode shapes and: quantifying modal dominance (MEM, MERXN) to determine target modes, calculating kinetic energy (KE) for aid in determining accelerometer locations, and calculating drive point residues (DPRs) for identifying candidate shaker locations.

Once the prototype is instrumented and the first bit of data captured, the test mode shapes are used to validate the reduced FE model. Since many more locations are available in an FE model than are possible to instrument on the prototype, the FE model is reduced to the size of the instrument locations.

The full size FE model is referred to as the g-set (GSET), signifying all structural grid point degrees-of-freedom. The reduced set is referred to as the a-set (ASET), or assembled set of degrees-of-freedom. The GSET and ASET usage is terminology used in MSC.Nastran. There are also a number of other sets such as the o-set (omitted set), the m-set (multi-point constraint set), the s-set (single point constraint set), the n-set (not constrained by multi-point constraints), and the f-set (unconstrained or free). The relation between these is as follows:

g-set=m-set+n-setn-set=s-set+f-setf-set=a-set+o-set

The ASET can also be subdivided also, but this is beyond the scope of this explanation. All that is used in test-analysis correlation are the ASET and GSET. The GSET model is reduced to the ASET size by a technique called Guyan reduction. The integrity of the ASET model is determined by a triple matrix product of the GSET modes, ASET (reduced) mass matrix, and the ASET modes. This is called an orthogonality check which should produce an identity matrix if the reduction is perfect. The degree that the off-diagonal terms are not zero is an indication of the quality of the reduced model size. Unsatisfactory orthogonality checks at this point generally require that more measurement locations be selected.

Other checks are performed (orthogonality and modal assurance criteria) once test data has been acquired to determine the degree of correlation between the test and analytical models. Again these checks result in identity matrices for fully correlated models. Criteria is set for the degree that diagonal terms may deviate from unity and

11CHAPTER 1Overview

off-diagonal terms may deviate from zero. If the criteria is not met then the analytical model must be modified and updated (assuming the test data is correct) and the correlation checks redone. This of course is often the difficult part of correlating a model to test data and mostly requires good engineering judgement and perhaps a great deal of experience to pinpoint the problem areas. Many times this is done manually or with optimization programs such as MSC.Nastran SOL 200.

Once the correlation criteria has been satisfied the launch vehicle model can be used with confidence in a coupled analysis with the FE satellite model. Load information can be relayed back to the satellite supplier who can make any necessary changes to their structural FE model (which may also have a modal test/analysis correlation done).

Modal Effective Mass (MEM) Modal Effective Mass (MEM) is a measure of the amount of mass which is participating in each mode. A participation factor is calculated as [Ref 1.]:

Eq. 1-1

where is a set of flexible mode shapes an is a set of rigid body mode shapes.

The participation factors are better interpreted by calculating the Modal Effective Mass which is:

Eq. 1-2

where indicates a term-by-term multiplication.

The modal effective weight (MEW) is calculated by taking the modal effective mass and multiplying by the acceleration due to gravity (g).

A more useful way to view MEM is by the percent (MEM%) as in the following equation:

Eq. 1-3

where i is a column corresponding to each degree-of-freedom: Tx, Ty, Tz, Rx, Ry, or Rz

Γ Φ{ }TM Φrb{ }=

Φ{ } Φrb{ }

MEM Γ Γ⊗=

⊗

EMΓi Γi⊗[ ]

Φrb{ }TM Φrb{ }[ ]

i

--------------------------------------------------------- 100×=

12

Dominant modes are identified easily when the MEM% table is reviewed. MSC.ProCOR displays a formatted table and/or 3D bar chart plot of the MEM%.

MSC.ProCOR reports the MEM% for each mode. The following MEM%'s are calculated:

• MEMG -- The MEM% of the GSET modes. This is useful in identifying target modes for a test, or identifying modes which are critical to the overall response of the structure.

• MEMA -- The MEM% of the ASET modes. The ASET mass matrix is used in the calculations. Significant variations from MEMG may indicate a loss of fidelity during the ASET reduction.

• MEMT -- The MEM% of the Test modes. Note that the ASET analytical mass matrix is used in the calculations. Thus, it is possible to compute a total MEM% greater than 100%. Deviations for m the FE MEM can indicate either an inadequate FE model, or analytical mass matrix, or both.

MSC.ProCOR also computes a total MEM% for the number of modes selected. This is useful in determining whether a significant portion of the mass in a specific direction is captured in the retained modes.

As an example, a cantilever beam will contain a large percent of the transverse and rotational modal effective mass in the first few flexural modes, but the axial MEM will not be significant until the first axial mode is excited which is usually a significantly higher frequency than the flexural modes.

Modal Effective Reaction (MERXN) Modal Effective Reactions (MERXNs) are a cousin to MEM. However, instead of the rigid body modes, constraint modes are used. Constraint modes are formed by:

Important: Usage notes:

• The flexible modes, , must be scaled to the model mass by using mass normalization (default) on the MSC.Nastran EIGR and/or EIGRL entries. In MSC.Patran this is found under the Analysis | Subcase Create | Subcase Parameters form.

• The rigid body modes, and rigid body mass matrix [M],

should be calculated using the center of gravity of the structure. This is done by placing a constrained dummy grid at center of mass then using the PARAM,GRDPNT,cmgridid entry in the MSC.Nastran input file. This is done under Analysis | Solution Type | Solution Parameters in MSC.Patran.

Φ{ }

Φrb{ }

13CHAPTER 1Overview

Eq. 1-4

The participation factor becomes:

Eq. 1-5

And the Modal Effective Reaction (MERXN) is calculated similarly to MEM. This is a relatively expensive calculation because of the expense involved in calculating the constraint modes. Thus, the analyst should use this calculation sparingly. It is recommended to perform this only on the unreduced GSET model. There will be no difference if done on the ASET model because the FSET is formed prior to the ASET.

Kinetic Energy Fraction (KE)The KE fraction is defined as [Ref 1.]:

Eq. 1-6

where are eigenvectors (mode shapes) and is the mass matrix.

MSC.Nastran DMAP alters used by MSC.ProCOR manipulate the equation to retain the sign of in . Also note that the raw number can be difficult to interpret, so MSC.ProCOR normalizes this such that, at the GSET level:

Eq. 1-7

where is the kinetic energy fraction for mode i.

The is often used as an “accelerometer” location indicator or selector in pretest analysis. Traditionally, locations of high kinetic energy are used as accelerometer locations.

Equally important is the test/analysis comparison of because of its relation to the cross orthogonality matrix. Degrees-of-freedom with relatively large will influence the cross orthogonality matrix the most.

MSC.ProCOR calculates the for GSET modes, ASET modes, and Test modes. These are treated as any other nodal vector quantity and spike plots and vector plots can be useful in determining locations of high kinetic energy.

Φcm{ } Kff[ ] 1–Kfs[ ]–=

Γ Φ{ }TM Φcm{ }=

KE{ } Φ{ }TM{ } Φ{ }⊗( )=

Φ{ } M[ ]

Φ{ } KE{ } KE{ }

KEi{ }∑ 100%=

KEi{ }

KE{ }

KE{ }KE{ }

KE{ }

14

MSC.ProCOR also has special forms for calculating the for user defined groups in the form of summary tables and vector plots. For example, detailed models of components (i.e., electronics boxes) might have a small kinetic energy fraction for each individual node, but the collective for the component may be a significant percentage for a specific mode, indicating that an accelerometer should be placed somewhere in that group.

Drive Point Residue (DPR)The Drive Point Residue (DPR) is a calculated quantity which gives an indication which degree-of-freedom points on the model are best suited for placing shakers [Ref 5.].

For an individual mode, engineering judgment can usually be used for choosing drive point locations with reasonable results. During testing, it would be impractical to move the shaker around the structure to drive each individual mode, so reducing the number of shaker locations to 1 or 2 is highly desirable. For most structures there is usually more than one mode of interest. Determining a single best location for shaker excitation becomes difficult to determine by engineering judgment, and time consuming in the lab without prior analysis. Thus, taking the DPRs for each mode and performing algebraic manipulation, the best candidate excitation location(s) become clear.

Eq. 1-8

where is the drive point residue vector for mode i, is the eigenvector of mode i, and is the circular frequency of mode i.

Once the DPRs of each mode are calculated, then algebraic manipulations can be performed to provide data to the engineer. For a selected subset of computed modes (or, all the modes), a maximum, minimum, average, and weighted average calculation of DPR can be performed.

• The maximum and minimum DPRs are simply a maximum or minimum search over all the modes of interest.

• The average DPR is simply a summation of DPRs for all modes divided by the number of modes.

• The weighted average DPR is the average DPR times the minimum DPR.

The weighted average is probably the most useful quantity because it will filter out degrees of freedom which have low modal displacements in one or more modes (i.e. filters out degrees of freedom which are on a node line for a mode of interest).

Note: DPRs can also be used as an indicator for accelerometer locations.

KE{ }

KE{ }

DPRi{ } Φi{ } Φi{ } ωi⋅⊗=

DPRi{ } Φi{ }ωi

15CHAPTER 1Overview

MSC.Nastran is used to calculate DPRs for each mode. MSC.ProCOR forms within MSC.Patran are used to calculate the combinations based on the user selected modes of interest. The weighted average DPRs can then be used in contour plots, spike plots, vector plots, and other assorted visual aids to determine potential drive point locations.

Cross Orthogonality (Ortho)The Cross Orthogonality (Ortho) is a measure of the mathematical orthogonality of two sets of eigenvectors with respect to the mass matrix. By definition, the eigenvectors computed by MSC.Nastran are orthogonal when normalized to the mass matrix. The cross orthogonality matrix is defined as [Ref 2.][Ref 3.]:

Eq. 1-9

where and are eigenvectors and is a mass matrix. Usually is an analytical mass matrix related to either or . A perfectly orthogonal set of eigenvectors will produce the identity matrix.

MSC.ProCOR calculates several different cross orthogonality matrices; the meaning and interpretation of these is as follows:

Eq. 1-10

where are the GSET eigenvectors (partitioned to ASET size), is

the ASET mass matrix, and are the ASET eigenvectors. If the ASET is a

good representation of the GSET, then will be identity. If modes

are not retained in the ASET model, then a non-diagonal matrix will result.

Eq. 1-11

where are the GSET eigenvectors (partitioned to ASET size), is

the ASET mass matrix. If the ASET is a good representation of the GSET, then

will be identity. By default, the diagonal terms will be 1.0. Off-

diagonal terms may indicate a problem in the mass reduction. If this occurs, either more points are required in the ASET, or a better distribution is required.

Eq. 1-12

OrthoAB[ ] ΦA{ }TMxx ΦB{ }=

ΦA{ } ΦB{ } Mxx[ ] Mxx[ ]ΦA{ } ΦB{ }

OrthoGA[ ] ΦG{ }TMAA ΦA{ }=

ΦG{ } MAA[ ]

ΦA{ }

OrthoGA[ ]

OrthoGG[ ] ΦG{ }TMAA ΦG{ }=

ΦG{ } MAA[ ]

OrthoGA[ ]

OrthoTA[ ] ΦT{ }TMAA ΦA{ }=

16

where are the Test mode shapes (partitioned to ASET size), is

the ASET mass matrix, and are the ASET eigenvectors. This is the matrix most used to determine correlation of an analytical model to test data. A typical criteria for “correlation” requires that the diagonal terms of

be >0.9 and the off-diagonal terms be < 0.1. Often, a more

stringent criteria may be placed on modes with high MEM or MERXN because these modes can affect the global dynamic response the most. Likewise, less stringent criteria may be applied to modes with less MEM or MERXN, higher order modes, or modes above a certain frequency threshold.

Eq. 1-13

where are the Test mode shapes (partitioned to ASET size),

and is the ASET mass matrix. Because the test mode shapes are

normalized to the ASET mass matrix, the diagonals of this matrix will be 1.0; the off-diagonal terms are the terms of interest. A poor matrix indicates potential problems with the ASET mass matrix, or non-orthogonal test modes.

Eq. 1-14

where are the model 1 eigenvectors (normalized to ), is the

ASET mass matrix of model 2, and are the model 2 eigenvectors.

Eq. 1-15

where are the model 2 eigenvectors (normalized to ), is the

ASET mass matrix of model 1, and are the model 1 eigenvectors.

Modal Assurance Criteria (MAC)Modal Assurance Criteria (MAC) is a measure of the independence of one eigenvector, with respect to another . In dynamics, and are a complete set of eigenvectors for a given model or mode shapes for test data.[Ref 2.][Ref 4.].

ΦT{ } MAA[ ]

ΦA{ }

OrthoTA[ ]

OrthoTT[ ] ΦT{ }TMAA ΦT{ }=

ΦT{ }MAA[ ]

Ortho12[ ] Φ1{ }TM22 Φ2{ }=

Φ1{ } M22[ ] M22[ ]

Φ2{ }

Ortho21[ ] Φ2{ }TM11 Φ1{ }=

Φ2{ } M11[ ] M11[ ]

Φ1{ }

Φi{ } Ψj{ } Φi{ } Ψj{ }

17CHAPTER 1Overview

Eq. 1-16

Two eigenvectors which are perfectly correlated will have a MAC of 1.0; two which are perfectly independent will have a MAC of 0.0. Thus, the full MAC matrix should be the identity matrix for two different sets of eigenvectors of a perfectly correlated model.

MSC.ProCOR calculates several different MACs. The meaning and interpretation of these is as follows:

• MACGA --MAC comparison of the full model (GSET) eigenvectors with the reduced model (ASET) eigenvectors.

• MACTA--MAC comparison of the Test mode shapes with the reduced (ASET) model eigenvectors.

• MACTT --MAC comparison of the Test mode shapes with Test mode shapes. Inspection of the MAC equation indicates that when i=j, the MAC will be 1.0 by definition. Thus, for MACTT, the off-diagonal terms are the indicators of correlation.

• MAC12 -- MAC comparison of model 1 eigenvectors with model 2 eigenvectors.

MACij

Φi{ }T Ψj{ }[ ]2

Φi{ }T Φi{ }[ ] Ψj{ }T Ψj{ }[ ]------------------------------------------------------------------------=

18

1.3 References

1. Rose, Ted L., “Using Superelements to Identify the Dynamic Properties of a Structure,” The MSC 1988 World Users Conf. Proc., Vol. 1, Paper 41, March 1988.

2. Blakely, Ken, and Rose, Ted, “Cross-Orthogonality Calculations for Pre-Test Planning and Model Verification,” The MSC 1993 World Users Conf. Proc., Vol. 1, Paper 72, May, 1993.

3. MSC.Nastran Dynamic Analysis Seminar Notes, The MacNeal-Schwendler Corporation, Los Angeles, CA, September, 1994.

4. Ting, T, Chen, T.L.C, and Twomey, W., “Correlating Mode Shapes Based on Modal Assurance Criterion,” The MSC 1992 World Users Conf. Proc., Vol. 1, Paper 21, May, 1992.

5. Kientzy, Donald; Richardson, Mark; and Blakely, Ken, “Using Finite Element Data to Set Up Modal Tests,” Sound and Vibration, June, 1989, pp 16-23.


2 Using MSC.ProCOR

n Starting MSC.ProCOR

n Analysis Setup Form

n OUTPUT2 Read Special

n Drive Point Residue Calculation

n Kinetic Energy Table

n Group Energy Table

n MEM, Ortho, MAC

n Spike Plot

n Aset Utilities

n Animate Special

n Re-phase Results

n UFF Utilities

n Generate Reduced Model

n BDF Match Utility

n Model Comparison Setup

20

2.1 Starting MSC.ProCORTo run MSC.ProCOR after a successful installation, invoke MSC.Patran. MSC.ProCOR is accessed under the Tools menu after a database has been opened..:

The MC.ProCor main menu is organized into logical tasks, and appropriate buttons are available for each task.

Note that many of the submenus contain links to the same modules or forms. This is done to allow access to the same functions within logical blocks as required by data flow and for convenience’s sake.

As an example, Aset Utilities is available from the MSC.ProCOR main menu, Pretest ASET..., Posttest ASET..., and the Model to Model... submenus.

The menus are setup in the logical manner in which a user would approach test/analysis and model/model comparison. Usage examples are shown below.

21CHAPTER 2Using MSC.ProCOR

Typical usage for Pre-test GSET model:

1. Analysis Setup Form (page. 26) - create MSC.Nastran input file for GSET model and run job.

2. OUTPUT2 Read Special (page. 36) - read results from OUTPUT2 files into MSC.Patran database.

3. MEM, Ortho, MAC (page. 50) - perform modal effective mass (MEM) and modal effective reaction (MERXN) calculations on GSET model to determine major modal contributions.

4. Look at other pre-test results to make decisions on test setup such as accelerometer and shaker locations - Drive Point Residue Calculation (page. 39), Kinetic Energy Table (page. 41), Group Energy Table (page. 43), Spike Plot (page. 57), Re-phase Results (page. 68), Animate Special (page. 65).

Pretest GSET Options

22

Typical usage for Pre-test ASET model:

1. Aset Utilities (page. 59) - create ASET for pre-test ASET model.

2. Analysis Setup Form (page. 26) - create MSC.Nastran input file for pre-test ASET model and run job.


4. MEM, Ortho, MAC (page. 50) - perform modal effective mass (MEM), orthogonality and MAC calculations on ASET model to determine validity of reduced model.

5. Look at other results - Drive Point Residue Calculation (page. 39), Kinetic Energy Table (page. 41), Group Energy Table (page. 43), Spike Plot (page. 57), Re-phase Results (page. 68), Animate Special (page. 65).

Typical Universal file UFF Utilities usage:

1. Geometry Match (page. 69) - read coordinate systems, nodes, trace lines and ASET information from a test-based Universal file. Map this information to that of the analytical model stored in the MSC.Patran database and display tracelines between the measurement (or ASET) locations for display purposes.

2. Translate Test Data (page. 74) - take test mode shape information from a Universal (or OUTPUT4) file and convert it to DMIG format (modes) and DMI format (frequencies) for later use in test/analysis correlation. Ensure that the information maps to the analytical model.

Pretest ASET Options

Uff Utilities Options


Typical usage for Post-test ASET model:

1. Aset Utilities (page. 59) - create or modify ASET for post-test ASET model.

2. Analysis Setup Form (page. 26) - create MSC.Nastran input file for post-test ASET model, associating the test information such that correlation matrices can be created and run job.


4. MEM, Ortho, MAC (page. 50) - perform modal effective mass (MEM), orthogonality and MAC calculations on ASET model to determine correlation of analytical model to test. Also determine validity of test data.

5. Look at other results - Drive Point Residue Calculation (page. 39), Kinetic Energy Table (page. 41), Group Energy Table (page. 43), Spike Plot (page. 57), Re-phase Results (page. 68), Animate Special (page. 65).

Posttest Aset Options

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Typical usage Model to Model setup

1. Aset Utilities (page. 59) - create ASETs for model reduction purposes.:

2. Generate Reduced Model (page. 79) - create MSC.Nastran input file for model reduction to mass and stiffness or mass and mode shape representation.

3. BDF Match Utility (page. 82) - read coordinate systems, nodes, and trace line (PLOTELs) information from a MSC.Nastran bulk data. Map this information to that of the current analytical model stored in the MSC.Patran database and display tracelines (PLOTELs) between the corresponding (ASET) locations for display purposes. Ensure proper map between matching model locations.

4. Model Comparison Setup (page. 88) - create MSC.Nastran input file for model comparison between the two analytical models run job. Select between internal MSC.Patran database model and external matrix representations of analytical model.


6. MEM, Ortho, MAC (page. 50) - perform modal effective mass (MEM), orthogonality and MAC calculations to determine correlation of analytical models.

Model to Model Options


Aset Utilities, Results Tools, and MEM, ORTHO, MAC access.These tools are all available in this menu as well as from the other menus shown above. This is done for convenience in working with MSC.ProCOR once you become proficient.

Frequency Define

These tools can be used to create or modify frequencies for model-test or model-model correlation. Normally, this tool is not required.

Clean up 3D Bar Chart

If a 3D bar chart (MEM, ORTHO, MAC) is not canceled when prior to closing the database, this option will remove the window and extra graphics items associated with the 3D bar chart.

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2.2 Analysis Setup FormThis form can be accessed from either the Pretest GSET..., the Pretest ASET..., or the Posttest ASET... buttons.

This utility sets up all the forms in the Analysis application appropriately for each analysis run type. Without this utility, the setup for each run would become tedious to the point of frustration. It also eliminates the need to edit the MSC.Nastran bulk data after it has been written allowing the user to create and submit run-ready input files.

The features of this form are described below and over the next few pages. Depending on the Run Type, various options are presented to the user.

MSC.Nastran DB/PARAM/OUTPUT Options (page. 33) will help users define the most commonly modified parameters used by MSC.Patran MSC.ProCOR when submitting MSC.Nastran jobs.


Pre-Test GSET Analysis SetupUsage of this form will automatically set up an MSC.Nastran job called pre-g which is representative of the entire model or GSET.


Reduction Method: A Guyan (ASET) reduction is possible even at the GSET level. Typically, “None” should be selected.

G Mode Output: Mode shape output for orthogonality checks is written to either an MSC.Nastran OUTPUT4 file (binary) or to MSC.Nastran PUNCH file in DMIG card image format (ASCII). The default OUTPUT4 file is pre-g.phg and may be changed; the PUNCH file is pre-g.pch and may not be changed. Usage of OUTPUT4 files is recommended.

When the Apply button is pressed, this form closes and the Analysis application is automatically invoked ready to submit the newly created pre-g job. The Analysis Preference must be set to MSC.Nastran for this to work properly. The pre-g job is automatically configured with the following:

1. Translation Parameters...

Automatically offsets subcase number (required)

2. Solution Type...

Solution type is set to Normal Modes (SOL 103). No solution parameters are modified. See Analysis Setup Usage Notes (page. 34).

3. Direct Text Input...

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OUTPUT2 and OUTPUT4 files are assigned in the FMS section. DMAP alters are placed in EXEC deck. Certain parameters are set in the CASE control. And DTI (direct table input) cards are placed in BULK data section for proper handshaking between MSC.Nastran and MSC.ProCOR.

4. Subcase Create...

A subcase called pre-g is created which uses a load case called pre-g. This subcase is a copy of the MSC.Patran default subcase. If a different set of boundary conditions is desired, it will have to be modified in Load Cases. See Analysis Setup Usage Notes (page. 34).

5. Subcase Select...

The pre-g subcase is associated to the pre-g job.

All of this information can be viewed from the Analysis application if necessary. The created job is “run-ready,” meaning the user may press the Apply button on the Analysis application form without having to modify or add any additional information. It is suggested that the user review the information before submitting the job. If the job name pre-g already exists the user will be prompted for overwrite permission.

Note: On Apply, if the Restart from Database toggle is ON, the user will not be placed in the Analysis application, but instead, a “read-only” restart MSC.Nastran input file will be created. The user will then need to go to the Analysis application and submit the job as an Existing Deck. This operation assumes that the MSC.Nastran database has been saved previously.


Pre-Test ASET Analysis SetupUsage of this form will automatically set up an MSC.Nastran job called pre-a which is representative of the reduced model or ASET corresponding to the measurement locations. Mode shape output from the full model (GSET) is necessary for orthogonality and modal assurance criteria (MAC) checks. This necessitates that the GSET model be run first.


Reduction Method: A Guyan (ASET) reduction is performed, choose the appropriate ASET Name defined in the Aset Utilities (page. 59). Note that Kinetic Energy and Drive Point Residues from the GSET model can be used to help determine appropriate ASET degrees of freedom.

G Mode Input: Mode shape input for orthogonality checks was written by the Pretest GSET run (pre-g). Select the appropriate OUTPUT4 or DMIG (punch) file as output from the GSET run. (Typically, pre-g.phg or pre-g.pch.)

Create UT1/UT2 files is an option that if turned ON will create .ut1/.ut2 files used by SDRC/I-DEAS test modules.

The toggle just below this (Include back expansion) will also include the back expansion matrices from the ASET to the GSET.

When the Apply button is pressed, this form closes and the Analysis application is automatically invoked ready to submit the newly created pre-a job. The Analysis Preference must be set to MSC.Nastran for this to work properly. The pre-a job is automatically configured with the following:

Note: These two toggles are provided as a convenience to test labs which use SDRC/I-DEAS. This is a feature provided at customer request. MSC open architecture allows this interface.

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2. Solution Type...



OUTPUT2 and OUTPUT4 files are assigned in the FMS section. DMAP alters are placed in EXEC deck. Certain parameters are set in the CASE control.ASET entries are put in the BULK data section; DTI (direct table input) cards are placed in BULK data section for proper handshaking between MSC.Nastran and MSC.ProCOR.


A subcase called pre-a is created which uses a load case called pre-a. This subcase is a copy of the MSC.Patran default subcase. If a different set of boundary conditions is desired, it will have to be modified in Load Cases. See Analysis Setup Usage Notes (page. 34).


The pre-a subcase is associated to the pre-a job.

All of this information can be viewed from the Analysis application if necessary. The created job is “run-ready,” meaning the user may press the Apply button on the Analysis application form without having to modify or add any additional information. It is suggested that the user review the information before submitting the job. If the job name pre-a already exists the user will be prompted for overwrite permission.



Post-Test ASET Analysis SetupUsage of this form will automatically set up an MSC.Nastran job called post-a which is representative of the reduced model or ASET corresponding to the measurement locations. Test mode shape output is necessary for orthogonality and modal assurance criteria (MAC) calculations. This requires that the test data be translated first. See Translate Test Data (page. 74). The user must select the MSC.Nastran DMIG card images saved on an ASCII punch file from the test modes translation. The default file extension from the translation is .pch, however it could have been named anything.

Before a successful post-test ASET run can be accomplished, the ASET must be defined and selected. The ASET is defined using the Aset Utilities.

The actual test frequencies corresponding to the test mode shapes must exist in an external file also. If the word UNSELECTED is present, then test mode 1 will be assigned 1.0 Hz, test mode 2 will bee assigned 2.0 Hz, and so on. The file, if it was generated and selected, is created during test data translation in the form of MSC.Nastran DMI card images saved in an ASCII file. The default file extension from the translation is .dmi, however it could have been named anything.

When the Apply button is pressed, this form closes and the Analysis application is automatically invoked ready to submit the newly created post-a job. The Analysis Preference must be set to MSC.Nastran for this to work properly. The post-a job is automatically configured with the following:



2. Solution Type...


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OUTPUT2 and OUTPUT4 files are assigned in the FMS section. DMAP alters are placed in EXEC deck. Certain parameters are set in the CASE control. And DTI (direct table input) cards are placed in BULK data section for proper handshaking between MSC.Nastran and MSC.ProCOR and writes the appropriate ASET entries.


A subcase called post-a is created which uses a load case called post-a. This subcase is a copy of the MSC.Patran default subcase. If a different set of boundary conditions is desired, it will have to be modified in Load Cases.See Analysis Setup Usage Notes (page. 34).


The post-a subcase is associated to the post-a job.

All of this information can be viewed from the Analysis application if necessary. The created job is “run-ready,” meaning the user may press the Apply button on the Analysis application form without having to modify or add any additional information. It is suggested that the user review the information before submitting the job. If the job name post-a already exists the user will be prompted for overwrite permission.



MSC.Nastran DB/PARAM/OUTPUT OptionsGeneral Database/Output Options valid for all Run Types are defined below. Note that most of these options will be automatically filled in based on the previous jobs. For instance, the value of PARAM,GRDPNT will be saved and used as the default on the next analysis.

Save Database for Restart: If “off” then INIT MASTER(S) will be placed in MSC.Nastran input file. This has the same effect as submitting an MSC.Nastran run with SCR=YES. If toggled “on” then the normal defaults for submitting an MSC.Nastran run will be used.

Neutral OP2 files: If “on” then the OUTPUT2 (.op2) files generated by MSC.Nastran will be in neutral format. This is useful for transferring .op2 files across non-binary compatible platforms. (i.e MSC.Nastran run on unix, MSC.Patran run on NT.)

Print Results in .f06: If “on” then results will be print to the .f06 file, otherwise they will be placed on the .op2 file only.

bdf Continuation Markers: If “on” then continuation markers will be print for bulk data entries which require more than one line. It is recommended to leave this “off.”

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Restart from Database: This option will create a “read-only” restart bdf file to restart from an existing database. It assumes that the single point constraint set is SPC=2, no explicit MPC’s and an Eigenvalue extraction METHOD=1 for case control. The user must specify the MSC.Nastran database and the restart filename.

Lanczos Extraction: The user can input the lower and upper frequency range of interest and the number of modes.

Run Method: Full Run, Analysis Deck. Full run will submit an MSC.Nastran job when Apply is pressed on the Analysis form, Analysis Deck will create a “run-ready” MSC.Nastran bdf file.

bdf Echo: None, Sorted, or Unsorted: options for the bdf input echo in the MSC.Nastran .f06 file

bdf format: small field, large field, either: specifies the format of bdf entries.

PARAM,AUTOSPC: YES, NO: defines whether null stiffnesses are automatically reduced.

PARAM, K6ROT: real number: defines plate RZ stiffness value.

Mass Calc.: Lumped Coupled: specifies mass matrix calculation technique

PARAM,WTMASS: real number: value by which to pre-multiply mass terms.

PARAM,GRDPNT: node id: node for which to calculate mass properties. Recommended to use dummy node at CG of model. This will ensure meaningful Modal Effective Mass (MEM) calculations.

KE % Filter: real number: cuttoff for KE % (values less than filter are set to 0.0).

Calc.Mode Eff Rxn: toggle to calculated modal effective reactions.

Use BC’s from Loadcase: This is used for setting up appropriate boundary conditions for the run. By default, the previously defined loadcase will be used.

Analysis Setup Usage NotesFor all analysis setups, the following notes are made:

Solution Parameters

In additon to the MSC.Nastran DB/PARAM/OUTPUT Options (page. 33), it may be necessary or desirous to change certain solution parameters prior to submitting the MSC.Nastran jobs. This is done in the Analysis application under Solution Type | Solution Parameters. Additional quantities of interest might be:

• Maximum run time (TIME=)

• Dynamic reduction options (DYNRED= - not recommended)


MSC.Patran MSC.ProCOR will set the values defined in MSC.Nastran DB/PARAM/OUTPUT Options (page. 33) for these parameters each time the Apply button is pressed on the Analysis Setup form.

SPC Forces

SPC forces (SPCF=) must be an output request if kinetic energy and drive point residues are desired. This is specified under the Subcase Create | Output Requests in the Analysis application. This is automatically set for the user, but must be retained in the subcase output definition. The eigenvectors (displacements) must also be an output request.

Job Submittal

All the analysis setup jobs are created “run-ready” for submittal directly from MSC.Patran via the Analysis application. The user may, if desired, set the Method to Analysis Deck such that only an input file is created with no subsequent job submittal. Manual submittal to MSC.Nastran is then possible.

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2.3 OUTPUT2 Read SpecialThe purpose of this form is to read the various OUTPUT2 files created by the MSC.Nastran runs that are set up via the Analysis Setup Form (page. 26) into MSC.ProCOR. The operation of reading the OUTPUT2 file is special in this case, as opposed to importing OUPUT2 files via the Analysis application, because it recognizes and sets up additional results output not normally read in by conventional means.

This OUTPUT2 read operation completely bypasses that of the Analysis application. In other words the user should only read the OUTPUT2 files via this form when working with MSC.ProCOR models. The following results output is imported:

1. Eigenvectors (mode shapes)

2. Single point constraint forces (SPCFORCEs)

3. Element strain energy (ESE)

4. Any other output type normally supported by MSC.Patran as requested in case control

5. Kinetic Energy (KE)

6. Drive Point Residue (DPR)

The OUTPUT2 files read are based on four different analysis types:

1. Pre-test GSET model (Pre_G)

2. Pre-test ASET model (Pre_A)

3. Post-test ASET model (Post_A)

4. Model to Model comparison (Model_Comp)


The files are created by these various analyses. The file names are automatically assigned with MSC.Nastran FMS statements and must not be changed.

Table 2-1 OUTPUT2 File Names

Analysis Type / File Names Description

Pre-Test GSET Analysis

pre-g.op2 Normal output requests (GSET Eigenvectors, SPCFORCE, ESE, etc.)

pregke.op2 GSET kinetic energy

pregdpr.op2 GSET drive point residue

Pre-Test ASET Analysis

pre-a.op2 Normal output requests (ASET Eigenvectors, SPCFORCE, ESE, etc.)

preake.op2 ASET kinetic energy

preadpr.op2 ASET drive point residue

Post-Test ASET Analysis

post-a.op2 Normal output requests (ASET Eigenvectors, SPCFORCE, ESE, etc.)

postake.op2 ASET kinetic energy

postadpr.op2 ASET drive point residue

posttphi.op2 Test mode shapes (ASET)

posttke.op2 Test kinetic energy

posttdpr.op2 Test drive point residues

Model Comparison Analysis

modl_1_kea.op2 Model 1 kinetic energy (ASET)

modl_1_pha.op2 Model 1 eigenvectors (mode shapes - ASET)

modl_2_kea.op2 Model 2 kinetic energy (ASET)

modl_2_pha.op2 Model 2 eigenvectors (mode shapes - ASET)

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Note: If running MSC.Nastran on a remote system, the user must copy the files back to the exact file names as listed above. If the file systems are binary incompatible, then use the FORM=’FORMATTED’ in the OUTPUT2 ASSIGN statements in the FMS. This is done automatically for the user in the Analysis Setup if the user has turned on the Neutral op2 files toggle.


2.4 Drive Point Residue CalculationThe purpose of this form is to create a new results load case containing the maximum, minimum, average, and weighted average DPRs for the modes shapes of interest. See Drive Point Residue Calculation (page. 39).

1. First select the load case of interest. Only loadcases which have DPR results values will be displayed. (These are automatically created by using the Analysis Setup Form (page. 26) and subsequently on results import using the OUTPUT2 Read Special (page. 36).)

2. Next select all the modes of interest, referred to as Subcase IDs.

3. In the data box at the bottom of the form, enter a new result name of choice.

4. Press the Apply button to create the new Result Case.

In the form displayed above, a new Result Case called DPR_G_1_7 will be created on pressing the Apply button after the modes of interest are selected. The results contained in this new Result Case can then be viewed from the standard Results application. The new result subcases created are:

• Maximum DPR

• Minimum DPR

• Average DPR

• Weighted Average DPR

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These newly created results can be viewed in a variety of ways to help determine the best excitation locations. Perhaps the most useful quantity is the Weighted Average DPR which can be displayed as a fringe plot, a marker plot, or a vector plot. Or the user can use the Spike Plot (page. 57) to display the DPR values.

Note: For structures with well defined modes in a specific direction, multiple DPRs can be calculated. For example a cantilever beam which has “y” motion modes and “z” motion modes, a subset of “y” modes should be selected for one DPR calculation and the “z” modes for the other. In this case, two “best” locations can be selected. A review of the Modal Effective Mass in MEM, Ortho, MAC (page. 50) can be used to help determine modes with similar mass movement (i.e. “y” or “z”).


2.5 Kinetic Energy TableThe purpose of this form is to generate a table of Kinetic Energy. The Kinetic Energy percentage for each degree-of-freedom for each mode is calculated. A filter is provided to limit the output if desired. The Kinetic Energy retains the sign of the eigenvector which is useful in vector plots. This operation can be fairly time consuming for larger models, or models with a large number of modes.

1. To limit the output, use the filtering mechanism on the top of the form. Percentage of Max (abs) will limit that shown in the table to degrees-of-freedom that have Kinetic Energy greater than the Percentage Max Abs set on the slider bar. Or the user may simple select the Top n dof (abs) to keep, say, only the top 10 degrees-of-freedom with the highest Kinetic Energy in each mode. Again the slider bar sets the number of degrees-of-freedom to keep.

2. Select the load case of interest. Only loadcases which have KE results values will be displayed

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3. Select the subcases (modes) of interest. The “All” button will automatically select all subcases.

4. Press the Apply button to display the KE table. The KE table will appear in the large text box shown within the blue border to the right.

5. If the user desires to place the KE table in a report, it can be saved to an ASCII file using the Report button. Simply provide a file name in the file browser form that appears and press the OK button on that form. By default the file will have an extension of .rep. It is not necessary to include the extension when providing the name.

6. Finally, if the user feels that the degrees-of-freedom displayed in the KE table are representative, the user may create an ASET from them by pressing the Create ASET from list button. This will put the user into theAset Utilities (page. 59). The degrees-of-freedom from the KE table will have been automatically selected and an ASET name of aset_from_ke will be used for these.

Graphical visualization of Kinetic Energy percentage is perhaps a more useful tool for assessing measurement locations. This can be accomplished by using the Spike Plot (page. 57).


2.6 Group Energy TableThe purpose of this form is to provide convenient results assessing tools for Kinetic Energy (KE) and Element Strain Energy (ESE) quantities. Features of this application include the summation of KE for a group of nodes for one or more modes and the summation of ESE for a group of elements for one or more modes. The results are summarized by group and mode shape. They may be written to ASCII report files and matrix 3D bar chart plots are available for advanced visualization purposes. For KE, summation vectors are plotted at the group center of gravity.

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Kinetic EnergyThe Group Energy table for KE is very useful for determining modal contribution of detailed parts of the model such as a refined electronics box or a solar array. It is assumed that the user has a working knowledge of MSC.Patran groups.

1. Set the Type to Kinetic Energy which is the default.

2. Next select the Group Names of interest from the top list box. All groups are displayed in this list box. Press the All button if the user wants to quickly select every available group. If the user selects a group with elements that do not have mass properties assigned to them, then plotting a vector at the center of gravity will be impossible.

3. Select an appropriate load case from the Loadcase IDs list box. Only loadcases which have KE results values will be displayed

4. The mode shapes (Subcase IDs) associated to the selected load case are presented in the last list box. Select the modes of interest. Again the user can use the All button to quickly select all modes, or pick and choose modes of interest.

5. The user may selece how the Group Energy Report will be displayed. Choices include: display the table by Group Sort and then mode shape or by Mode Sort and then group or Both or None. If the user selects None, no report will appear and it will be impossible to create a 3D bar chart. Only summation vectors will appear if this plot is turned on in the next step.

6. If the user wishes to display a summation vector of KE at the center of gravity of each group, set the Plot pull down menu appropriately. Again, mass properties for all elements in each selected group must exist for this to be successful.


7. Press the Apply button to create the report and/or the vector plot of percentage total KE per group per mode.

Below are examples of a KE group report, 3D bar chart and summation vectors on various groups of a model. The vector plots can become cluttered if too many modes are selected at once. Pressing the Reset Graphics button will remove the vector plot from the graphics window. Pressing the Refresh Lists button will de-select all selections on the Group Energy Form.

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Once a report appears, the user may do two things from the report besides view it. Press the PLOT button to create a 3D bar chart showing the percentage total KE for each group per mode. To create an ASCII report file, press the Report button. The default extension is .rep which is not necessary to enter in the report name on the ensuing file browser form when creating the ASCII report file.

The following limitations are noted:

• Does not calculate rotational KE based on translational values.

• Uses absolute value when performing summation.

Vector plot of KE plotted at group CGs3D bar chart plot of total percentage

KE per group per mode


• Vector plot of summation is at the center of gravity for each group. This may be misleading for “long” parts such as the first mode of a cantilever beam.

Note: Be aware that the more groups and modes used, the slower will be the processing time. The vector plot can also spend significant time determining the groups center of gravity.

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Element Strain EnergyThe Group Energy table for ESE is very useful for determining highly strained locations for specific modes. This could be used in conjunction with determining where to update the model for specific modes (a “poor-mans” sensitivity). The percentage ESE is displayed.

1. Set the Type to Strain Energy.

2. Next select the Group Names of interest from the top list box. All groups are displayed in this list box. Press the All button to quickly select every available group.

3. Select an appropriate load case from the Loadcase IDs list box. Only loadcases which have ESE results values will be displayed. This form is not limited to data generated by MSC.ProCOR; any model with ESE results can be used.

4. The mode shapes (Subcase IDs) associated to the selected load case are presented in the last list box. Select the modes of interest. Again the user can use the All button to quickly select all modes.

5. The user may selece how the Group Energy Report will be displayed. Choices include: display the table by Group Sort and then mode shape or by Mode Sort and then group or Both or None. If the user selects None, no report will appear which is not very useful.

6. Press the Apply button to create the report

Once a report appears, the user may do two things from the report besides view it. Press the PLOT button to create a 3D bar chart showing the percentage total ESE for each group per mode. To create an ASCII report file, press the Report


button. The default extension is .rep which is not necessary to enter in the report name on the ensuing file browser form when creating the ASCII report file.

Note: Be aware that the more groups and modes used, the slower will be the processing time.

3D bar chart plot of total percentage ESE per group per mode

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2.7 MEM, Ortho, MACThe purpose of the MSC.ProCOR Matrix Results Form is to view the correlation related matrix results created in various MSC.Nastran runs.. This form is accessed from the MSC.ProCOR menus:

• Pretest GSET... | Pre-G MEM

• Pretest ASET... | Pre-A MEM, ORTHO, MAC

• Posttest ASET...| Post-A MEM, ORTHO, MAC

• Model To Model| Model-Model MEM, ORTHO, MAC

• or, MEM, ORTHO, MAC...

Read .op4 file: The file select menu will appear with a list of .op4 files. By default, the MSC.Nastran will create the following files:

• pre_grun.op4 -- created by Pretest GSET run

• pre_arun.op4 -- created by Pretest ASET run

• post_arun.op4 -- created by Posttest ASET run

• modelcomp.op4 -- created by ModelComp run

Displaying Matrices: After the file(s) are read, the listboxes are updated to show which matrices are available. The matrices are displayed by clicking on a name. These matrices are stored on the database for future use.

Note: The OUTPUT4 files must be in a specific format which is automatically taken care of by the DMAP. They are also stored in ASCII form for platform independence. Also note that the eigenvalue table for the GSET modes is taken from the GSET OUTPUT4 file.

Note: The data is stored on the MSC.Patran database for use in future sessions. If a subsequent run invalidates.

Note: The GSET matrices must be read in before the ASET matrices.


Filter: The filter is used to limit the output. All Modes will display the raw matrix with all the modes available. See Mode Filtering--Select Modes (page. 51) and Mode Filtering--Match Modes (page. 52) options described below.

Modal Effective Reactions: If the run requested that modal effective reactions be calculated, they will be stored in the PUNCH (.pch) file. Use the read button to read in the

Text Output Form: There are a total of 5 text output forms for which to display the formatted matrices. These will automatically be toggled for the user. If a user selects a matrix which is already displayed, that form will be brought to the front.

Mode Filtering--Select Modes

The Select Modes option causes an auxiliary form to be opened when a matrix is chosen for display. For MEM matrices, only one column will be selected. For ORTHO and MAC matrices, 2 columns will be displayed with the appropriate modes. The column headings will be set appropriately. For example, the form on the right has column headings “G” and “A” when “ORTHOGA” was selected. The user simply selects the modes of interest and presses the Show Filtered Matrix button to display a reduced matrix.

Note: The matrices are simply displayed by removing rows and/or columns from the original matrix; no additional computations are made.

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Mode Filtering--Match Modes

The Match Modes option causes an auxiliary form to be opened when a matrix is chosen for display. Since there are no “pairs” for MEM the Select Modes form will appear. For ORTHO and MAC matrices, a spreadsheet showing the mode matches, %Freq. Difference, Diagonal, and Max. Off-Diagonal for the Matrix.

To match modes manually, first select the mode in the spreadsheet to be changed and then select the mode in the listbox to change too. For instance, in the example shown here, Aset mode 5 was selected in the spreadsheet. The listbox automatically highlights mode 5. If a different ASET match for GSET mode 5 is desired, then it can be selected.


The autopair feature allows the user to set sliders for % Freq. Diff, Diagonal, and off-Diagonal terms. When the the Auto Pair button is selected, the spreadsheet will be updated to reflect the new pairs. These can be manually manipulated as above. To restore the “raw” matrix, press the Orig Pairs button.

The Get Stored MATNAME Pairs and the Store MATNAME Pairs buttons will get and store the current values in the spreadsheet on the database for subsequent use. MATNAME will be automatically set to the matrix name (in this example ORTHOGA) to remind the user which matrix is being matched.

Typical Output

Note: The Show Paired Matrix button will display the paired matrix in a text box and the Write Report button will write the current spreadsheet to an ASCII file.The matrices are simply displayed by removing rows and/or columns from the original matrix; no additional computations are made.

Modal Effective Mass Table

Orthogonality Table and 3D bar Chart

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The following matrices are generated for Test-Analysis correlation. See also How MSC.ProCOR Works (pg. 1-9).

Table 2-2 Correlation Matrices

Analysis Type / Matrix Name Description

Pre-Test GSET Analysis

MEMGGPCT MEM, Grun, Gmode, PerCenT

Pre-Test ASET Analysis

MEMAAPCT MEM, Arun, Amode, PerCenT

ORTHOGA

ORTHOGG

MACGA MAC Grows, Acols

Post-Test ASET Analysis

MEMTAPCT MEM, Trun, Amode, PerCenT

MEMTTPCT MEM, Trun, Tmode, PerCenT

ORTHOTA

ORTHOTT

ORTHOTG

MACTA MAC Trows, Acols

MACTT MAC Trows, Tcols

MACTG MAC Grows, Tcols

Model Comparison Analysis

MEM1PCT MEM, model 1, PerCenT

MEM2PCT MEM, model 2, PerCenT

ΦG

TMaa ΦA

ΦG

TMaa ΦG

ΦT

TMaa ΦA

ΦT

TMaa ΦT

ΦG

TMaa ΦT


Usage NotesTypical usage is as follows:

1. After a successful pretest GSET analysis, select MSC.ProCOR | Pretest Gset... | Pre-g MEM. Then select the Read .op4 file button. A file browser will appear allowing selection of the pretest GSET OUTPUT4 file. If default file names have been used this file is called pre_grun.op4.

When the GSET OUTPUT4 file has been successfully read, the user can display the Pre-G modal effective mass (MEMGGPCT) table and display a 3D bar chart or write an ASCII text report.

2. Read in the modal effective reaction punch file (if requested in analysis setup), the default file name being pre-g.pch. When this is done the user can display the modal effective reaction matrix.

3. Run the Pretest ASET analysis. Read the pre_arun.op4 file and display MEMAAPCT, ORTHOGA, ORTHOGG, and MACGA. Then display a 3D bar chart or write the formated table to a report file

4. Run the Posttest ASET analysis. Read the post_arun.op4 file and display MEMTAPCT, MEMTTPCT, ORTHOTA, ORTHOTG, ORTHOTT, MACGA, and MACGT. Display 3D bar charts or write the formated tables to report files as desired.

5. Display a 3D bar chart. Press the PLOT button on any of the matrix display forms. The 3D bar chart will appear along with the 3D Bar Chart form to allow the user to modify the chart characteristics (colors, labels, etc.). Press the Cancel Plot button on the form to put the 3D bar chart away.

ORTHO12

ORTHO21

MAC12 MAC 1rows, 2cols

Note: If the user does not cancel the 3D Bar Chart before closing a session, it will remain in the database. To remove it in a subsequent session, use the Clean up 3D Bar Chart pick from the main MSC.ProCOR menu.

Table 2-2 Correlation Matrices

Analysis Type / Matrix Name Description

Φ1

TM22 Φ2

Φ2

TM11 Φ1

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Note: The test MEM is an approximate modal effective mass calculated by substituting the test mode shapes for the analytical mode shapes. The analytical mass is used in the calculations.


2.8 Spike PlotThe purpose of this form is to allow for easy creation of vector result plots of correlation result quantities without having to go directly to the Results application. Usage of this form is fairly self-explanatory. Simply select the Loadcase ID, the appropriate Subcase ID (mode shape) and Vector Type. Then press the Plot Vectors button.

Vectors can be labeled, magnitudes changed, small terms filtered, colors altered and a variety of other displays manipulated. The user can display vectors on the current group or the entire model that is displayed in the current viewport. If the Keep Previous Plot toggle is on, then multiple result vectors can be plotted simultaneously with easy identification by changing the colors between each plot.

Vectors can be removed from the screen using the Reset Graphics button and if results appear out of phase, use the Flip Vector Direction button.

If no vector plot appears, change the Spike Plot Filter to 0.0 and try again. The default is 1.0.

Kinetic Energy vector results retain the sign of the eigenvector.

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When the Keep Previous Plot toggle is on, subsequent vector plot retain the scaling relative to the first plot.

A Typical Spike Plot


2.9 Aset UtilitiesThis utility allows for graphical selection and display of the ASET. The Actions include Add/Modify dof, Delete dof, Display Options, Verify, Write File, and Read File which are desribed below.

The Current ASET frame has a button which contains the name of the current ASET. Pressing this buttion will activate a subordinate form which allows the user to define and manipulate different ASETs. Also displayed are the total number of dof selected for the current ASET. This can be especially useful in pre-test analysis if there is a known limitation to the number of accelerometer the test lab can accommodate. The Current ASET is set automatically depending on how the user entered the ASET utility. The default name is Aset_Nodes. If the ASET was generated from kinetic energy, the label would be different.

ASET Name OptionsBefore creating an ASET definition the user must create an new ASET name and select it to be the current ASET name. This is done from this form which is invoked from the ASET Name Options form by pressing the The button in the Current ASET frame.button. There are four Actions on this form:

Create - simply type in a new name in the Create ASET name databox. On Apply the ASET name will be created and it will be set as the Current ASET name.

Set Current - pick the ASET name from the list box that is to become current. By default the user does not have to press the Apply button unless the Auto Apply on Select toggle is turned OFF. Once the ASET name is set to be current, the user may add degrees of freedom to this ASET. An ASET name must be current in order to affect changes to it.

Delete - select the ASET name to delete from the list box and then press the Apply button.

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Add Nodes to Cur. Group - the nodes from the Current Aset name will be added to the MSC.Patran database current group when the Apply button is pressed.

Add/Modify dofThe Degrees of Freedom (dof) which are to be added are chosen by clicking “on” the appropriate dof label. Every time a node or group of nodes is selected, they will appear in the Select Node data box near the bottom of the form. If the Auto Execute toggle is set ON, the indicated degrees of freedom will be added to the ASET automatically. If it is OFF, the user will have to press the Apply button to add them to the ASET. The user may change the Degrees of Freedom for each selection as often as desired.

Depending on the Display Options (page. 62), the graphics window will automatically update the ASET markers for quick visual identification

.

Note: If a node is already in the ASET, and it is selected again, it will be overwritten with the new dof definition.

Note: The ASET degrees of freedom are graphically displayed in the “displacement” coordinate system of the node. This is referred to as the “analysis” coordinate frame in MSC.Patran. That is, the coordinate from in which the analysis will calculate the displacements of the node and not the coordinate from in which the node location was defined.

Note: If a dof is in the MSET or SSET, a warning will be issued and it will not be placed in the ASET. See Verify (page. 63) for further definition.


Delete dofThe Delete dof action looks very similar to the Add/Modify dof action. However, the dof frame is disabled and all the dof toggles are off. The result of selecting a node in this scenario will remove all ASET dof from that node. If the desire is to remove a single dof, then use the Add/Modify dof action.

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Display Options

1. Display Marker Options frame

The Group optionmenu has options of All Nodes, Current Group, or Posted Groups. This is used to filter the nodes on which display arrows are drawn.

If the Auto Display Update toggle is on, then any changes to the ASET will automatically be registered. It is recommended to leave this on in most cases.

The Clear Display on Cancel button will erase the ASET arrows when the form is cancelled.

2. Display Arrow Options

The user can change the color or size of the translation and rotation dof display arrows

3. Node Labels

The options here are

If “ext” ids are used then a map between the internal and external ids must be defined. An “XXX” will appear for any external id which is not defined. See UFF Utilities (page. 69) and/or BDF Match Utility (page. 82) for mapping examples.

4. Clear Display Markers erases the current ASET arrows from the graphics window.


VerifyThe Check MPC Conflicts toggle will automatically check for set conflicts between the ASET and the MSET. The MSET is the dependent dof set in MSC.Nastran. This includes dependent dof defined on MPC, RBE2, RBE3, etc. entries.

The Check SPC Conflicts toggle will automatically check for set conflicts between the ASET and the SSET. The SSET is the constrained dof set in MSC.Nastran. These are SPC sets in MSC.Nastran and displacement Loads/BCs in MSC.Patran. The Use BC’s from Loadcase: listbox will select the loadcase from which the displacement LBC’s are used when checking for SSET conflicts

Note: Only loadcases with LBCs will be available to choose from in the listbox. The active loadcase will be automatically selected by default. Changing the loadcase in the listbox will automatically update the active loadcase.

Note: When using Add/Modify dof, the set conflicts will be automatically checked based on the values in this form. Warnings will be displayed in the history window for any nodes with invalid dof during the add/modify operation

Note: If model changes are made, such as deleting a Node, adding an MPC, or adding/modifying a displacement boundary condition, the Apply button must be pressed to check the ASET for any conflicts. Failure to recheck the model may cause fatal errors in the MSC.Nastran analysis.Warnings are displayed for any degrees of freedom which have become invalid. Offending degrees of freedom will be removed from the ASET definition.

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Write File / Read FileThe Write File and Read File actions have the same options. Use the Define ASET File button to select the file to read/write, then press the Apply button to execute the action.

It is not required to write the ASET definition to a file. ASET degrees of freedom are retained in the MSC.Patran database for use in subsequent sessions. There can be several different ASET names for different sets of ASET degrees of freedom.

Note: When reading from a file, acceptable formats of ASET entries are ASET and ASET1 in fixed or free field format with multiple continuation cards that immediately follow the parent card. Replication cards (i.e., =, *1, ==) are unacceptable formats.


2.10 Animate SpecialThis utility provides a way of animating two deflected shapes simultaneously in either a single viewport superimposed or in two side by side viewports.

Usage of this special animation form is primarily for PLOTELs (plot elements) that connect the ASET degrees of freedom to provide a definition of the actual model. It is not recommended for larger models (> 5000 elements) or for use with fringe plots. Performance is machine dependent.

It is very useful in comparing mode shapes from different sources (e.g., model 1 versus model 2 or test versus model).

Use with multiple viewports requires that the user first create the viewports using the standard MSC.Patran viewport utilities under Viewport | Create, Post, and Tile.

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In all cases the user must create two groups which must be posted, one to each viewport for two viewport animation, or both to the same viewport. The two groups can be exact copies of one another, containing the same exact entities. In most cases, these groups should contain PLOTELs which simply outline the model when using the reduced ASET mode shapes.

Once this is all set, the animation setup is simple. The form is setup side by side for selection of the two modes to animate:

1. Select the Viewport in which the first mode shape will be animated and the viewport in which the second mode shape will be animated. For animation in a single viewport, select the same viewport for both.

2. Select the Loadcase in which the first mode shape is contained and, likewise, the Loadcase of the second mode shape. For example, to animate the first mode of the pretest GSET model against the first mode of the pretest ASET model, select pre-g as the first load case and pre-a as the second load case.

3. Select the mode of interest (Subcase) for each of the two selected load cases. In this example the first mode shape is selected from each.

4. Make sure that the correct Result is selected for each. In this case, they are both set to Eigenvectors, Translational.


5. Press the APPLY button. The special animation control form will appear. Animation will not actually take place until the user presses the START button on this form. Or, press the Step button for viewing a single step at a time.

The animation will continue until the STOP button is pressed.

The user may alter the speed of the animation and change the scale factor which is the deformation scale relative to the model size. The default is set to 10% of the maximum model dimension.

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2.11 Re-phase ResultsThis is a simple utility to create new results where the original results are 180 degrees out of phase. This form quickly creates a new result type which is -1.0 times the original. This is useful when comparing modes which were normalized differently.

The feature works on Eigenvectors, Constraint Forces, Kinetic Energy (KE), and Drive Point Residues (DPRs). A new result type will be created with a “(-)” designation. For example:

(-)Eigenvectors, Translational(-)Eigenvectors, Rotational

To re-phase results:

1. Select a Loadcase ID (Results Case).

2. Select a Subcase ID (mode shape).

3. Select the Vector Type (result quantity).

4. Press the Create Phased Result (*-1) button.

5. Go to the Results application and select the Result Case and Subcase of interest. It should now show new an new result quantity with the “(-)” qualifier in front of it.

Note: The rephased results are stored in Coord 0

Note: After creating the new results, the user may have to reselect the Results Case in the Results application to register the new results.


2.12 UFF UtilitiesSeveral Universal file utilities are included to translate and provide compatibility between a test universal file and the current MSC.Patran model. These utilities translate both model and test results data and are accessed from the UFF Utilities on the main MSC.ProCOR menu.

Geometry MatchFour translation actions are allowed from this form.

Read Coordinate Systems

When reading a Universal file, this operation must be done first. An exception would be if it is known that the coordinate systems in the universal file are the same as the coordinate systems in the MSC.Patran database. Having the proper coordinate systems is required to ensure that coordinate definitions are available in the database before reading in the nodes and translating the test data. Appropriate warning messages are issued for duplicate coordinate systems. Only the option of selecting a Universal File (UFF File INPUT) is activated when reading in coordinate systems on the formt. The step are to:

1. Set the Translation option to Read Coord. Systems.

2. Press the UFF File INPUT button and select the Universal file using the file browser.

3. Press the Apply button.

Read Nodes

When this option is activated various widgets on the form become activated and visible. The user must have read coordinate systems from the Universal file before attempting to read the nodes (or the user must otherwise ensure coordinate system

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compatability). When the nodes are read in from the Universal file, they can be displayed as geometric points, actual nodes, or markers only. Markers are not stored in the database.

A tolerance can be set (default = 0.01) for warning the user if there is not a good match between a node in the Universal file and that of the actual model in the database. Also a map between the Universal file nodes and the “closest” in the actual database can be created by storing this information in an external file.

Steps to read nodes are:

1. Read coordinate systems from the Universal file first.

2. Set the Translation option to Read Nodes.

3. Press the UFF File INPUT button and select the Universal file using the file browser if necessary. This most likely was done already when reading the coordinate systems and is not necessary to do again if the information resides in the same Universal file.

4. If the user wants or needs to create a map between the Universal file nodes and the nodes in the MSC.Patran database, turn ON the Create Node Map toggle. Additional comments on node mapping follow these steps.

5.Under Node Translate Options, select how to store and/or display the Universal file nodes. The options are to Plot Markers only, Generate Nodes, or Generate Geometric Points.

6.Press the Apply button.

When mapping nodes, only the closest node is reported when generating the map. If multiple nodes are coincident, or equidistant from an existing node in the database, only one node is returned. If the Find All Equid. Matches toggle is ON, then MSC.ProCOR will choose the first node returned and issue a message to the effect that other possibilities exist. Also the mapping can be done for All Model Nodes or only those in the Current Group. Note that using the current group can greatly reduce the processing time; but be careful that all nodes in the UFF file will be matched with nodes in the current group to get an accurate map.


External to Internal Node Map

If a node map was generated, the External to Internal Node Map form will appear:

The node map will be stored on the database for future use. The default name when matching Universal file geometry is UFF Translate Node Map. The map may be modified by selecting a spreadsheet value and entering the new PATRAN node number to map the external node number to. Actions include

1. Store New Map: Stores the values presently displayed in the spreadsheet

2. Set Current: Allows the user to select which map to use in mapping operations.

3. Delete Map: Removes a map from the database (cannot delete current map).

4. Read Map From File: writes current map to an external file.

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5. Write Map to File: reads map from an external file

Read Trace Lines

When this option is activated various widgets on the form become activated and are updated. The user must have read nodes from the Universal file before attempting to read the trace lines. When the trace lines are read in from the Universal file, they can be displayed as curves connecting geometric points, or plot elements (PLOTELs) connecting nodes. This depends on how the nodes were read from the Universal file.

If the nodes have not been read into the actual database, but a mapping file exists between the Universal file nodes and those in the database, the user can specify the node map. The trace lines will then be created connecting the nodes in the database according to the node map.

Steps to read trace lines are:

1. Read nodes or create node map from the Universal file first.

2. Set the Translation option to Read Trace Lines.

3. Press the UFF File INPUT button and select the Universal file using the file browser if necessary. This most likely was done already when reading the nodes or creating the node map and is not necessary to do again if the information resides in the same Universal file.

4. If the Use Node Map toggle is ON, the tracelines will be created by connecting them between the database nodes represented in the node map. The current map will be displayed in the frame. If a different map is desired, select the map by pressing the Select Node Map button.

Note: The map file format is free-format using space(s) as the delimeter. The first line of the file is the character string “Ext/Int Model Map”; the second line is the number of map pairs; subsequent lines have the format:external_id(integer) space(s) internal_id(integer). Do not use commas anywhere in the file.


5. Under Traceline Translate Options, select how the tracelines will be displayed and stored in the database. The options are Curves on Points, or Plotels on Nodes. The will depend on how the Universal file nodes were imported.


Read Aset Dof

When this option is activated various widgets on the form become activated and are updated. This option reads Universal file data sets 755 (degree of freedom sets) or 1802 (coordinate trace) and prompts the user whether or not to add this information to the current ASET. Usage is as follows:

1. Set the Translation option to Read Aset Dof.

2. Press the UFF File INPUT button and select the Universal file using the file browser if necessary. This most likely was done already when reading the nodes or creating the node map and is not necessary to do again if the information resides in the same Universal file.

3. If the Use Node Map toggle is ON, the appropriate node mapping will be used between the database nodes and those in the Universal file.


This is a convenient way of automatically generating an ASET from the Universal file data. The ASET degrees of freedom are visually presented as done in the ASET Utilities form. The standard SPC and MPC checks are also performed with warning messages presented when problems are encountered. An ASET name of “UFF_coord_trace_derived.”

Usage Notes

For most scenarios when the UFF coordinate systems match those of MSC.Patran:

1. Read the coordinate systems from the Universal file.

2. Read the nodes from the Universal file. Select Create Node Map and Plot Markers Only.

3. Read tracelines from the Universal file. Select Use Node Map and Create Plotels on Nodes.

Note: No checks between the UFF displacement coordinate systems and the MSC.Patran displacement (analysis) coordinate systems are done. They are assumed to be congruent.

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4. Read ASET. Select Use Node Map.

For other situations where the UFF coordinate systems do not match those of MSC.Patran:

1. Read the coordinate systems from the Universal file.

2. Read the nodes from the Universal file. Select Create Geometric Points.

3. Read tracelines from the Universal file. Select Create Curves on Points.

4. Manipulate the MSC.Patran model to align it with nodes from the Universal file.

5. Re-read the nodes from the Universal file. Select Create Node Map and Plot Markers Only.

6. Read tracelines from the Universal file. Select Use Node Map and Create Plotels on Nodes.

7. Read ASET. Select Use Node Map.

Translate Test DataThe purpose of this form or utility is to convert externally supplied test eigenvectors to MSC.Nastran DMIG format and the frequencies to MSC.Nastran DMI format. This conversion is done by creating an external MSC.Nastran bdf files that are later included in the post test ASET MSC.Nastran analysis as described in Post-Test ASET Analysis Setup (page. 31). This is a necessary step to be done before the post test ASET run can be performed at which time the correlation matrices are computed and test modes shapes can be imported into the MSC.Patran database (see OUTPUT2 Read Special (page. 36)) for display and comparison purposes.

Two test data file types are supported.


Universal File to DMIG

For test modes shapes and frequencies that exist in a Universal file, follow these steps to set up the translation:

1. Set the Translation Type to UFF to DMIG.

2. Select the Universal file using the UFF File INPUT button. A file browser will appear to allow for file selection.

3. Specify a new punch file which to be created by pressing the DMIG (.pch) File OUTPUT button. Again this done through a file browser form. This file will contain the translated eigenvectors from the Universal file in DMIG format. This file will be used as an include file in the subsequent post test ASET analysis run. It is suggested that the default .pch extension be used to avoid confusion.

4. Specify a new file to contain the test frequencies in DMI format by pressing the Frequency File OUTPUT button. This is also done via a file browser with a default extension of .dmi. This file will contain the test frequencies in DMI format which will be specified as an include file for the subsequent post test ASET analysis run.

5. Press the Apply button. The .pch and .dmi files, for later use in the post test ASET analysis run, will be automatically created.

This is the recommended method to use for test data translation for a number of reasons, but mainly because the ASET map is not required and the frequency information is contained in the file.

At times it may be necessary to re-specify coordinate directions because they are different from test to the MSC.Patran model. The displacement coordinate system between the test file and the database model is assumed congruent. If not, press the Coord Sys. Transformation button. From the form that appears the user can specify the MSC.Patran degree of freedom coordinate system relative to that defined from the test. For example, if the test +X direction is, in reality, the MSC.Patran -Y direction, then set UFF X to -Y in the form below and do similarly for the other two degrees of freedom.

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Also the user can map the Universal file nodes to that of the model nodes if there is a mismatch by turning on the Remap Grids toggle and specifying the mapping file. This file must have been created using Read Nodes (page. 69) and creating a mapping file. It may be more appropriate to use the map generated by the Universal file utilities rather than the one deduced by the form to the left.

Note:There is no check on the validity of the map. It is possible to specify a left-hand system.

OUTPUT4 File to DMIG

For test modes shapes that exist in as ASCII formatted OUTPUT4 file, follow these steps to set up the translation:

1. Set the Translation Type to Output4 File to DMIG.

2. Select the OUTPUT4 file using the OP4 File INPUT button. A file browser will appear to allow for file selection.

3. Specify a new MSC.Nastran input file name which will be created using the NASTRAN Bulk File OUTPUT button. Again this done through a file browser form.

4. Select the Aset Name that applies to the test mode shapes. This ASET must have created already.

5. Press the Apply button. A MSC.Nastran input file by the name specified in an earlier step will be created. The user must run this input file through MSC.Nastran (a manual operation). This will create a punch file of DMIG images used later in the post test ASET analysis run.

The recommended method to use for test data translation is the Universal file. The OUTPUT4 file translation is generally used when the SDRC IDEAS software is used to convert a Universal file containing test data to an


OUTPUT4 file. The format of the OUTPUT4 file is a specific format containing the ASET eigenvectors in matrix form (ascending degrees of freedom versus eigenvector). Therefore the OUTPUT4 file is assumed to be in ascending node order with an exact map to the current ASET. No provisions are made for mapping different node labels.

Note that the test frequencies are not present in the OUTPUT4 file. To specify the frequencies corresponding to the test mode shapes from the OUTPUT4 file the user must use the Manual Freq Input option described below. If the user does not specify the frequencies, the post test ASET analysis will simply label the modes in ascending unit frequencies, i.e., mode 1 = 1.0 Hz, mode 2 = 2.0 Hz, etc.

Manual Frequency Input

To manual specify the frequencies corresponding to the test mode shapes, use this utility. This is necessary when translating test data from OUTPUT4 files. If this is not done, the post test ASET analysis run will assume frequencies are the same as the mode number, i.e, mode 1 = 1.0 Hz., mode 2 = 2.0 Hz., etc.

From the main Translation Setup form, select Manual Freq Input. The form will update and a single button will appear called Test Freq. Definition. Press this button to get the form shown:

This form is a simple spreadsheet input. Click on the cell next to the Mode # number of interest. Enter the frequency in the Mode # Frequency data box on the top of the form to enter the frequency. The user must press the Return or Enter key to affect any change to the spreadsheet.

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To add rows or delete rows, activate the cell to delete or add. Then press the Insert Row or Delete Row buttons. When adding a row, the row will be placed above the selected cell. If there are blank cells between cells that have data or zero frequency cells, then press the Pack & Sort Rows button to compress and remove those rows.

To save the data in a .dmi file as an MSC.Nastran include file of DMI cards, press the Define File button to specify a file name. The default extension of .dmi is used. Then press the Write File button. If the user wishes to read frequencies from a file to fill the spreadsheet and make modifications, press the Read File button. Do not forget to re-save any changed data to the file.


2.13 Generate Reduced ModelThe purpose of this form is to generate a reduced model (mode shapes and mass matrix or mass and stiffness matrices) for use in model to model correlation which only operates on the residual structure. There is a simple and an advanced display of this form. The simple mode dims some of the options such that they are not selectable.

Usage of this form will automatically set up an MSC.Nastran job called gen_maapha which is representative of the reduced model corresponding to the selected ASET degrees of freedom, if any are selected. In many ways, it performs very similarly to the Analysis Setup forms for creating the pre-g, pre-a, and post-a analysis runs for model to test correlation.

Reduction Type: “Simple” or “Advanced”. “Simple” options are: Reduction Method = None; Matrix Output = Pha, Maa (modes,mass); Model Output Formate = Output4 (.op4). See further discussion below.

DB/Param/Otuput Options...: this opens the form to set job parameters (number of modes, PARAM GRDPNT, etc.) See MSC.Nastran DB/PARAM/OUTPUT Options (page. 33) for full details.

Reduction Method: “None” or “Guyan”. “None” means that there will be no Guyan reduction; “Guyan” means that there will be Guyan reduction based on the Aset Name selected.The ASET is defined using the Aset Utilities (page. 59).

Matrix Output: “Pha, Maa (modes,mass)” or “Maa, Kaa (mass, stiffness).” This specifies which type of matrix to be output. Modes, mass is recommended for most applications using MSC.ProCOR. If transferring a model to another organization, then mass/stiffness may be a better choice.

Matrix Output Format: “Output4 (.op4),” “DMIG (.pch/.dmig),” or “Both.” This specifies the format of the output matrices. The ASCII OP4 toggle can be set to output4 the matrices in ASCII instead of binary. The DMIG option is recommended if the model to be correlated with has mismatched nodes. This file will be referenced later during the Model Comparison Setup (page. 88).

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Mode shape (Pha) output and the reduced mass (Maa) and/or stiffness (Kaa) matrices can be written to

When the Apply button is pressed, the user is placed into the Analysis application, ready to submit the newly created gen_maapha job. The Analysis Preference must be set to MSC.Nastran for this to work properly. The gen_maapha job is automatically configured with the following:


All defaults retained.

2. Solution Type...

Solution type is set to Normal Modes (SOL 103). No solution parameters are modified.


A new .dmi file is assigned in the FMS section. DMAP alters are placed in EXEC deck. No CASE control is modified. Various parameter cards are placed in BULK data section for matrix formatting.


A new subcase called gen_maapha is associated with the gen_maapha job.

All of this information can be viewed from the Analysis application if necessary. The created job is “run-ready,” meaning the user may press the Apply button on the Analysis application form without having to modify or add any additional information. It is suggested that the user review the information before submitting the job. If the job name already exists the user will be prompted for overwrite permission.

Note: On Apply, if the Restart from Database toggle is ON, a “read-only” restart MSC.Nastran input file will be created. The user can submit the job as an Existing Deck. This operation assumes that the MSC.Nastran database has been saved previously.


Usage Notes

The Simple option on this form is intended for simple model changes of the same model. Examples could be: Fail-Safe analysis (i.e. removing an MPC or element), material property changes (i.e. changing one set of material properties from steel to aluminium), or a physical property change (i.e. changing the thickness or cross section of some members). Other possibilities exist.

The Advanced option on this form is intended to compare models with significant differences, or models which have different nodes. Examples could be: Models from 2 different groups (i.e. stress model vs. dynamics model), models with 2 different configurations (i.e. with and without lumped mass, or model with solar arrays deployed vs a model with the solar arrays stowed, etc.), or proposed configuration changes (i.e. “what if” we add an avionics box, or move it from locatation “a” to location “b”), etc. The recommended use is to generate “dmig” entries for the model so that a map can be used to match up this model with the comparison model. Creating the map is described in BDF Match Utility (page. 82)

In either Simple or Advanced, a frequency file named lama22.dmi will be created. This file will be used in Model Comparison Setup (page. 88).

Note: When using the Simple option, the nodes between the 2 models being compared must not change: they must have the same number of nodes and the same node order. If this restriction cannot be maintained, then the Advanced option must be used.

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2.14 BDF Match UtilityThe functionality of this utility is similar to that of the UFF Utilities (page. 69) for mapping test model information to the model in the MSC.Patran database. In this case the same thing is done with MSC.Nastran bulk data and the model in the MSC.Patran database to set up model to model correlations.

There are five major activities that must take place to map a model from an MSC.Nastran input file to set up the subsequent model to model correlation:

Read Coordinate Systems

This operation ensures that coordinate definitions are available in the database before reading in the nodes from the bulk data so that coordinate systems match between the two models. If the coordinate systems are identical between the two models with the same IDs, there is no need to perform this step.

The step are to:

1. Set the Translation Type to Read Coord. Systems.

2. Press the BDF File INPUT button and select the file that contains the bulk data using the file browser.


Note: If coordinate systems have duplicate IDs, they must be coincident. There is no error checking for this.


:Read Nodes

When this option is activated various widgets on the form become activated and visible. The user may need to read coordinate systems from the bulk data before attempting to read the nodes if the necessary coordinate definitions do not exist in the database. When the nodes are read from the bulk data, they can be displayed as geometric points, actual nodes, or markers only. Markers are not stored in the database.

A tolerance can be set (default = 0.01) for warning the user if there is not a good match between a node in the bulk data and that of the actual model in the database. Also a map between the bulk data nodes and the “closest” in the actual database can be created by storing this information in an external file.

Steps to read nodes are:

1. Read coordinate systems from the bulk data first if necessary.

2. Set the Translation Type to Read Nodes.

3. Press the BDF File INPUT button and select the file containing the bulk data using the file browser if necessary. This most likely was done already when reading the coordinate systems and is not necessary to do again if the information resides in the same file.

4. If the user wants or needs to create a map between the nodes in the bulk data and the nodes in the MSC.Patran database, turn ON the Create Node Map toggle. This will require that the user specify a file to store the information by pressing the Map File... button. Additional comments on node mapping follow these steps.

5. Set the Geometry Search to either Current Group Nodes or All Model Nodes. Searching the current group can greatly reduce the processing time, especially for large models.

6. Under Node Translate Options, select how to store and/or display the nodes from the bulk data. The options are to Generate Geometric Points, Generate Nodes, or Plot Markers only.

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When mapping nodes, only the closest node is reported when generating the map. If multiple nodes are coincident, or equidistant from an existing node in the database, only one node is returned. In review, the mapping function performs the following:

• Checks for compatibility of displacement coordinate systems. Rectangular coordinate systems must have the same coordinate system transformation matrix (CSTM). For cylindrical and spherical systems, the origin must be the same as well as the CSTM.

• Prints warnings for bulk data nodes which cannot be matched to a database node within the specified tolerance.

• Reports all equidistant nodes from the bulk data to the database nodes, if this option has been turned on.

• Searches all nodes in the MSC.Patran database for matches or only those in the current group.

• Generates a map called “BDF Translate Node Map.” To modify the map see External to Internal Node Map (page. 71)

• Maps only ASET nodes that appear in the bulk data, if this option is turned on. This will create a new ASET name called bdf_translated_aset.


.

Read Plotels

When this option is activated the form is activated and updated. You should read nodes from the bulk data before attempting to read the plot elements. When the plot elements, which are essentially tracelines, are read in from the bulk data, they can be displayed as curves connecting geometric points, or plot elements (PLOTELs) connecting nodes. This depends on how you read in the nodes from the bulk data.

If the nodes have not been read into the actual database, but a mapping file exists between the bulk data nodes and those in the database, you can specify the mapping file. The PLOTELs will then be created connecting the nodes in the database according to the mapping file.

Steps to read PLOTELs are:

1. Read nodes or create node map from the bulk data first if necessary.

2. Set the Translation Type to Read Plotels.

3. Select BDF File INPUT and select the file containing the bulk data. This was probably done when reading the nodes or creating the node map and is not necessary if the information resides in the same file.

4. If the Use Node Map toggle is ON, the tracelines will be created by connecting them between the database nodes represented in the mapping file. The current map will be displayed. If a different map is desired, select the map by pressing the Select Node Map button.

5. Under Traceline Translate Options, select how the tracelines will be displayed and stored in the database. The options are Plotels on Nodes, or Curves on Points. This will depend on how the bulk data nodes were imported. (If Use Node Map is on, then the curves will be created using the model nodes from the map).

Note: All bulk data formats are supported although replication cards are not expanded, i.e., =, *1., ==; =3, etc. Continuation entries must immediately follow the parent. No warning messages are issued.

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Re-map DMIG

This uses the mapping array to renumber nodes on DMIG entries in the external bulk data so that correlation can be performed with the internal MSC.Patran database model. Congruent coordinate systems between both models is assumed.

1. Set the Translation Type to Remap DMIG then select the DMIG file using the DMIG File (.pch) button. A file browser will appear to allow for file selection.

2. Turn ON the Use Node Map toggle and select the Map File... if necessary, which must have been created earlier when reading the nodes from the bulk data.

3. Press the Apply button. A new DMIG file will be created called remapped_dmig.pch which will be selected later during the model Model Comparison Setup (page. 88)

Create Frequency DMI

This creates DMI cards so that frequencies can be properly labeled in the correlation run. This requires that an OUTPUT4 file containing a LAMA matrix.

1. Set the Translation Type to Create Freq. DMI, select the frequency file using the Freq. File (.op4) button. A file browser will appear to allow for file selection.

Note: A group will be created named BDF_Plotels which has the plotel elements and nodes.

Note: This feature was required by previous versions of MSC.ProCOR, but is no longer required. However, it has been retained in this version and may be removed in future versions.


2. Press the Apply button. This creates a file containing the frequency information that can be selected later in the Model Comparison Setup (page. 88).

Usage Notes

It is recommended to use the bulk data from the file gen_maapha.bdf, generated by the gen_maapha job. See Generate Reduced Model (page. 79). The recommended process is to read coordinate systems, nodes, PLOTELs and DMIG in that order.

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2.15 Model Comparison SetupThis utility will fill in all the forms in the Analysis application appropriately for any of the model comparison types supported. Without this form, the setup for each run would be tedious to the point of frustration. It also eliminates the need to edit the MSC.Nastran bulk data after it is written. In other words, a run-ready input file is created.

Any of the following model comparison combinations are supported:

• Internal vs. External op4 - Internal MSC.Patran database model (converted to a MSC.Nastran input file) versus an External model in the form of matrices stored in an OUTPUT4 file.

• Internal vs. External dmig - Internal MSC.Patran database model (converted to a MSC.Nastran input file) versus an External model in the form of matrices stored in DMIG format.

• External op4 vs. External op4 - Both models exist as matrix information stored in OUTPUT4 files.


• External op4 vs. External dmig - One model exists as matrix information stored in OUTPUT4 form while the other is stored in matrix form in DMIG format.

DB/Param/Otuput Options...: this opens the form to set job parameters (number of modes, PARAM GRDPNT, etc.) See MSC.Nastran DB/PARAM/OUTPUT Options (page. 33) for full details.

The form has two modes, Simple and Advanced. In simple form, model comparison setup is done for the internal database model versus an external DMIG model only. Typical usage of this form is a follows:

1. Set the Type to Advanced or Simple.

2. Select the Model 1 and Mode 2 Options based on which model comparison combination is desired.

3. For Model 1 Internal models, the user may specify a Reduction Method, if necessary. Select the Aset Name to be used for Guyan (ASET) reduction this option is used.

4. For Model 1 and 2 External op4 models, the user must select the OUTPUT4 file that contains the matrix (M, K, Phi) information using the Model 1/2 Shape File button. Also, if available, the user can select the frequency definition (DMI) file using the Model 1/2 Freq. File button. If none is selected then Mode1=1Hz, Mode2=2Hz, etc. Model 1 can be reduced by selecting setting the Reduction Method to Guyan (ASET) and selecting an ASET. If the OUTPUT4 file contains M and K, the Recompute modes must be ON. The resulting INPUTT4 file can also be saved in ASCII form if the ASCII INPUTT4 toggle is ON.

5. For Model 1 and 2 External dmig models, the user must select the DMIG punch file (.pch) that contains the matrix (M, K, Phi) information using the Model 1/2 Shape File button. Also, if available, the user can select the frequency definition (DMI) file using the Model 1/2 Freq. File button. If none is selected then Mode1=1Hz, Mode2=2Hz, etc. Model 1 can be reduced by selecting setting the Reduction Method to Guyan (ASET) and selecting an ASET. If the DMIG punch file contains M and K, the Recompute modes toggle must be ON. The resulting INPUTT4 file can also be saved in ASCII form if the ASCII INPUTT4 toggle is ON.


Note: The OUTPUT4 file and/or DMIG model can contain mass (M) and stiffness (K) matrices from which the mode shapes are recomputed, or it can contain M and Phi, the mode shapes, in which case the modes are not recomputed. These matrix files of reduced models are created in Generate Reduced Model (page. 79).

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The user is then placed in the Analysis application and a new job called Model_Comp has been created. It is run-ready and the user should be able to press the Apply button in the Analysis application to have the job submitted automatically. The Analysis Preference must be set to MSC.Nastran for this to work properly. The Model_Comp job is automatically configured with the following:


All defaults retained.

2. Solution Type...

Solution type is set to Normal Modes (SOL 103). No solution parameters are modified.


OUTPUT2 and OUTPUT4 files are assigned in the FMS section. DMAP alters are placed in EXEC deck. Certain parameters are set in the CASE control. And DTI (direct table input) cards are placed in BULK data section for proper handshaking between MSC.Nastran and MSC.ProCOR.


A subcase called modlcomp is created which uses the default load case.


The Model_Comp job is associated to the default subcase

All of this information can be viewed from the Analysis application if necessary. The created job is “run-ready,” meaning the user may press the Apply button on the Analysis application form without having to modify or add any additional information. It is suggested that the user review the information before submitting the job. If the job name already exists the user will be prompted for overwrite permission.

The following limitations exist:

DMIG matrix names must be KAAEXT1, MAAEXT1, PHAEXT1 for model 1 and KAAEXT2, MAAEXT2, PHAEXT2 for model 2.

Note: On Apply, if the Restart from Database toggle is ON, a “read-only” restart MSC.Nastran input file will be created. The user can submit the job as an Existing Deck. This operation assumes that the MSC.Nastran database has been saved previously.


OUTPUT4 files must have the following matrix order: Mass (M) matrix followed by stiffness (K) matrix when modes are to be recomputed, or eigenvectors (Phi) followed by mass (M) matrix when using existing mode shapes.

The preferred method for external models is the DMIG form.

The OUTPUT4 file must be in ascending grid order of the ASET grids. It is up to the user to ensure compatibility between model numbering schemes. By default, supported versions of MSC.Nastran do not reorder grids.

DMIG files are not checked for overdefined or underdefined mass/stiffness/mode shape terms. Check the mapping file spreadsheets from the BDF Match Utility (page. 82) carefully. Make sure all ASET degrees of freedom are mapped.

93CHAPTER 3Examples


3 Examples

� Example 1 - GSET Model

� Example 2 - GSET Model Results

� Example 3 - ASET Selection and Model Setup

� Example 4 - Views and Group Setup

� Example 5 - ASET Model Results

� Example 6 - Translate Test Data

� Example 7 - Test/Analysis Correlation

� Example 8 - Model Updates

� Example 9 - Model-Model Comparison - Take 1

� Example 10 - Model-Model Comparison - Take 2

� Example 11 - Universal File Translation

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The following examples are provided to help you get familiarized with MSC.ProCOR:

The first eight examples, dealing with an antenna model, must be run through in sequential order since they build on each other.

Example 1 - GSET Model (page. 95) - Run an analysis on the full size model (GSET) with the intention of subsequent test/analysis correlation.

Example 2 - GSET Model Results (page. 106) - Review results of the full size model (GSET) with the intention of subsequent test/analysis correlation.

Example 3 - ASET Selection and Model Setup (page. 128) - Select candidate accelerometer locations and run an analysis on the reduced model (ASET) with the intention of subsequent test/analysis correlation.

Example 4 - Views and Group Setup (page. 140) - Create groups and viewports for later use in visualizing result quantities.

Example 5 - ASET Model Results (page. 145) - Compare the GSET model to the ASET model to determine sufficient measurement locations in the reduced model, representative of the full model.

Example 6 - Translate Test Data (page. 161) - Take measured test data and convert it to DMIG and DMI formats for subsequent use in the test/analysis correlation run.

Example 7 - Test/Analysis Correlation (page. 164) - Run the test/analysis correlation to compare the math model against actual test measurements and investigate the results.

Example 8 - Model Updates (page. 173) - Update the model to get better correlation with test.

The next two examples, dealing with model-to-model comparisons, should be completed together and it is suggested that the user familiarize himself with the first seven examples before attempting these.

Example 9 - Model-Model Comparison - Take 1 (page. 178) - A course meshed model is compared to a fine meshed model in a like manner to test/analysis correlation.

Example 10 - Model-Model Comparison - Take 2 (page. 200) - Simple model changes are investigated in a like manner to test/analysis correlation.

Example 11 - Universal File Translation (page. 212) - An actual modal test/analysis problem with real test data from a Universal file.

95CHAPTER 3Examples

3.1 Example 1 - GSET ModelThe objective of this first exercise is to build a “routine” FE model which would be suitable for dynamic analysis and then submit a GSET run so that dominant modes, potential accelerometer locations, and potential excitation points can be determined. The GSET run is one in which no special stiffness or mass reductions occur (other than reducing dependent or SPC degrees of freedoms). The GSET model will be built with the expectation of doing test/analysis correlation and for helping in giving insight into possible test setup scenarios. The GSET model will be run through MSC.Nastran to this end.

To get started, create a new, empty working directory. Next, copy the following file from the directory indicated below from your MSC.ProCOR installation into the new directory:

<install_dir>/procor_files/examples/modelbuild.ses

From the new directory, invoke MSC.Patran. A screen similar to this should appear:

It is assumed that MSC.ProCOR has been properly installed and tested and that you know how to get MSC.Patran up and running. It is also assumed you have a good working knowledge of the basic MSC.Patran functionality. Therefore, no in-depth detailed descriptions of actual MSC.Patran usage are given in these exercises.

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Build the Model

1. After the graphical interface starts, open a new database from File | New and call it “antenna.” It is suggested that you change the template database on this form to the mscnastran_template.db. Press the OK button to create the empty database. Keep the Analysis Preference set to MSC.Nastran if asked.

97CHAPTER 3Examples

2. Play the provided session file to create the model under File | Session | Play... Select the session file modelbuild.ses. Press the Apply button.

The session file creates a cantilevered shell model that is fixed on one end as shown here.

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Enable MSC.ProCORSelect the MSC.ProCOR from the Tools menu. The MSC.ProCor main menu will appear.

Set Up the GSET RunSet the Pretest GSET toggle and slect the Analysis Setup from the MSC.ProCOR main menu.

3. Set up the ensuing form as shown:

99CHAPTER 3Examples

1. Run Type

Make sure this is set to Pretest GSET.

2. DB/Param/Output Options

See the form in Set GSET DB/PARAM/Output Options (page. 100)below.

3. Mode Shape Output

For the purposes of this exercise, mode shape output will be saved in OUTPUT4 formatted files.

4. Modeshape File Select

The default mode shape file is set to pre-g.phg. It is suggested that you leave this as the default. You may specify another name if you wish by pressing the Modeshape File Select button. Note that the label changes to Select OP4 File. The file specified here will be created when the job is submitted. The mode shapes stored in this file from the GSET run are used for orthogonality and MAC checks with the ASET model.

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Set GSET DB/PARAM/Output OptionsSet up the parameters as follows:

1. Database Output Options -- use defaults

2. Restart From Database -- not used here

3. Lanczos Extraction -- the defaults as shown are used in this example

4. Run Method -- UseFull Run if your system is set up to run MSC.Nastran from within an MSC.Patran session. Otherwise use Analysis Deck.

5. bdf Echo -- use None.

6. bdf Format -- use small field.

7. PARAM,AUTOSPC -- use YES.

8. Mass Calc. -- use Lumped.

9. PARAM,WTMASS -- use 1.0.

10. PARAM, GRDPNT -- used 999 (see also Calculate Center of Gravity (page. 104))

101CHAPTER 3Examples

11. KE % Filter -- the default of 1.e-008 is appropriate.

12. Calc. Mode Eff. Rxn -- click this option ON (by default it is not selected.

13. Use BC’s from Loadcase: select the Default loadcase as the one containing lbc’s for this job.

Press the Apply button to activate the DB/PARAM/OUTPUT OPTIONS Then press Apply on the Analysis Setup form. The Analysis Setup form will disappear from the screen and will be replaced by MSC.Patran’s standard Analysis application form. A modal form will also appear informing you of the following:

Jobname ‘pre-g’ was created. It was associated to Subcase ‘pre-g’ which uses the pre-g Loadcase (=Default Loadcase). USER ACTION: Select ‘pre-g’ in [Available Jobs] AND check the ‘pre-g’ under [Subcase Create...] for accuracy.

At this point a new analysis job has been created called pre-g. You have no control over the name of the analysis job. Pre-test GSET models are always named pre-g. If you are ever working with more than one GSET model at the same time, you will have to put them in separate directories.

The new analysis has been configured with the appropriate FMS, Executive, Case Control, and Bulk Data items via the Direct Text Input data boxes on the Analysis application.

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Inspect the GSET Analysis SetupOn the Analysis application, select the pre-g job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.


All defaults are left on this form except for the Numbering Options... where subcase numbers (Load Cases) are offset, which is required.

2. Solution Type...

The Solution Type is set to Normal Modes.


Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. OUTPUT2 and OUTPUT4 files assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. Various parameters are set in the Case Control for controlling the DMAP. And finally direct table input (DTI) cards are put in the Bulk Data for proper handshaking between MSC.Nastran and MSC.ProCOR.


The subcase, pre-g, is created and associated to the pre-g load case. Output Requests... have been set as SPC forces, element strain energy (ESE), and eigenvector data. The pre-g subcase is created by copying the default subcase with the default boundary conditions. SPC forces must be calculated for the Kinetic Energy (KE) and Drive Point Residue (DPR) information to be valid.


The pre-g subcase is selected for the analysis job.


Submit the GSET AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.

If MSC.Nastran is not configured on the same machine that you are running this exercise, or you do not have direct submit access to some MSC.Nastran executable, then set the Action | Object | Method to Analyze | Entire Model | Analysis Deck. This will create the input deck without submitting the job. You can then take the file, called pre-g.bdf, to the appropriate machine and run the job. If you do this, don’t forget to bring back all the output result files.

Whether you submit the job as a Full Run or Analysis Deck, you will be asked for overwrite permission. Answer YES. After running the MSC.Nastran job, the following files of importance will be created:

• pre-g.bdf - the MSC.Nastran analysis input deck.

• pre-grun.op4 - an OUTPUT4 formatted file containing modal effective mass and frequency information used when displaying the effective mass and making 3D bar charts.

• pre-g.op2 - an OUTPUT2 file containing standard output read by MSC.Patran such as mode shapes, SPC forces, and element strain energy (ESE).

• pre-g.phg - an OUTPUT4 formatted file containing mode shape information for use in cross-orthogonality checks with the ASET model during the ASET analysis.

• pregdpr.op2 - an OUTPUT2 file containing drive point residue (DPR) information to be read back into the database.

• pregke.op2 - an OUTPUT2 file containing kinetic energy (KE) information to be read back into the database.

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Calculate Center of Gravity

From the main MSC.Patran Tools menu, select Mass Properties...

Press the Define Region button and select the whole model by using the group called default_group. Press the Apply button to display the mass properties.

Note: For this example, the session file created Node 999 at the CG for you. This section is included as a supplement for users not familiar with using the mass properties calculator in MSC.Patran.


The purpose of calculating the center of gravity is to subsequently create a node at that point to reference for the Grid Point Weight Generator in MSC.Nastran (PARAM,WTMASS,node ID). So take note of the coordinate locations of the center of gravity [2.415, 35.37, 0.0].

The next step would be to create this node. YOU DO NOT NEED TO DO THIS. The session file already created it for you, but for completeness, these are the steps you would take if you needed to created this node:

1. Select the Finite Elements application from the application switch on the main MSC.Patran form.

2. Change the Action | Object | Method to Create | Node | Edit.

3. Change the Node ID List to 999 to create Node 999 - or some very large number relative to the highest node number in your model.

4. Turn OFF the Associate with Geometry toggle.

5. Type in the Node Location List the coordinates of the node, e.g., [2.415, 35.37, 0.0] - all real values.


Now on the Analysis application, you need to specify this node for the Grid Point Weight Generator. THIS IS MANDATORY.

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3.2 Example 2 - GSET Model ResultsThe objective of this exercise is to evaluate the results from the GSET model to determine dominate modes, candidate accelerometer locations, and candidate excitation locations so that decisions can be made about model reduction and test setup. This typically includes visual inspection of mode shape deformed plots, modal effective mass and reaction evaluation, kinetic energy (KE), group energy, element strain energy (ESE) and drive point residue (DPR) displays.

Since this exercise builds on that of the first example, remain in the current working directory with all the files produced from that example. Open the database (if not open already) called antenna.db.

Read ResultsUnder the MSC.ProCOR menu, select Pretest GSET | OP2 Read Special. The form at the right will be displayed. It should be pre-selected with the Pre_G .op2 file. If not, select it then press the Apply button. This action reads and processes three files created by the GSET analysis run.

• pre-g.op2 - mode shapes, element strain energy

• pregdpr.op2 - drive point residue results

• pregke.op2 - kinetic energy results


Display Mode Shapes

Open the MSC.Patran Results application by selecting it from the application switch on the main MSC.Patran form.

1. Set the Action | Object to Create | Deformation.

2. Select the first mode, pre-g, Mode 1:Freq.=5.9374.

3. Select Eigenvectors, Translational.

4. Press Apply.

5. Repeat this for as many modes as you would like to view. Take note of the mode types, such as first major bending, axial, torsion, etc., second major bending, axial, torsion, etc..

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.


Display Modal Effective Mass (MEM)Now display the MEM for the pre-test GSET model:

1. Select Pretest GSET | Pre-G MEM from the main MSC.ProCOR menu to display the form to the right.

2. The first order of business is to read in the MEM data from the OUTPUT4 file produced by the pre-test GSET analysis. Press the Read .op4 file button. A file browser will appear from which you should select the pre_grun.op4 file and press the OK button.

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3. The data is now available and you can display the MEM by pressing the DISPLAY G-set MEM button. A form with the report will appear.

4. If you wish to have a text file containing this report, press the Report button, supply a file name with no extension in the file browser that appears and press the OK button. A file with the extension .rep will be created in the specified directory in the file browser.

5. Create a 3D bar chart of the MEM information. Press the PLOT button. A three dimensional bar chart will be created displaying the percent MEM for each mode in each of the global coordinate directions. You should see a plot similar to that shown below.


6. Experiment with the 3D Bar Chart form that accompanies the plot to change its display. These plots can also be rotated, panned, and zoomed like any normal MSC.Patran graphics display.

7. Press the Cancel Plot button when you are done viewing the plot.

Note: There may be operations, such as quitting from MSC.Patran or closing a database, that do not clean up the3D bar chart. Use the Clean up 3D Bar Chart selection on the main MSC.ProCOR menu if necessary to remove a bar chart.

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Interpreting MEM

The MEM is an effective way to identify modes with high mass participation in the model. These are considered dominant modes and are often identified as “target” modes during a modal test. For a complex structure with many modes, the identification of target modes can reduce the data collection and reduction performed by the lab and reduce the correlation task.

For example, in the above MEM plot we can see that Mode 1 and 8 are dominant modes in that they displace the most amount of mass relative to the other modes. The direction in which they are displaced also gives us clues as to the type of modes they are, without visually seeing deformation plots. Mode 1 is a dominant bending mode in the x rotation direction and Mode 8 is the dominant bending about the z axis. Visual plots of the mode shapes confirm this from the previous step. It is important that these modes (and some of the others) be retained in the reduced ASET model in a subsequent exercise to ensure proper representation. Note that some mass directions are not excited below 35 Hz. Let us assume for the rest of these examples, that modes over 35 Hz are not important to target. This could be because the forcing function frequencies above 35 Hz contain a small fraction of the total forcing energy.

Display Modal Effective Reactions (MEFFRXN)Now display the MEFFRXN for the GSET modes:

1. On the same Matrix Results form, press the Read Meffrxn .pch file button. This file was also created from the pre-test GSET analysis if modal effective reactions were requested, which they were in the previous exercise. From the file browser, select the file pre-g.pch and press the OK button.


2. The Display Meffrxn button becomes active. Press this button to display the MEFFRXN report.

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3. As you did with the MEM report, make a 3D bar chart by pressing the PLOT button.

4. Play with the settings on the 3D Bar Chart form until you have the plot display as you like. Press the Cancel Plot button when you are done viewing.

Interpreting MEFFRXN

The MEFFRXN is an effective way to identify modes which have high contributions to the interface forces. Like the MEM, modes with high MEFFRXN are considered dominant modes and will be identified as target modes during the modal test. For a structure which has a redundant set of reactions, MEFFRXN can often identify dominant modes missed by MEM.

The above bar chart shows the percentage of modal effective reaction on all constrained degrees of freedom for all modes. For example, note Mode 8 has the most reaction forces in the x and y directions which is consistent with a force-couple reaction of bending about the Z axis. Mode 1 is dominate in the z translational and rx/ry rotational directions, indicative of a major bending mode.


Report Kinetic Energy (KE)To get a tabular listing of the KE for each degree of freedom for each mode, choose the KE Table pick from the Pretest GSET... menu selection.

When this form appears:

1. Select the Loadcase ID called Pre-G-KE (this should be the only one available.)

2. Select the desired subcases (in this case use the “All” button).

3. Press the Apply button. The table will appear in the text box.

4. Press the Report button if you would like the report saved in a file. Supply a name in the file browser with no extension. Press the OK button and the file will be written with a .rep extension.

To filter the table such that only those degrees of freedom above a certain percentage of the absolute maximum are shown or, say, the degrees of freedom with the top 10 KE values are displayed, use the Automatic Filtering on the top of the form and press the Apply button to effect the change. Experiment with this as you see fit.

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To visualize KE better, rather than sift through a table, use the post-processing tools described next.

Press Cancel to close the KE Table form.

Interpreting KE

The magnitude of the KE of each mode for any particular degree of freedom indicates the locations that should be kept in the reduced ASET model and the locations that should be instrumented in the actual test (accelerometer placement). It also helps indicate excitation locations (shakers). Degrees of freedom with large amounts of KE are worthy candidates for accelerometer and/or shaker placement. Sometimes, when a refined model is used, it is better to look at the contribution of a group of nodes. The Group Energy exercise which will follow shows how to do this.


Spike Plots of Eigenvectors, KE, and DPRSelect Pretest GSET... | Spike Plot from the main MSC.ProCOR menu. The Spike Plot form appears. This is a simplified version of the Results application for creating vector plots.

1. Select the Loadcase ID called Pre-G-KE.

2. Select Mode 1 as shown to the right.

3. The Vector Type should be Kinetic Energy, which is the only choice in this case.

4. Press the Plot Vectors button. The plot will appear similar to that shown below.

5. Experiment with the display of the plot by changing the Vector Magnitude Scale, the Spike Plot Filter, the colors of the arrows, the labels, and other display features on this form as you see fit.

6. In particular, turn ON the Keep Previous Plot toggle and change the arrow colors between plots. Select different modes to plot each time.

7. Display a deformed shape (in the Results application) and then make a spike plot of KE.

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8. Press the Reset Graphics button before closing this form. If you forget to do this, the vectors will remain until you re-open the form and do this. If the vectors are displayed when the MSC.Patran session is terminated, then the vectors will automatically be deleted and need to be recreated, if desired, in a subsequent session.

9. This form may also be used for other vector quantities, such as eigenvectors or DPR.

Interpretation of Spike Plots

Spike plots provide a quick, but limited, results interface for displaying vector results. Many of the same features of this form can be performed using the Results form on the MSC.Patran main menu. The advantage of this form is speed. It is easy to “flip” the vector directions and overlay different results; for instance, the mode shapes from the model overlaid with the mode shapes from test.

Display and Report Group Kinetic Energy (KE)The first exercise created a number of groups (collections of FE entities such as nodes and elements) when the session file was played. The main beam and the left and right fingers of the model were placed in groups. The purpose of this is to view which groups contain higher percentages of KE for specific modes. First, generate a summary table of KE by group and mode:

1. Select Pretest Gset... | Group Energy from the main MSC.ProCOR menu.


2. On the Group Energy form that appears, set the Type to Kinetic Energy.

3. Choose all groups by pressing the All button next to Group Names. Deselect the default_group by holding down the Ctrl key and clicking on it with the mouse such that all groups are selected but the default_group.

4. Select the load case Pre-G-KE (only loadcases with KE will be selectable).

5. Select all modes by pressing the All button next to Subcase IDs.

6. Set Report to Both and Plot to None.

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7. Press the Apply button to see an organized report of KE by mode and by group.


8. Press the PLOT button on the summary table form to get a graphic view of the KE by group and mode. Close the plot down by pressing the Cancel Plot button on the 3D Bar Chart form when you are done viewing.

Now plot the KE vectors for each group at the center of gravity.

1. On the Group Energy form, keep all the selections as before except choose only Mode 1 and Mode 2.

2. Change the Report to None and the Plot to Vector @ CG, then press the Apply button again.

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Interpreting Results

The advantages of viewing these results are very powerful. If the analyst looks at the raw KE percentages, he may miss an important accelerometer location. This can occur because of mesh refinement: the more refined the mesh, the lower the KE for any individual degree of freedom. For instance, in a coarse model, a large electronics box may be modeled with a concentrated mass and the KE contributions would be apparent. But for a model where the electronics box is modeled in detail with quad elements, the mass at each node would be small, and the overall KE contribution could be missed. By putting components into logical groups, the KE contribution of a component becomes clear.


Report Group Element Strain Energy (ESE)Now generate a report of ESE by group and mode:

1. Select Pretest Gset... | Group Energy from the main MSC.ProCOR menu, if the form is not already visible.

2. On the Group Energy form that appears, set the Type to Strain Energy.

3. Choose all groups by pressing the All button next to Group Names. Deselect the default_group by holding down the Ctrl key and clicking on it with the mouse such that all groups are selected but the default_group.

4. Select the load case pre-g (only loadcases with element strain energy will be selectable).

5. Select all modes by pressing the All button next to Subcase IDs.

6. Set Report to Both.

7. Press the Apply button to see an organized report of ESE by mode and by group.

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8. Press the PLOT button on the summary table form to get a graphic view of the KE by group and mode. Close the plot down by pressing the Cancel Plot button on the 3D Bar Chart form when you are done viewing.

Interpreting Results

In the case of element strain energy, the results indicate portions of the structure which are doing the most work in a mode. For instance, in the case of an airplane wing it is helpful to know which spars or ribs are being exercised (or worked) in a particular mode. This insight becomes even more powerful when the test modes do not match the analysis modes. Knowing the parts of a structure with high ESE for a mode pinpoints the areas where a change in stiffness will affect the mode the most. This can also be used as a “poor mans” sensitivity. In addition, the analyst can determine before hand how many modes will be affected by a local stiffness change.

Another powerful feature of Group Energy, is that the groups can be added or modified while reviewing the results. A new analysis does not have to be performed.


Calculate Drive Point Residues (DPR)Now calculate DPRs for the first seven GSET modes. The main purpose of looking at DPRs is to determine where to apply load input to the structure in order to excite the modes of interest. In this case we are concerning ourselves with modes 1 through 7 only.

1. Under the main MSC.ProCOR menu, select Pretest GSET... | DPR Calc to bring up the form to the right.

2. Pick the Pre-G-DPR load case from the Loadcase IDs list box (only loadcases with DPR will be selectable).

3. A new derived result name must be supplied. Enter DPR_G_1_7 in the DPR Derived Results Name data box.


This will create a new Result Case with a number of result quantities the most interesting of which is the weighted average DPR. To view these results, go to the Results application.

1. In the Results application, set the Action | Object to Create | Fringe.

2. Select DPR_G_1_7, Weighted Average as the Result Case to be viewed.

3. The Fringe Result should be automatically selected as Drive Point Residue, Translational.

4. Ensure that the Quantity is set to Magnitude and press the Apply button.

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This will display a fringe plot of the weighted average DPR for modes 1 through 7. Also display a vector plot on top of the fringe plot. This can be done as a spike plot from the MSC.ProCOR menu or as a marker plot from the Results application.

1. Open the Spike Plot form from the MSC.ProCOR menu under Pretest GSET...

2. Find and select the DPR_G_1_7 load case ID.

3. Find and select the Weighted Average DPR.

4. Turn the All Nodes toggle ON.

5. Press the Apply button to create the vector plot.

or

1. In the Results application, set the Action | Object | Method to Create | Marker | Vector.

2. Select the DPR_G_1_7 Result Case.

3. Select the Weighted Average DPR as the Vector Result.

4. Press the Apply button. (Set the Display Attributes to Screen Scaled vector definitions to get a plot similar to that above.)


Interpreting DPR

The DPR results are very powerful if used correctly. For instance, in this example, we chose modes 1-7. A review of the MEM and mode shapes indicates that all of these modes have some motion in the out-of-plane (z) direction. Mode 8, however, is a bending mode in the xy plane. If we had included mode 8 in the calculations, the weighted average for the resultant DPR would have been zero and there wouldn’t have been much use. But, since modes 1-7 were used, we can find a single location which should excite all of these modes. Mode 8 should be excited in the x-direction farthest from the reaction points. Knowing this about the structural behavior may lead to a single shaker at a skewed angle (in the xz plane) at the location indicated by the plots above.

For a more complicated structure, with no clear planes of symmetry, several DPRs may be calculated by grouping different modes. For instance, a structure with 10 modes of interest may have 3 “ideal” shaker locations: shaker location 1 may get modes 1,4,5 and 10; shaker location 2 may excite modes 3 and 8; and shaker location 3 may excite the remaining modes. There is no set “rule” for these, although reviewing and understanding the MEM and mode shape plots can provide a lot of insight into the modes which should be grouped when calculating DPR. The most important consideration is to avoid “bad” shake locations.If a target mode is not excited well, then testing may be delayed while a new shaker location is determined and the test hardware is modified.

Experiment with the Results application and the spike plots to display useful quantities. The trick is to choose locations with high DPR values (to excite all modes of interest) as excitation locations.

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3.3 Example 3 - ASET Selection and Model SetupThe purpose of this exercise is to select an ASET and generate a “traceline” of the ASET points. After reviewing the data from the GSET analysis run, you have decided on choosing all intersecting points and exterior corners for a trial ASET. This will provide a reasonable “traceline” of the model and should provide a reasonable representation of the full model.

ASET SelectionThe general concept of selecting and/or creating an ASET is accomplished by selecting a current ASET name. This name may need to be created, but once it is created, it must be set the current ASET. All operations (selections of degrees of freedom) on the ASET Create form become part of the current ASET.

1. From the MSC.ProCOR menu, select Pretest ASET... | Aset Utilities.

2. Select a current ASET name. The default is Aset_Nodes and it is suggested that you accept the default.

3. Select the nodes described above and as shown in the plot below. This is a graphical operation done by pointing and selecting with the mouse. Note that the label in the Current ASET frame updates each time a node or selection of nodes is picked, indicating the current number of degrees of freedom selected. The Auto Execute toggle is ON, making this a very interactive procedure. Graphically you will see vectors on each node representing the degrees of freedom selected. The three translation Degrees of Freedom are selected as the default.

Practice selecting and deselecting as you see fit or until you have selected the indicated nodes.

Note: To remove an inadvertent selection, set the action to Delete dof and reselect the node.

Note: The Apply button never needs to be pressed when Auto Execute is ON.


If a node which has SPC or dependent MPC degrees of freedom associated with it is selected, then a message similar to this will be displayed, warning of this conflict. Check the history window also for more message information. The conflicting degrees of freedom will not be added to the ASET.

The ASET is stored in the database under Aset_Nodes, which is created automatically during the selection process. This is not the same thing as a MSC.Patran group, but is more like defining a Load/BC.

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Create the TracelineFor visualization purposes, it is necessary to connect the dots. That is, we must take the ASET nodes and place lines between them to properly visualize the reduced model.

1. From the main MSC.Patran menu, open the Group application from Group | Create.

2. In the New Group Name data box, enter the new group name called trace.

3. Keep the Make Current toggle ON.

4. Press the Apply button to create the group.

The new trace group will be empty of any entities. Now add the ASET nodes to the new group.

1. Back on the ASET Create form (Pretest ASET... | Aset Utilities), in the Current ASET frame press the Aset_Nodes button.


2. On the form that comes up, change the Action to Add Nodes to Cur. Group.


All the nodes from the currently selected ASET, Aset_Nodes, are added to the trace group. To complete this mini-exercise, we need to add two more nodes to the group such that a proper traceline can be created.

1. Back on the Group form, set the Action to Modify, or select Group | Modify from the main Group menu.

2. The Target Group should be set to trace. If not, set it to trace using the Change Target Group... button.

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3. In the Member List to Add/Remove data box, enter Node 1 3 or select them from the graphics screen using the cursor.

4. Press the Add button. Make sure you get both Nodes 1 and 3 added to the group.

5. Change the Action to Post (or select Group | Post) and post only the trace group to the screen.

6. To better see the nodes from this group change the node size to 9 point by pressing the icon on the top level MSC.Patran form:

This will result in a plot of nodes. Now you must connect the dots to visualize the ASET model by creating bar elements between the nodes and assigning plot element properties to them.

1. Open the Finite Element application from the main MSC.Patran application switch.

2. Set the Action | Object | Method to Create | Element | Edit.

3. Set the first element in the Element ID List to be 1001. This is not required, but is good practice.

4. Set the Shape to Bar.

5. Set the Topology to Bar2.

6. Set the Pattern to PWL for piece-wise linear.


7. Not connect the dots. Graphically select the first node, say Node 1 or Node 3 at the bottom of the page. This will fill the select data box on the form. Use the Shift key to select the rest of the nodes in the order in which you would like them connected. In the end you should end up with the following posted after pressing the Apply button.

I

The final step is to create plot elements (PLOTELs).

Note: If you make a mistake, press the Undo icon and try again. In unix, the undo button lools like an eraser, in windows, it looks like other undo icons.

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1. Open the Element Properties application from the main MSC.Patran application switch.

2. Set the Action | Object | Type to Create | 1D | PLOTEL.

3. Use traceline as the new Property Set Name.

4. Select all the bar elements from the graphics viewport. Or simply type in Element 1001:1044, assuming these are the element numbers.

5. Press the Add button to add these elements to the Application Region.

6. Press the Input Properties... button to expose the following form:

7. Simply set the only property value that appears here to DUMMY by using the adjacent pull down menu. Then press the OK button.


These new PLOTEL elements will be used and written to the ASET analysis input file when submitting the MSC.Nastran job in the next step.

Note: When selecting the bar elements, make sure that you have the select data type icon set to beam element:


Set Up the ASET RunSelect Analysis Setup from the Pretest ASET menu on the main MSC.ProCOR menu.

Set up the resultant form as shown:

1. Run Type

Make sure this is set to Pretest ASET.

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2. DB/Param/Output Options...

The defaults on this form are based on the last job; in this case the pre-g job. The defaults should be fine.

3. Reduction Method:

This should be set to Guyan (ASET).

4. Aset Names


The Aset_Nodes ASET should be automatically selected for you. This is a required input to the pre-test ASET analysis and will be used to create the ASET cards in the input file.

5. G-Mode Input

The default mode shape file is set to pre-g.phg. This is the mode shape file created from the pre-test GSET run which is necessary for calculating cross-orthogonality. The default should be set to pre-g.phg and no action is required.

Press the Apply button. The Analysis Setup form will disappear from the screen and will be replaced by MSC.Patran’s standard Analysis application form. A modal form will also appear informing you of the following:

Jobname ‘pre-a’ was created. It was associated to Subcase ‘pre-a’ which uses the pre-a Loadcase (=Default Loadcase). USER ACTION: Select ‘pre-a’ in [Available Jobs] AND check the ‘pre-a’ under [Subcase Create...] for accuracy.

At this point a new analysis job has been created called pre-a. You have no control over the name of the analysis job. Pre-test ASET models are always named pre-a. If you are ever working with more than one ASET model at the same time, you will have to put them in separate directories.


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Inspect the ASET Analysis SetupOn the Analysis application, select the pre-a job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. OUTPUT2 and OUTPUT4 files assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. Various parameters are set in the Case Control for controlling the DMAP. And finally direct table input (DTI) cards are put in the Bulk Data for proper handshaking between MSC.Nastran and MSC.ProCOR plus the ASET cards.


The subcase, pre-a, is created and associated to the pre-a load case. Output Requests... have been set as SPC forces, element strain energy (ESE), and eigenvector data. The pre-a subcase is created by copying the default subcase with the default boundary conditions. SPC forces must be calculated for the Kinetic Energy (KE) and Drive Point Residue (DPR) information to be valid.


The pre-a subcase is selected for the analysis job.


Submit the ASET AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.

If MSC.Nastran is not configured on the same machine that you are running this exercise, or you do not have direct submit access to some MSC.Nastran executable, then set the Action | Object | Method to Analyze | Entire Model | Analysis Deck. This will create the input deck without submitting the job. You can then take the file, called pre-a.bdf, to the appropriate machine and run the job. If you do this, don’t forget to bring back all the output result files.

When you submit the job, Full Run or Analysis Deck, you will be asked for overwrite permission. The following files of importance will be created by the analysis:

• pre-a.bdf - the MSC.Nastran analysis input deck.

• pre-arun.op4 - an OUTPUT4 formatted file containing modal effective mass and frequency information used when displaying the effective mass and making 3D bar charts.

• pre-a.op2 - an OUTPUT2 file containing standard output read by MSC.Patran such as the ASET mode shapes, SPC forces, and element strain energy (ESE).

• preadpr.op2 - an OUTPUT2 file containing drive point residue (DPR) information to be read back into the database.

• preake.op2 - an OUTPUT2 file containing kinetic energy (KE) information to be read back into the database.

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3.4 Example 4 - Views and Group SetupThe purpose of this exercise is to set up multiple graphics windows and groups for use in side-by-side comparisons. MSC.ProCOR does not modify or enhance the current capabilities of MSC.Patran for the purposes of this exercise. However, the casual user may not be aware of some of these capabilities, or how to implement them. For this purpose, this exercise is included here.

Create Multiple ViewportsCreate three new viewports using Viewport | Create from the main MSC.Patran menus. This is a simple operation:

1. Viewport | Create

2. New Viewport Name

Enter aset_view.

3. Apply

Repeat this two more times using the names gset_view and test_view. Now post the gset_view and aset_view viewports to the screen.

1. Viewport | Post

2. Select aset_view and gset_view using the Cntl key to select the discontinuous selection in the list box.

3. Apply

4. Viewport | Tile. This will automatically position the two viewports side by side.

You can re-size, move, or position the windows as you desire. Cancel the forms when you are done.


Create Groups for Results PostingNow create three groups.

1. Group | Create

2. New Group Name

Enter aset_trace.

3. Apply

This operation creates an empty group called aset_trace. Repeat this for the other two groups called gset_trace and test_trace.

Next, add entities to these groups. The same entities will be added to all three: the tracelines or plot elements (PLOTELs).

1. Group | Move/Copy

2. Select trace in the From Group list box.

3. Select aset_trace in the To Group list box.

4. Apply

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Repeat this operation two more times by placing the entities from group trace into groups gset_trace and test_trace.

Now post the aset_trace group in the aset_view viewport and the gset_trace group in the gset_view viewport.

1. Group | Post

2. Select Groups to Post

Select only the aset_trace group.

3. Before you press the Apply button, make sure that the viewport called aset_view is the current or active viewport. In unix, this is accomplished by clicking the mouse with the cursor over the outer border of the viewport. A red border indicates the active graphics window. In Windows, simply click anywhere in the desired viewport to make it active.


4. Press Apply

Repeat this operation for the gset_trace group in the gset_view viewport. Do not forget to make the gset_view viewport active before posting the group to it.

Click in outer boundary of viewport to make active. The cursor will change to a hand, indicating the outer border.

Active Viewport indicated by red border.

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Color SelectionNow change the group colors for easy identification. The GSET traceline will be colored green and the ASET traceline will be colored yellow as in the display above.

1. Under the Display menu, select Entity Color/Label/Render...

2. Change the mode to Group.

3. Select the target group. Do the gset_trace first.

4. Set the Render Style to Wireframe.

5. Set the Shade Color to some shade of green that you like.

6. Apply

For the purposes of this exercise, repeat this operation for the other groups as follows:

• gset_trace: green

• aset_trace: yellow

• test_trace: blue

When you are done, you should see something similar to the two plots above.

Before moving on to the next exercise, post the trace group to the default_viewport viewport.

1. First use Viewport | Post.

2. Then use Group | Post.


3.5 Example 5 - ASET Model ResultsThe purpose of this exercise is to compare the GSET model to the ASET model. This will help determine if sufficient accelerometer or measurement locations (ASET degrees of freedom) have been selected for the reduced model, to best represent the full model.

Read ResultsUnder the MSC.ProCOR menu, select Pretest ASET | OP2 Read Special. The form at the right will be displayed. It should be pre-selected with the Pre_A .op2 file. If not, select it then press the Apply button. This action reads and processes three files created by the ASET analysis run.

• pre-a.op2 - mode shapes and element strain energy

• preadpr.op2 - drive point residue results

• preake.op2 - kinetic energy results

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Display Mode Shapes

Open the MSC.Patran Results application by selecting it from the application switch on the main MSC.Patran form.

1. Set the Action | Object to Create | Deformation. select the first mode, PRE-G, Mode 1:Freq.=5.9374, then select Eigenvectors, Translational.


2. Under Display Attributes, change the Deformed color to green and the Render Style to Free Edge.

3. Under Plot Options, Save Deformation Plot As: Gmode_1.

4. Press Apply. This will plot the first GSET mode shape into the viewport. The object now, is to plot the equivalent ASET mode shape on top of the GSET mode for comparison purposes.

1. Go back to the Select Results mode of the Results application form.

2. Select the first mode of the ASET, pre-a, Mode 1:Freq.=5.9444.

3. Select Eigenvectors, Translational.

4. Under Display Attributes, change the Deformed color to yellow and the Render Style to Free Edge.

5. Under Plot Options, Save Deformation Plot As: Amode_1 then press Apply.

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You should get a plot similar to that below. Note that the two modes are almost coincident.

Note: If the modes are out of phase, use Rephase Results under the Pretest ASET... selection. Select the mode you want to re-phase (multiply by -1) and press the Create Phased Result (*-1) button. Cancel the form and reselect the mode in the Results application. You may have to toggle the Results application OFF and ON again before the new results appears, i.e., (-)Eigenvector.


Repeat this for as many modes as you would like to view for comparison purposes. Sometimes it is better to compare mode shapes via an animation. This is covered at the end of this exercise.

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Display Modal Effective Mass (MEM)Now display the MEM for the pre-test ASET model:

1. Select Pretest ASET... | Pre-A MEM, ORTHO, MAC from the main MSC.ProCOR menu to display the form to the right.

2. The first order of business is to read in the MEM data from the OUTPUT4 file produced by the pre-test GSET analysis. You may have already done this from a previous exercise, but if you have quit from MSC.Patran since then, you will have to do it again. Press the Read G-set .op4 file button. Nothing else on the form will be selectable until this operation is completed. A file browser will appear from which you should select the pre_grun.op4 file and press the OK button.

3. Now read the MEM data from the OUTPUT4 file produced by the pre-test ASET analysis. Press the Read A-set.op4 file button and select the file pre-arun.op4. All operations on the form with respect to Correlation Matrices should be available now.


4. The data is now available and you can display the MEM by selecting MEMAPCT. A form with the report will appear.

5. If you wish to have a text file containing this report, press the Report button, supply a file name with no extension in the file browser that appears and press the OK button. A file with the extension .rep will be created in the specified directory in the file browser.

6. Create a 3D bar chart of the MEM information. Press the PLOT button. A three dimensional bar chart will be created displaying the percent MEM for each mode in each of the global coordinate directions. You should see a plot similar to that shown below.

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7. Experiment with the 3D Bar Chart form that accompanies the plot to change its display. These plots can also be rotated, panned, and zoomed like any normal MSC.Patran graphics display.

8. Press the Cancel Plot button when you are done viewing the plot.

Interpreting MEM

See the comments on the GSET Interpreting MEM (page. 112). A comparison of this ASET plot to that of the GSET shows that the major modes of interest are being captured from the reduced model.

Note: There may be operations, such as quitting from MSC.Patran or closing a database, that do not clean up the3D bar chart. Use the Clean up 3D Bar Chart selection on the main MSC.ProCOR menu if necessary to remove a bar chart.


Display Orthogonality/MAC Results (ORTHO/MAC)Now display the orthogonality for the GSET vs. the GSET and the cross-orthogonality for the GSET vs. the ASET modes:

1. On the Pretest Results form, press the Display ORTHOGG button. This will report the pre- and post- matrix multiplication of the GSET modes with respect to the ASET reduced mass matrix.

2. As you did with the MEM report, make a 3D bar chart by pressing the PLOT button.

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3. Play with the settings on the 3D Bar Chart form until you have the plot display as you like. Press the Cancel Plot button when you are done viewing.


4. Close the report down by pressing the Cancel button and then Display ORTHOGA matrix in a similar fashion as was done for the ORTHOGG matrix. This will put up a plot of the pre- and post- matrix multiplication of the ASET reduced mass matrix by the GSET and ASET modes respectively.

5. Close the plot and the report when satisfied.

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6. Do the same for the Display MACGA.

Interpreting Orthogonality/MAC

Ideally for any orthogonality or cross-orthogonality check, you would like to see all diagonal terms be unity and all off-diagonal terms be zero. In the case of the ORTHOGG matrix, the diagonal terms will be 1.0 by definition; thus the off-diagonal terms are an indication of the acceptability of the reduced mass matrix. That is, that the mass and the distribution of that mass is acceptable with respect to the full model. Off-diagonal values much greater than zero (say 0.1 or larger) indicate a problem with the reduced model in its ability to capture the dynamic effects of the original, fully populated degree of freedom model. More, or a different set of, degrees of freedom may have to be selected.

For the ORTHOGA and MAC matrices, the reduction is ideal if the these are equal to an identity matrix. If this is the case, the ASET modes are identical to the GSET modes. The degree to which these are not unity or zero, respectively, is a measure of the goodness of the ASET modes. Again, you may have to select more or a different set of


degrees of freedom for the ASET, if this check proves unacceptable. A good goal to shoot for is diagonal terms greater that 0.97 and off-diagonal terms less than 0.1 for target modes.

Spike Plots of Eigenvectors, KE, and DPRDo the following (re-visit Spike Plots of Eigenvectors, KE, and DPR (page. 117) if necessary) under the Spike Plot utility in MSC.ProCOR.

1. Compare displacements for Mode 1 GSET versus ASET. Repeat this for as many modes as desired.

2. Compare KE of Mode 1 between the ASET and GSET. Compare relative to All Nodes versus Current Group.

3. Calculate the DPRs for the ASET modes user Pretest ASET... | DPR Calc for Modes 1 through 7 as done in Calculate Drive Point Residues (DPR) (page. 125) for the GSET. Then compare fringe and/or spike plots of Weighted Average DPR.

4. Experiment with Labels Vectors, Keep Previous Plot and Vector Colors, Flip Vector Direction, All Nodes vs. Current Group (use Group | Set Current from pull down menu area).

5. Press the Reset Graphics button before closing this form.

A good reduced model will compare well to the GSET for all these quantities.

Group Energy CalculationsPerform ASET group energy calculations for both KE and ESE as was done in Display and Report Group Kinetic Energy (KE) (page. 118) and Report Group Element Strain Energy (ESE) (page. 123) for the GSET. Compare to the GSET calculations. A good reduced model will compare favorably to the GSET quantities.

Animate Different Modes in Different ViewportsMSC.ProCOR contains an animation utility to help visualize physical mode shapes by animating them together, side by side, in separate viewports.

1. First post the gset_view and the aset_view viewports that were created in the previous exercise. Use Viewport | Post. Remember to use the Ctrl key to select discontinuous selections in a list box.

2. If necessary, post the gset_trace group in the gset_view viewport and the aset_trace in the aset_view viewport. Use Group | Post and remember to make each viewport active before posting.

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3. Select Pretest ASET... | Animate Special. The Animate Setup form will appear.

4. Set up the form as shown here.

• Viewport 1

• gset_view

• pre-g

• Mode 1...

• Eigenvectors, Translational

• No Undeformed

• Deformed Color: Green

• Viewport 2

• aset_view

• pre-a

• Mode 1...

• Eigenvectors, Translational

• No Undeformed

• Deformed Color: Yellow



6. The Animate Special form will appear. Animation does not begin until you press the Start button.

7. Experiment with the Number of Frames, the Number of Cycles, the Speed, and the Scale Factor. Press the Cancel button when you are finished.

ASET ConclusionThe ASET chosen for this example indicates that the first 10 modes are well represented by the ASET. If this were not the case, additional ASET points would be chosen, and the pre-a analysis run would be performed again.

If a new solution is performed, remember to:

Note: To animate both modes in the same viewport, return to the Animate Setup form and change both viewports to be the same. Then press Apply and then Start.

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• Delete the previous results in the Results application (Action | Object = Delete | Result Cases).

• Modify the tracelines as required to visualize the ASET.

• Re-visit the Analysis application setup prior to submittal to make any necessary changes.


3.6 Example 6 - Translate Test DataThe purpose of this exercise is to translate test data from OUTPUT4 format to DMIG cards. An actual test has been performed on the antenna physical prototype model, from which mode shape information has been acquired via accelerometer measurements. These test mode shapes are stored, for the purpose of this exercise, in an OUTPUT4 file called testmodes.op4 which you must copy from the delivery area. The file is located in:

<install_dir>/procor_files/examples/testmodes.op4

Copy it to your working directory that you have been using for the last five exercises.

If necessary, also start MSC.Patran and open the antenna.db database.

Set Up Test Data TranslationActivate MSC.ProCOR, if necessary and then select UFF Utilities... | Translate Test Data from the MSC.ProCOR menu.

The following form appears. Set up the information in this form as follows:

1. Translation Type:

Set this to OP4 File to DMIG.

2. OP4 File INPUT

Press this button and then select the file, testmodes.op4, as the test input file containing the test mode shapes.

3. NASTRAN Bulk File OUTPUT

Press this button and enter the name convert as the MSC.Nastran file that will be created. The .bdf extension will automatically be appended.

4. Aset Names

Accept the default Aset_Nodes.Note: this must be the ASET described in the previous examples. If you chose additional dof, or removed dof, then this example will not work.

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5. Press Apply.

This creates an MSC.Nastran input file, ready for submittal. This analysis job contains special DMAP instructions that read the OP4 file and convert the eigenvectors to DMIG format which will be used later in the test/analysis correlation run.

In most cases, this operation is performed using Universal Files as opposed to OUTPUT2 files. Most test/data acquisition systems have the ability to output mode shape information in the form of Universal Files and some have the ability to put out information into OUTPUT4 files or translate the Universal Files into OUTPUT4 format. Conversion of Universal Files is illustrated in a later exercise.

When the test mode shapes are in OUTPUT4 format, they must be read into MSC.Nastran and subsequently converted to DMIG format by submitting and actual MSC.Nastran analysis using special DMAP provided by MSC.ProCOR. This is automatically done for you and set up in the convert.bdf input file.

Submit the MSC.Nastran Translation RunThe MSC.Nastran input file needs to be submitted to MSC.Nastran. This can be done manually if you wish, or it can be done directly from MSC.Patran.

On completion of the analysis you will end up with one important punch file called convert.pch, containing the test mode shapes in DMIG format.

Add Frequency LabelsThe OUTPUT4 file contains eigenvector data only. In order to get the test data labeled correctly, the frequencies corresponding to each eigenvector must be input manually.

To input the frequencies, do the following:

1. Close down the Analysis application and return to the Translation Setup form under UFF Utilities... | Translate Test Data.

2. Set the Translation Type to Manual Freq Input.

3. Press the Test Freq. Definition... button. This will bring up a form for manually entering frequency data in a spreadsheet.

Note: In this simple example there is a one-to-one correspondence from the test locations to the FEM nodes. When this is not the case, additional steps must be performed which are illustrated in subsequent exercises.

Note: Test data provided as a Universal File contains both eigenvector and frequency data and both are automatically translated.


4. There are 10 mode shapes. Set up the input form as shown above. To enter each frequency, click on the column in the spreadsheet and then enter the frequency in the data box at the top of the spreadsheet labeled Mode n Frequency: where n is the mode number selected.

5. Press the Test Freq. File button and enter the file name testfreq. The .dmi file extension will automatically be appended.

6. Press the Write Freqs. to File button to write the information to the DMI formatted file.

This file, testfreq.dmi, will be referenced later during the test/analysis correlation run.

Note: Before canceling this form, press the Write Freqs. to File button. Failure to do this before closing the session will result in lost data.

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3.7 Example 7 - Test/Analysis CorrelationThe purpose of this exercise is to compare the math model of the antenna to the test data. If necessary, start MSC.Patran, open the antenna.db database and initiate MSC.ProCOR.

Set Up the Test/Analysis RunNow set up the post-test ASET test/analysis correlation run.

1. Select Posttest ASET... | Analysis Setup from the MSC.ProCOR main menu.

Set up the ensuing form as shown:

2. Run Type: Make sure this is set to Posttest ASET.

3. DB/Param/Output Options... All of the defaults in this form should be fine.

4. Reduction Method: set this to Guyan (ASET).

5. Aset Names: set this to Aset_Nodes which should be the only one available, as the ASET has not changed.

6. Compute ORTHOGT: select this.

7. G-Mode Input: select pre-g.phg. This is the file created in the pre test GSET run.

8. Test Mode File Select: select convert.pch.

9. Test Freq. File Select. This is the frequency file that was created in the last exercise by manually inputting the frequencies corresponding to each test eigenvector. This is only for proper labelling. If you leave this as UNSELECTED, then the mode shapes will be labeled Mode 1 = 1. Hz., Mode 2 = 2. Hz, ..., Mode n = n. Hz. Select the DMI formatted file testfreq.dmi.

10. Back Expand Test Modes: this should be selected.


Press the Apply button. The Analysis Setup form will disappear from the screen and will be replaced by MSC.Patran’s standard Analysis application form. A modal form will also appear informing you of the following:

Jobname ‘post-a’ was created. It was associated to Subcase ‘post-a’ which uses the post-a Loadcase (=Default Loadcase). USER ACTION: Select ‘post-a’ in [Available Jobs] AND check the ‘post-a’ under [Subcase Create...] for accuracy.

At this point a new analysis job has been created called post-a. You have no control over the name of the analysis job. Post-test ASET models are always named post-a. If you are ever working with more than one ASET model at the same time, you will have to put them in separate directories.


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Inspect the Post-test ASET Analysis SetupOn the Analysis application, select the post-a job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. OUTPUT2 and OUTPUT4 files assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. Various parameters are set in the Case Control for controlling the DMAP. And finally direct table input (DTI) cards are put in the Bulk Data for proper handshaking between MSC.Nastran and MSC.ProCOR as well as the ASET cards.


The subcase, post-a, is created and associated to the post-a load case. Output Requests... have been set as SPC forces, element strain energy (ESE), and eigenvector data. The post-a subcase is created by copying the default subcase with the default boundary conditions. SPC forces must be calculated for the Kinetic Energy (KE) and Drive Point Residue (DPR) information to be valid.


The post-a subcase is selected for the analysis job.


The job is set up and ready to be run, however, there is one piece of information missing still, the center of gravity. Defining the center of gravity will ensure proper calculation of the Modal Effective Mass (MEM).

Submit the Post-test ASET AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.

If MSC.Nastran is not configured on the same machine that you are running this exercise, or you do not have direct submit access to some MSC.Nastran executable, then set the Action | Object | Method to Analyze | Entire Model | Analysis Deck. This will create the input deck without submitting the job. You can then take the file, called post-a.bdf, to the appropriate machine and run the job. If you do this, don’t forget to bring back all the output result files.

When you submit the job, Full Run or Analysis Deck, you will be asked for overwrite permission. The following files of importance will be created by the analysis:

• post-a.bdf - the MSC.Nastran analysis input deck.

• post-arun.op4 - an OUTPUT4 formatted file containing modal effective mass and frequency information used when displaying the effective mass and making 3D bar charts.

• post-a.op2 - an OUTPUT2 file containing standard output read by MSC.Patran such as the ASET mode shapes, SPC forces, and element strain energy (ESE) for the post-test ASET model.

• posttphi.op2 - an OUTPUT2 file containing the test mode shapes to be read into the database.

• postadpr.op2/posttdr.op2 - an OUTPUT2 file containing drive point residue (DPR) information to be read back into the database for both test modes and ASET model.

• postake.op2/posttke.op2 - an OUTPUT2 file containing kinetic energy (KE) information to be read back into the database for both test modes and ASET model.

Note: The Method is set to Analysis Deck by default. For full submittal via MSC.Patran, be sure to change this to Full Run. Otherwise only the input deck will be created and no analysis will be submitted.

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Read ResultsUnder the MSC.ProCOR menu, select Posttest ASET | OP2 Read Special. The form at the right will be displayed. It should be pre-selected with the Post_A .op2 file. If not, select it then press the Apply button. This action reads and processes six files created by the post-test ASET test/analysis analysis run.

• post-a.op2 - post-test ASET mode shapes and element strain energy

• posttphi.op2 - test mode shapes

• postadpr.op2/posttdpr.op2- drive point residue results for post-test ASET model and test modes

• postake.op2/posttke.op2 - kinetic energy results for post-test ASET model and test modes

At this point you may display the test versus analysis mode shapes, similar to that explained in Example 5 - ASET Model Results (page. 145). Or you can compare displacement and KE using spike plots for test and model data.


View Correlation MatricesSelect Posttest ASET... | Post-A MEM, ORTHO, MAC from the MSC.ProCOR menu to display the Posttest Results form.

1. Initially, results from the pre-test GSET and ASET analyses will be available. Press the Read .op4 File button and select the post-arun.op4 file.

2. Go through the form as you have with the pre-test GSET and ASET analyses, displaying the MEM, ORTHO and MAC quantities.

The following quantities are available for plotting:

• MAMTA (A-set MEM) and MEMTT (test MEM) - Modal effective mass for the ASET and the test mode shapes.

• ORTHOTG - cross-orthogonality check of the test modes shapes and the GSET mode shapes (partitioned to ASET size) w.r.t. the analytical mass matrix.

• ORTHOTA - cross-orthogonality check of the test modes shapes and the ASET mode shapes w.r.t. the analytical mass matrix.

• ORTHOTT - orthogonality check of the test mode shapes w.r.t. the analytically reduced mass matrix.

• MACTA - modal assurance criteria of test versus analytical ASET mode shapes

• MACTT - modal assurance criteria of test versus test modes shapes.

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The plots should be similar to these:

Comparison of the MEM for the ASET and test modes above tells us how well the dominant modes from the model match up with dominant modes from the test. One should not necessarily expect a perfect match, but the trend should be similar. A poor match will indicate either a poor analytical mass matrix or a poor correlation.


The ORTHOTA matrix is a better indicator of correlation:

Ideally for any orthogonality or MAC check, the diagonals should be unity and the off-diagonals should be zero for perfect correlation. By visual inspection of the ORTHOTA and the MACTA matrices, it can be seen that this is far from the case. It does not appear that the model is extremely well correlated to test in that there appears to be many coupled modes.

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The ORTHOTT tells us how well represented is the analytically reduced mass matrix. Poor ORTHOTT matrices can indicate that there is either something wrong with the ASET reduced mass matrix (not enough point were kept) or something may be wrong with the test mode shapes, such as crossed wires measuring incorrect degrees of freedom.

The MACTT matrix will indicate the independence of one test mode to another. By definition, the diagonal terms will be 1.0 so off diagonal terms larger than this are important. If the MACTT matrix indicates high off-diagonal terms, then the test modes may be suspect, particularly for closely spaced modes.


3.8 Example 8 - Model UpdatesAfter reviewing the results from the test/analysis correlation run of the antenna model, you have the following question:

Why does the test-analysis model have so many coupled modes?

Consider the following scenario:

The “right” side of the antenna calls for 0.100 +/- 0.015 sheet, and the “left” side calls for 0.110 +/- 0.015 sheet. Realizing that these were so close, the procurement officer also asked for bids on 0.105 +/- 0.010 sheet. He put out bids for all three sizes and received back the lowest bid for 1 sheet of 0.105 (nominal) material. The manufacturer was good and all dimensions for the sheet were precisely nominal. When the inspector inspected the “as-built” assembly, all items were within tolerance. Having no way of knowing this, the analyst continued to use “nominal design dimensions” for his model. After seeing the close coupling, and doing some investigation, the analyst discovered the reality of the situation.

Update the model and re-perform the post-a run based on this new knowledge.

Modify PropertiesBefore the post-a run can be re-submitted, we must change the properties. With the antenna model open in MSC.Patran, go to the Properties application:

1. Select Properties from the application switch on the main MSC.Patran form.

2. Set the Action to Modify.

3. Find the property called t0p10 (stands for t0.10) and select it from the Select Prop. Set to Modify list box.

4. The Input Properties form will appear. Change the Thickness value to 0.105 inches.

5. Press the Apply button on the Element Properties form.

6. Repeat this operation for the property called t0p11 also.

Delete Results CasesThis step is not necessary, but highly recommended so as to avoid confusion.

Go to the Results application and delete all Result Cases associated with the post-a job.

1. Select Results from the application switch on the main MSC.Patran form.

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2. Set the Action | Object to Delete | Results Cases.

3. Select all Result Cases that begin with the following prefixes:

• post-a

• POSTTPHI

• Post-A-KE

• Post-T-KE

• Post-A-DPR

• Post-T-DPR

4. Press the Apply button on the Results form.

Re-submit the Test/Analysis Correlation JobGo to the Analysis application.

1. Select Analysis from the application switch on the main MSC.Patran form.

2. Set the Action | Object | Method to Analyze | Entire Model | Full Run. Or set the Method to Analysis Deck if you plan on submitting the job manually.

3. Click on the post-a job in the Available Jobs list box.

4. Press the Apply button to re-submit the job. Answer Yes to any overwrite questions asked.

Re-read Output ResultsUnder the MSC.ProCOR menu, select Posttest ASET | OP2 Read Special. The form that appears should be pre-selected with the Post_A .op2 file. If not, select it then press the Apply button to re-read the results.


Review Correlation MatricesNo go back to View Correlation Matrices (page. 169) from the last exercise and review the results again. Note the ORTHOTA and the MACTA matrices plotted below. Compared to the previous non-updated model, the correlation now looks very good.

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Bad Accelerometer DataNext, consider bad test data. Suppose that there were bad accelerometer data for all the accelerometers on Nodes 39, 49, and 61.

1. Select Posttest ASET... | Aset Utilities from MSC.ProCOR menu.

2. Press the Read ASET from File button and select the antenna.aset file that was previously created.

3. Turn OFF all Degrees of Freedom toggles.

4. Now graphically select the nodes or type in Node 39 49 61 literally into the Select Node: select data box.

5. Press the Apply button. Note that the label above the Apply button will change from:

• [Total dof selected: (126)]

to

• [Total dof selected: (117)]

6. Save the new ASET to file again. Press the Write ASET to File button and give the new name as antenna2. The .aset file extension will automatically be appended to the name. This new ASET information is also contained in the Current ASET Name, Aset_Nodes.

7. Cancel the Aset Create form.

8. Open the Analysis Setup under the Posttest ASET... pick.

9. Press the Apply button. It is assumed that Run Type is Posttest ASET, DMIG (.pch) File is set to convert.pch, Aset Names is Aset_Nodes, and Current DMI file is set to testfreq.dmi as before.

10. When the Analysis application appears, select the job post-a and submit the job (press the Apply button).

11. Read the results back in using Posttest ASET... | OP2 Read Special. You should probably delete the old results as done in Delete Results Cases (page. 173) before reading them in again to avoid confusion.


12. Process the results again as done in previous exercises.

Note: The mode shapes will continue to show the displacement for the nodes which are no longer in the ASET. This is because these nodes still reside in the test data. In order to eliminate this, remove these points from the tracelines. This may give “ugly” tracelines. These are hints as to how you might go about doing this:

• Group | Modify - to remove ASET point from displayed group

• Finite Elements | Delete - to delete three of the bar elements.

• Finite Elements | Modify | Element | Connectivity - to reassign connectivity nodes to bars

• Properties | Modify | traceline - to reassign PLOTELs to bar elements

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3.9 Example 9 - Model-Model Comparison - Take 1The purpose of this exercise is to show a step-by-step procedure to guide an analyst through a model-to-model comparison/correlation. It is assumed that you have some familiarity with MSC.Patran and MSC.ProCOR before you start this exercise. You should have carefully studied the first seven examples in this Chapter before proceeding.

A comparison of two models will be performed; in this case two wing models:

• A “Coarse” model -- made of 1D bar elements

• A “Fine model -- made of 2D quad elements

The general procedure is outlined here:

• Generate a coarse meshed model

• Choose an ASET

• Generate PLOTELs to connect ASET points

• Generate a reduced model (Guyan reduction)

• Generate a fine meshed model

• Map the coarse meshed model onto the fine meshed model

• Set up model comparison analysis run

• Review results

Create Coarse Meshed ModelStart by copying the following two files to a clean working directory.

<install_dir>/procor_files/examples/make_beam.ses<install_dir>/procor_files/examples/wing_beam.bdf

Start MSC.Patran and open a new database called coarse.db. You may want to use the mscnastran_template as the template database.

Note: Coordinate systems between models are checked, and incompatible coordinate systems are identified with warnings. However, the burden of providing compatible coordinate systems is placed wholly on the user. This example uses the same coordinate systems for each model.


Generate the coarse model by playing the session file make_beam.ses (File | Session | Play).This session file simply reads in the existing wing_beam.bdf MSC.Nastran input file to create the model. You should end up with a model that appears to the right.

This operation creates all the geometry, nodes, elements, properties, and boundary conditions. You may investigate these as you see fit before continuing.

Generate ASETInitiate MSC.ProCOR and bring up the Aset Utilities form. This can be invoked from a number of places on the MSC.ProCor menu. It is logically placed under Model to Model... | Aset Utilities as the first operation to be performed in a model-to-model comparison.

1. Select Model to Model... | Aset Utilities.

2. The default Current ASET name is set to Aset_Nodes. Leave this as is.

3. Make sure that the Tx, Ty, and Tz degrees of freedom toggles are ON and that the rotational degrees of freedom are OFF.

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4. Select all the nodes on the mode by placing the cursor in the graphics window and click and drag until all nodes are encompassed by the selection rectangle.

When you do this, you will get warning messages indicating that some of the degrees of freedom are associated with either an SPC set or part of an MPC. These degrees of freedom are not added to the ASET, but all others are, which is what we want. Therefore, you may ignore the warning messages. The ASET will look like the picture to the right. Note that there are no vector (ASET) indicators on the constrained or MPC dependent nodes.

Generate PLOTELsThe plot elements will be used in the subsequent analysis run and are useful in showing the modes shapes of only the ASET degrees of freedom.

Copy the following file into your working directory:

<install_dir>/procor_files/examples/make_plotels_bm.ses

ASET Degrees of Freedom


Play this session file (File | Session | Play) to create the PLOTELS. Study this session file, which creates bar elements between the ASET nodes and assigns PLOTEL properties to them, if you desire. A new group is created called plotel and posted as the current group.

Determine the Center of GravityUse the Tools | Mass Properties utility to find the center of gravity (CG) of the model. Then create Node 999 at the CG using the Finite Elements application (Create | Node | Edit). Review Calculate Center of Gravity (page. 104) if need be.

PLOTEL Representation

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Generate Reduced ModelThe next step is to create a Guyan reduced representation of the coarse meshed model. Follow these steps:

1. Select Model to Model... | Gen. Reduc. Model to bring up the form to the right. This form serves as an Analysis Setup to create an MSC.Nastran analysis input file that will Guyan reduce the model to the ASET size.

2. Set the Reduction Type to Advanced.

3. Under DB/Param/Output Options...

set the Run Method to Full Run

set PARAM,GRDPNT to 999.

Select COARSE_MODEL.SC1 in the Use BC’s from Loadcase listbox.

4. Set the Reduction Method to Guyan (ASET) and select Aset_Nodes.

5. Set the Model Output Format to DMIG (.pch/.dmig).

6. Accept all other defaults on this form and press Apply.

The Analysis Setup form will disappear from the screen and will be replaced by MSC.Patran’s standard Analysis application form. A modal form will also appear informing you of the following:

Jobname ‘gen_maapha’ was created. It was associated to Subcase ‘Default’ which uses the Default Loadcase. USER ACTION: Select ‘gen_maapha’ in [Available Jobs] AND check the ‘Default’ under [Subcase Create...] for accuracy.

At this point a new analysis job has been created called gen_maapha. You have no control over the name of the analysis job. Guyan reduced models are always named gen_maapha. If you are ever working with more than one reduced model at the same time, you will have to put them in separate directories.

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Inspect the Reduced Model Analysis SetupOn the Analysis application, select the gen_maapha job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. A DMI file assignments is made in the FMS portion. The proper DMAP control is included in the Executive data. And the ASET is included in the Bulk Data section as well as some PARAM cards.


The Default subcase is left as-is and is associated with the Default Load Case.


The Default subcase is selected for the analysis job.

Submit the Model Reduction AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.


If MSC.Nastran is not configured on the same machine that you are running this exercise, or you do not have direct submit access to some MSC.Nastran executable, then set the Action | Object | Method to Analyze | Entire Model | Analysis Deck. This will create the input deck without submitting the job. You can then take the file, called gen_maapha.bdf, to the appropriate machine and run the job. If you do this, don’t forget to bring back all the output result files.


• gen_maapha.bdf - the MSC.Nastran analysis input deck to create the reduce model.

• gen_maapha.pch - a punch file of DMIG formatted cards containing the eigenvectors and mass information.

• gen_maapha.op2 - an OUTPUT2 file containing standard output read by MSC.Patran such as mode shapes and SPC forces.

• lama22.dmi - a file of DMI formatted cards containing the eigenvalues corresponding to each eigenvector for use in the subsequent comparison.

Generate Fine Meshed ModelEither quit from your current MSC.Patran session (File | Quit) and then start MSC.Patran up again, or close the current database (File | Close).

Open a new database called fine.db. It is recommended to use the mscnastran_template as the template database.

Copy the following files to your directory:

<install_dir>/procor_files/examples/make_quad.ses<install_dir>/procor_files/examples/wing_quad.bdf

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Run this session file (File | Session | Play), which reads the wing_quad.bdf MSC.Nastran input file, to create the nodes, elements, properties, and boundary conditions and a number of convenient groups. You should see the following model on your screen.

Map the Course Mesh to the Fine MeshThe next step is to take the information from the course meshed beam model and map it onto the fine meshed model. Follow these steps.

Open the form that does the mapping. Select Model to Model... | BDF match utility from the MSC.ProCOR menu.

The form below appears. This form will read coordinate systems, nodes, and plot elements from the course meshed model’s MSC.Nastran input file. It will also re-map (renumbers nodes) DMIG (eigenvectors) and create DMI frequency input. Since the coordinate system between the two models is identical, it is not necessary to Read Coord. Systems.


Read Nodes.

1. Set the Translation Type to Read Nodes.

2. Press the BDF File INPUT button and select the coarse meshed model input file, gen_maapha.bdf.

3. Turn ON the Create Node Map toggle. This will create a mapping array between the external bulk data and the nodes in the database. You do not need to specify a Map File... at this time

4. Turn ON the Use bdf Aset Nodes Only toggle. This will map only the nodes found in the ASET of the coarse meshed model.

5. Set the Model Node Search to Current Group Nodes.

6. Set the Node Translate Options to Plot Markers only. The nodes from the external input file will not be imported into the currently opened database, but markers will be generated for visualization purposes.

7. Press Apply.

The first thing that happens is that a new ASET is created called bdf_translated_aset. The Aset Utilities function is called and the form appears. You will be able to see the markers on the graphics screen corresponding to the locations.

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You should inspect the ASET graphically to make sure it looks reasonable as shown below.


8. The External to Internal Map Form will also appear. The spreadsheet is filled in with the node mapping. By default a map named BDF Translate Node Map will be automatically stored on the database for future use. Set the Store MAP name: databox to ASET node map and Apply.

9. Since the beam model had PLOTELs connected to nodes that had SPCs, those points need to be mapped also. Turn OFF the Use bdf Aset Nodes Only toggle and press Apply again to re-do the operation. This time no ASET will be created but all nodes from the PLOTELs connectivity will be read and mapped.

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Read PLOTELs

Now read the actual PLOTELs from the external, coarse meshed model.

1. Set the Translation Type to Read Plotels.

2. Make sure the Selected BDF File is still set to gen_maapha.bdf.

3. Turn ON the Use Node Map toggle.

4. Make sure the Current map file is BDF Translate Node Map.

5. The Traceline Translate Options should be set to Create Plotels on Nodes.

6. Press Apply.

This operation will literally read the PLOTELs from the coarse meshed model input file and create bar elements with PLOTEL properties in the fine meshed model. A group called BDF_Plotels is created: this group contains the plotel elements and the nodes.


Re-map DMIG

Now re-map the DMIG cards from the external, coarse meshed model.

1. Set the Translation Type to Remap DMIG.

2. Make sure the Selected .pch File is set to gen_maapha.pch.

3. Turn ON the Use Node Map toggle.

4. The Current MAP Name can be either BDF Translate Node Map, or Aset node map.

5. Press Apply.

This operation creates a new punch file with re-mapped DMIG cards representing the eigenvectors from the ASET reduced coarse model. The re-mapping is nothing more than a renumbering of the nodes to correspond to the proper point in the fine meshed model. A new file called remapped_dmig.pch is created. Cancel the form when done.

Determine Center of Gravity of Fine Meshed ModelUse the Tools | Mass Properties utility to find the center of gravity (CG) of the model. Then create Node 9999 at the CG using the Finite Elements application (Create | Node | Edit). Review Calculate Center of Gravity (page. 104) if need be.

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Set Up Model Comparison Analysis

The next step is to set up the model comparison analysis run. Follow these steps:

1. Select Model to Model... | Model Comp Setup to bring up the form to the right. This form serves as the Analysis Setup to create an MSC.Nastran analysis input file that compares the fine meshed model to the coarse meshed model.

2. Set the Type to Advanced.


3. Set the Model 1 Options to Internal. This signifies that Model 1 resides in the MSC.Patran database.

4. Set the Model 2 Options to External dmig. This signifies that Model 2 resides in an external DMIG punch file (the eigenvector and mass data that is).

5. Set the Reduction Method for Model 1 to Guyan (ASET). The selected Aset Name should be bdf_translated_aset which is the internal ASET created by reading the ASET from the external model.

6. Set the Model 2 Shape File to remapped_dmig.pch which is the coarse meshed model eigenvector and mass matrix file with the nodes renumbered to match the internal (fine mesh) model.

7. Set the Mode 2 Freq. File to lama22.dmi which is the DMI formatted frequency information corresponding to the eigenvectors of the coarse meshed, external model.

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8. Press the DB/Param/Output Options... button.

On the options form, set Run Method to Full Run; PARAM GRDPNT to 9999; and select DEFAULT.SC2 for the loadcase. Press Apply to register these changes and close the form.

9. Press Apply on the modelcomp setup form.



Jobname ‘Model_Comp’ was created. It was associated to Subcase ‘modlcomp’ which uses the Default Loadcase. USER ACTION: Select ‘Model_Comp’ in [Available Jobs] AND check the ‘modelcomp’ under [Subcase Create...] for accuracy.

At this point a new analysis job has been created called Model_Comp. You have no control over the name of the analysis job. Model comparison jobs are always named Model_Comp. If you are ever working with more than one comparison at the same time, you will have to put them in separate directories.


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Inspect the Model Comparison Analysis SetupOn the Analysis application, select the Model_Comp job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. OUTPUT2 and OUTPUT4 file assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. Various PARAM cards are set in the Case Control. And the ASET is included in the Bulk Data section as well as DTI cards to ensure proper handshaking between MSC.Patran and MSC.Nastran.


The model_comp subcase is created and is associated with the model_comp Load Case.


The model_comp subcase is selected for the analysis job.


Submit the Model Compare AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.



• model_comp.bdf - the MSC.Nastran analysis input deck to do the model comparison.

• modl_1_2.op4 - an OUTPUT4 file containing the correlation matrices for MEM, ORTHO, and MAC displays.

• modl_1_kea.op2 - the kinetic energy (KE) for Model 1.

• modl_1_pha.op2 - the mode shapes for Model 1.

• modl_2_kea.op2 - the KE for Model 2.


Read Output ResultsUnder the MSC.ProCOR menu, select Model to Model... | OP2 Read Special. The form that appears should be pre-selected with the ModelComp .op2 file. If not, select it then press the Apply button to read the results.

Try comparing the mode shapes for the two different models by overlaying deformation plots or animations. You must use the group BDF_Plotels to get a proper display. Do this in the Results application or use the Animate Special or Spike Plot utilities.


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Display MEM, ORTHO, MAC MatricesUnder the MSC.ProCOR menu, select Model to Model... | Model-Model MEM, ORTHO, MAC. You must first read in the modl_1_2.op4 file to activate all the options on this form.

1. Press the Read Model Comp .op4 file button. Select the above indicated file.

2. Systematically press each of the other buttons on the form to display MEM, ORTHO and MAC calculated matrices. ORTHO12 and ORTHO21 are cross-orthogonality matrices with respect to Model 2 and Model 1’s reduced mass matrices respectively.

3. Press the PLOT button on each report form to view a 3D bar chart. You should see plots similar to those below.

Note that mode 1 demonstrates the best correlation, which is the first bending mode. Note that the other modes show considerable coupling. This is likely due to the fidelity of the pylon models between the coarse model and the fine model. A review of the mode shapes indicates similar modes, but not the same behavior. The MAC is particularly poor in this case, indicating that the modes could not be considered independent based on this criteria. In reality, one of these models may have been used by the dynamics group, while the other could be an internal loads model. At face value, without the benefit of test data, the “fine” model is probably more accurate.


This type of comparison can be important for companies who develop both “coarse” and “fine” models for different purposes. This can point out possible deficiencies in modeling techniques.

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3.10 Example 10 - Model-Model Comparison - Take 2This exercise is intended to be a step-by-step procedure to guide an analyst through a model-to-model comparison/correlation for simple model changes. It is assumed that you have some familiarity with MSC.Patran and MSC.ProCOR before you start this exercise. You should have carefully studied the first seven examples and the previous model-to-model comparison example in this Chapter before proceeding.

The following notes are made:

• In this example, ASET reduction is not used. Therefore, the two models must have the same grid points.

• This type of model-to-model comparison can be used in Fail Safe scenarios to assess modal characteristic impacts of failed connections, i.e., removing elements.

• Also, these types of comparisons can be used to assess modal effects of proposed physical or material property changes (aluminum versus steel versus composite, etc. or beams with different cross sections).

A comparison of two models will be performed; in this case, a goal post model with two material proposals:

• #1) aluminum

• #2) steel

The general procedure is outlined here:

1. Generate typical model

2. Generate modes and matrices needed for comparison

3. Modify model

4. Could be physical or material property change, or removal of elements (but not nodes) for fail safe

5. Set up model comparison analysis run

6. Review results

Create Preliminary ModelStart by copying the following file to a clean working directory.

<install_dir>/procor_files/examples/goalpost.ses

Start MSC.Patran and open a new database called goalpost.db. You may want to use the mscnastran_template as the template database.


Generate the coarse model by playing the session file goalpost.ses (File | Session | Play). You should end up with a model that appears below.

This operation creates all the geometry, nodes, elements, properties, and boundary conditions. You may investigate these as you see fit before continuing.

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Generate Baseline ModesThe next step is to calculate modes and the matrices of the baseline model, in this case, the model made of aluminum. Follow these steps:

1. Select Model to Model... | Gen. Reduc. Model to bring up the form to the right. This form serves as an Analysis Setup to create an MSC.Nastran analysis input file that will generate modes and the mass matrix.

2. Leave the Type at Simple.

3. Press the DB/PARAM/Output Options... and set the Run Method to Full Run; and PARAM,GRDPNT to 999. Press Apply on the options form to register the changes.


4. Accept all other defaults on the setup form and press Apply.


Jobname ‘gen_maapha’ was created. It was associated to Subcase ‘gen_maapha’ which uses the gen_maapha Loadcase. USER ACTION: Select ‘gen_maapha’ in [Available Jobs] AND check the ‘gen_maapha’ under [Subcase Create...] for accuracy.

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At this point a new analysis job has been created called gen_maapha. You have no control over the name of the analysis job. Baseline mode analyses are always named gen_maapha. If you are ever working with more than one baseline model at the same time, you will have to put them in separate directories.


Inspect the Baseline Analysis SetupOn the Analysis application, select the gen_maapha job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. A DMI and other file assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. And certain PARAM cards are included in the Bulk Data section.


The Default subcase is left as-is and is associated with the Default Load Case.


The Default subcase is selected for the analysis job.


Submit the Baseline AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.



• gen_maapha.bdf - the MSC.Nastran analysis input deck to create the reduce model.

• maapha.op4 - an OUTPUT 4 file containing the eigenvectors and mass information.

• gen_maapha.op2 - an OUTPUT2 file containing standard output read by MSC.Patran such as mode shapes and SPC forces.

• lama22.dmi - a file of DMI formatted cards containing the eigenvalues corresponding to each eigenvector for use in the subsequent comparison.

Modify Existing Model

1. Go to the Properties application on the main MSC.Patran application switch.

2. Set the Action to Modify and select the only property, thk010.

3. Change the Material from alum to steel.


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4. Press OK and then Apply.


Set Up Model Comparison AnalysisThe next step is to set up the model comparison analysis run. Follow these steps:

1. Select Model to Model... | Model Comp Setup to bring up the form to the right. This form serves as the Analysis Setup to create an MSC.Nastran analysis input file that compares the aluminum model to the steel model.

2. Leave the Type at Simple.

3. Set the Model 2 Shape File to maapha.op4 which is the aluminum model eigenvector and mass matrix file.

4. Set the Model 2 Freq. File to lama22.dmi which is the DMI formatted frequency information corresponding to the eigenvectors of the aluminum, external model.

5. Press the DB/Param/Output Options... button. The parameter form should have all the proper defaults picked out. You can close this form after reviewing it.

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6. Accept all other defaults on this form and press Apply.


Jobname ‘Model_Comp’ was created. It was associated to Subcase ‘model_comp’ which uses the model_comp Loadcase. USER ACTION: Select ‘Model_Comp’ in [Available Jobs] AND check the ‘model_comp’ under [Subcase Create...] for accuracy.


At this point a new analysis job has been created called Model_Comp. You have no control over the name of the analysis job. Model comparison jobs are always named Model_Comp. If you are ever working with more than one comparison at the same time, you will have to put them in separate directories.


Inspect the Model Comparison Analysis SetupOn the Analysis application, select the Model_Comp job from the Available Jobs list box. Systematically open the subordinate forms to see how the job has been set.



2. Solution Type...



Direct Text Input into the FMS, Executive, Case Control, and Bulk Data are automatically set. OUTPUT2 and OUTPUT4 file assignments are made in the FMS portion. The proper DMAP control is included in the Executive data. Various PARAM cards are set in the Case Control. And DTI cards, to ensure proper handshaking between MSC.Patran and MSC.Nastran, are placed in the Bulk Data section.


The model_comp subcase is created and is associated with the model_comp Load Case.


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The model_comp subcase is selected for the analysis job.

Submit the Model Compare AnalysisAt this point, you may press the Apply button on the Analysis application with the Action | Object | Method set to Analyze | Entire Model | Full Run. The job setup is “run-ready,” meaning all the information is set for the job to be submitted directly to MSC.Nastran with no manual edits to the input deck necessary.



• model_comp.bdf - the MSC.Nastran analysis input deck to do the model comparison.

• modl_1_2.op4 - an OUTPUT4 file containing the correlation matrices for MEM, ORTHO, and MAC displays.

• modl_1_kea.op2 - the kinetic energy (KE) for Model 1.


• modl_2_kea.op2 - the KE for Model 2.


Read Output ResultsUnder the MSC.ProCOR menu, select Model to Model... | OP2 Read Special. The form that appears should be pre-selected with the ModelComp .op2 file. If not, select it then press the Apply button to read the results.

Try comparing the mode shapes for the two different models by overlaying deformation plots or animations. Do this in the Results application or use the Animate Special or Spike Plot utilities.



Display MEM, ORTHO, MAC MatricesUnder the MSC.ProCOR menu, select Model to Model... | Model-Model MEM, ORTHO, MAC. You must first read in the modl_1_2.op4 file to activate all the options on this form.

1. Press the Read Model Comp .op4 file button. Select the above indicated file.

2. Systematically press each of the other buttons on the form to display MEM, ORTHO and MAC calculated matrices. ORTHO12 and ORTHO21 are cross-orthogonality matrices with respect to Model 2 and Model 1’s reduced mass matrices respectively.

3. Press the PLOT button on each report form to view a 3D bar chart. You should see plots similar to those below.

On the face of it, these models look to be perfectly correlated. In fact, the mode shapes are identical, but the frequencies an total mass are different. If there is a frequency range which to avoid (say rotating machinery with a known forcing frequency, or a special control system maneuver), one model may be chosen over another. This example is intended to help the reader with the process of comparing 2 models, not necessarily the results of this particular comparison.

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3.11 Example 11 - Universal File TranslationThis last example uses an actual, but simple, modal test/analysis correlated model. It is a test stand setup, from which an FE model has been created. The test stand itself was modally tested with the idea that the analytical model would be correlated to test and updated, if necessary, such that it could be coupled onto subsequent FE models. These later FE models would then have the test rig stand as part of the model to simulate its flexibility or stiffness, and the analyst could be confident that it was correct, for any subsequent modal tests performed on the test rig.

It is assumed that you are quite familiar with MSC.ProCOR, so only the steps that have not been introduced yet are highlighted in this example. All other steps are only outlined here. If you have any problems, review the previous example problems.

Create the Analytical ModelCopy the following file to a working directory:

<install_dir>/procor_files/examples/teststand.dat

Invoke MSC.Patran, open a new database called teststand.db and import this MSC.Nastran input deck (File | Import | Model | MSC.Nastran Input). You may have to change the file browser The model below should be apparent in the viewport.


Map the Test Model Information to the Analytical ModelTest Universal Files contain not only the mode shapes and frequencies as measured by test, but they also contain coordinate system, node, traceline, and ASET information. In this section we will read this information from the Universal file:

<install_dir>/procor_files/examples/testdata.unv

Open the UFF Utilities... | Geometry Match. The form that appears is very similar to the BDF mapping utility discussed in Example 9 - Model-Model Comparison - Take 1 (page. 178).

Coordinate Systems

When the form appears, perform the following steps:

1. Translation Type to Read Coord. Systems.

2. Press the UFF File INPUT button and select testdata.unv in the file selection box.


4. Since the coordinate systems are already in the MSC.Patran database, answer NO to overwrite the existing coordinate systems.

Note: This is not actually a necessary step in this particular example because the coordinate systems in the model are the same as the coordinate systems in the universal file.

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Read Nodes

To read the nodes from the universal file:

1. Next set the Translation Type to Read Nodes.

2. The UFF File Input should still be set to testdata.unv.

3. Turn the Create Node Map toggle ON.

4. Turn the Find All Equid. Matches toggle ON.

5. Accept all other defaults on this form, especially Plot Markers only. Press the Apply button.

Graphically you will see the nodes in the Universal File being mapped to nodes the FE model. A mapping spreadsheet will appear.


Node Mapping

When the nodes were read in, a map was generated between the universal file and the model as shown to the right. Usually we would be satisfied with this mapping and there would be no further action required.

However, the mapping is not quite correct. It turned out that there were model changes between the time the test lab got the original model and the current model.

A true mapping file has been provided in:

<install_dir>/procor_files/examples/uff_node.map

Copy this file to your directory.

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Change the Action to Read Map from File. Then press the Define File button and

select uff_node.map. Pressing the Apply button will load the map into the spreadsheet.

Note: At this point, the map has not been saved on the database and will not be used in subsequent operations


To store the new map, change the Action to Store New Map.

Then, in the Store MAP name databox, type Actual Map, then press Apply. By doing this, the proper map will be available to read tracelines and convert the test data.

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Read Trace Lines

To read the tracelines from the universal file:

1. Set the Translation Type to Read Trace Lines.


3. Turn the Use Node Map toggle ON.

4. The Current MAP Name should be Actual Map.

5. The Generate Option should be set to Create Plotels on Nodes.


This operation automatically takes the traceline information from the Universal File and creates bar elements with PLOTEL properties. It also creates a group called UFF_Tracelines. Go under Group | Post and post only this group.


Read ASET Dof

The ASET can also be derived from the universal file. To read the ASET dof:

1. Set the Translation Type to Read Aset Dof.


3. Turn the Use Node Map toggle ON.

4. The Current MAP Name should be Actual Map.


There are several possible ASET dofs on this universal file. You will be queried with something like:

The correct respnse is NO until you get to Coordinate Trace 5 -- ALL STBD RESPONSES, then accept this one.

This operation automatically creates an ASET for us called UFF_coord_trace_derived that has properly mapped the Universal File node locations to those of the FE model. For this reason, we never have to use the Aset Utilities form. The form appears during this operation only to show you that the ASET has been created. You can Cancel from the Aset Utilities form and the Universal File Utilities form.

Run the Pre-test GSET AnalysisOpen Pretest GSET... | Analysis Setup. Set the Mode Shape Output to DMIG (.pch/.dmig) and press the Apply button.

When the Analysis application appears, submit the job pre-g. However, before doing so, calculate the center of gravity of the model using the Tools | Mass Properties... utility. Create a Node 999 at this location using the Finite Elements application (Create | Node | Edit). For job pre-g, on the Analysis Setup | DB/Param/Output Options set PARAM, GRDPNT to 999.

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When the analysis is done, open Pretest GSET... | OP2 Read Special to read in the pre-g analysis results. Investigate any results as you see fit (modes, DPR, KE, ESE, MEM).

Run the Pre-test ASET AnalysisOpen Pretest ASET... | Analysis Setup. Set the Mode Shape Input to DMIG (.pch/.dmig). Select the Modeshape file created from the pre-g GSET analysis: pre-g.pch. Select the ASET, UFF_coord_trace_derived, which was created from querying the Universal file containing the test modes, frequencies, and geometry. Press the Apply button.

When the analysis is done, open Pretest ASET... | OP2 Read Special to read in the pre-a analysis results. Investigate any results as you see fit (modes, DPR, KE, ESE, MEM, ORTHO, MAC).

Translate the Test Modes from the Universal FileOpen UFF Utilities... | Translate Test Data. Set the Translation Type to UFF to DMIG. Select the same UFF file as before: testdata.unv. Turn ON the Remap Grids toggle and select the uff_node.map file by pressing the Apply button on the UFF Map form. This file was created when the Universal File ASET information was queried and maps the test locations to the nodes of the FE model. Press the Apply button on the Translation Setup form.

The translation is quick and creates the following two files that contain the eigenvectors and frequencies in DMIG and DMI format respectively: test_shapes.pch, test_freqs.dmi.

Run the Post-test ASET AnalysisOpen Posttest ASET... | Analysis Setup. Select the Test Modeshape File: test_shapes.pch. Select the Test Freq. File: test_freqs.dmi. Select the UFF_coord_trace_derived ASET name. Press the Apply button.


When the analysis is done, open Posttest ASET... | OP2 Read Special to read in the post-a analysis results. Investigate any results as you see fit (modes, DPR, KE, ESE, MEM, ORTHO, MAC). Below is plotted the ORTHOTA matrix. As you can see the first few modes correlate very well.

Note: There are more test modes than there are analytical modes (that were computed, at least). Try using the mode filter for the ORTHOTA 3D bar chart to plot only the first 10 test modes. This will give a cleaner looking plot.

I N D E XMSC.ProCOR User’s Guide

Aaccelerometer locations, 9, 14analysis setup, 26

a-set, 29g-set, 27model to model, 88reduced model, 79

animation, 65a-set, 10

utilities, 59a-set analysis setup, 29

BBDF match utility, 82

Ccorrelation, 9, 15, 16cross-orthogonality checks, 9, 15

Ddegree-of-freedom sets, 10degrees of freedom, 60DMAP Alters, 9DMI, 74, 86DMIG, 74, 86drive point residue (DPR), 9, 14

calculation, 39

Eelement strain energy (ESE), 43

example problemsASET model, 128ASET Results, 145GSET model, 95GSET Results, 106model updates, 173model-model comparisons, 178, 200test/analysis correlation, 164translate test data, 161Universal File Translation, 212views and groups, 140

excitation locations, 9, 14

Ffilter, 57frequencies, 77full model, 27

Gg-set, 10g-set analysis setup, 27Guyan reduction, 79

Kkinetic energy (KE), 9, 13

group energy, 43table, 41

Mmeasurement locations, 9modal assurance criteria (MAC), 9, 16

INDEX224

modal effective mass (MEM), 9, 11, 55modal effective reaction (MERXN), 9, 12, 55mode shape plots

animate, 65model comparison setup, 88model to model comparison, 79

Nnewlink

F1_MEM_ORTHO_MAC_DISPLAY, 54

Oorthogonality checks, 9, 15OUTPUT2 files

file names, 37read, 36

PPCL, 9

Rreduced model, 29, 79references, 18rephase results, 68results

rephase, 68

Sshaker locations, 9, 14spike plot, 57

Ttest frequencies, 77

translate, 75test mode shapes

animate, 65translate, 74

translate test data, 74

Uuniversal file utilities, 69utilities

a-set, 59BDF match, 82universal file, 69

Vvector plot, 57

msc.procor 2006 user's guide

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