msc nastran 2008 r1 release guide

MSC Nastran 2008 r1

Release Guide

CorporateMSC.Software Corporation2 MacArthur PlaceSanta Ana, CA 92707 USATelephone: (800) 345-2078Fax: (714) 784-4056

EuropeMSC.Software GmbHAm Moosfeld 1381829 Munich, GermanyTelephone: (49) (89) 43 19 87 0Fax: (49) (89) 43 61 71 6

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Worldwide Webwww.mscsoftware.com

DisclaimerMSC.Software Corporation reserves the right to make changes in specifications and other information contained

in this document without prior notice.

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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This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or

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This software may contain certain third-party software that is protected by copyright and licensed from

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Applications and System Integration Inc.

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MSC Nastran 2008 r1 Release Guide

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A Word About Prerelease Features x

List of Books xi

Technical Support xii

Internet Resources xiv

1 Overview of MSC Nastran 2008 r1

Overview 2

Optimization 2

Aeroelasticity 2

Symbolic Subsitution 2

List of Errors Resolved 3

List of Example Problems for the MSC Nastran 2008 r1 Release 3

List of MSC Nastran Documents Released with MSC Nastran 2008 r1 3

2 Implicit Nonlinear

Implicit Nonlinear - SOL 600 6

Support of Large Grid and Element IDs 6

Multiple RFORCE Entries in the Same Subcase 6

BCONTACT Case Control Command Clarification 6

Generalized Alpha Dynamic Integration Method 12

MATVP Material Property Entry 12

MATSMA Shape Memory Alloy Material Property Entry 12

Nonlinear Elastic Orthotropic Materials 13

Composite Integration Methods to Reduce Computer Time 13

New SOL 600 Bulk Data Entries and Parameters 14

3 NVH and Acoustics

NVH Enhancements 18

ACMS with Acoustic External Superelement Creation 18

Multiple RANDOM Looping 18

Sparse OUTPUT4 Format for External Superelement Creation 18

Table of Contents


==

iv

Binary op2 and op4 Compatibility Robustness 18

Merged Superelement Results 19

4 Numerical Methods and High Performance Computing

Factor Matrix Caching for Lanczos 22

Introduction 22

Benefits 22

Method and Theory 22

Inputs 22

Outputs 22

Guidelines and Limitations 23

Demonstration Examples 23

New TAUCS Indefinite Solver Improves Lanczos Performance 24

Introduction 24

Benefits 24


Inputs 24

Outputs 24



Shared Memory Parallel (SMP) Scalability Improvements for Static

Analysis 26

Introduction 26

Benefits 26


Inputs 26

Outputs 26

Guidance and Limitations 26


New MAXRATIO Information Output 28

Introduction 28

Benefits 28


Inputs 28

Outputs 28


Demonstration Example 29

Example Input Data 29

Example Output 31

New SPARSESOLVER MDTSTATS Information Output 32

vContents

Introduction 32

Benefits 32


Inputs 32

Outputs 32


Demonstration Example 33

Example Input Data 33

Example Output 35

5 Upward Compatibility

TEMPERATURE Case Control Command 38

Improvements in Fluid Eigenvalue Analysis 40

FLUID GRID Points and Partitioning 41

Distributed Memory Parallel (DMP) Diagnostic Messages 43

System Information Message (SIM) 6916 44

6 Optimization

Enhancements in DRESP3 46

Introduction 46

Benefits 46

User Inputs 46

Output 51


Examples 53

Topometry Optimization 56

Introduction 56

Benefits 56

Input 57

Output 59


Example 1 - Three-bar Truss (tomex1.dat) 59

Input 61

Output 63

Example 2 – Car Model Topometry Design 63

Topography (Bead or Stamp) Optimization 65

Introduction 65


==

vi

Benefits 65

Input 65

Outputs 68


Example 3 – A Square (togex1.dat) 69

Input 70

Output 70

Randomization of an Input Data File 71

Introduction 71

Benefits 71

Input 71

Output 72


Random Elimination of Element Types 73

Introduction 73

Benefits 73

Input 73

Output 73


Enhancements in SOL 200 Optimization 74

Introduction 74

Benefits 74

Input 74

Example 75

Output 76

Guidelines 77

Limitations 77

7 Aeroelasticity and Rotor Dynamic Improvements

A New Aerodynamic Interpolation Method 82

Introduction 82

Inputs 82

Outputs 82


Examples 83

External Spline Server 85

Introduction 85

Inputs 85

API Changes 85

viiContents

Sparse Matrix Format 86

Upgrading an Existing Spline Server 86

Blade Vibration Analysis 87


==

viii

The 2005 New Template

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å A Word About Prerelease Features

å List of Books

å Technical Support

å Internet Resources


A Word About Prerelease Featuresx

A Word About Prerelease Features

MSC Nastran 2008 r1 may contain a number of features that have been labeled as “prerelease.”

A prerelease feature or enhancement is defined as a feature or enhancement that has not yet completed

MSC’s exhaustive verification and validation (V and V) testing and qualification process. Therefore,

prerelease features are to be used at the client’s own risk.

xiPreface

List of Books

Below is a list of some of the MD Nastran and MSC Nastran documents. You may order any of these

documents from the MSC.Software BooksMart site at http://store.mscsoftware.com/.

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ç Installation and Operations Guide

ç Release Guide

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ç Quick Reference Guide

ç DMAP Programmer’s Guide

ç Reference Manual

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ç Getting Started

ç Linear Static Analysis

ç Basic Dynamic Analysis

ç Advanced Dynamic Analysis

ç Design Sensitivity and Optimization

ç Thermal Analysis

ç Numerical Methods

ç Aeroelastic Analysis

ç Superelement

ç User Modifiable

ç Toolkit

ç Implicit Nonlinear (SOL 600)

ç Explicit Nonlinear (SOL 700)

ç MD User’s Guide - Application Examples

ç Topology Optimization

ç SCA Service Guide

ç User Defined Services


Technical Supportxii

Technical Support

For help with installing or using an MSC.Software product, contact your local technical support services.

Our technical support provides the following services:

• Resolution of installation problems

• Advice on specific analysis capabilities

• Advice on modeling techniques

• Resolution of specific analysis problems (e.g., fatal messages)

• Verification of code error.

If you have concerns about an analysis, we suggest that you contact us at an early stage.

You can reach technical support services on the web, by telephone, or e-mail.

tÉÄ Go to the MSC.Software website at www.mscsoftware.com, and click on Support. Here you can find a

wide variety of support resources including application examples, technical application notes, training

courses, and documentation updates at the MSC.Software Training, Technical Support, and

Documentation web page.

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bã~áä Send a detailed description of the problem to the email address below that corresponds to the product you

are using. You should receive an acknowledgement that your message was received, followed by an

email from one of our Technical Support Engineers.

United States

Telephone: (800) 732-7284

Fax: (714) 784-4343

Frimley, CamberleySurrey, United Kingdom

Telephone: (44) (1276) 60 19 00

Fax: (44) (1276) 69 11 11

Munich, Germany

Telephone: (49) (89) 43 19 87 0

Fax: (49) (89) 43 61 71 6

Tokyo, Japan

Telephone: (81) (03) 6911 1200

Fax: (81) (03) 6911 1201

Rome, Italy

Telephone: (390) (6) 5 91 64 50

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Paris, France

Telephone: (33) (1) 69 36 69 36

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Moscow, Russia

Telephone: (7) (095) 236 6177

Fax: (7) (095) 236 9762

Gouda, The Netherlands

Telephone: (31) (18) 2543700

Fax: (31) (18) 2543707

Madrid, Spain

Telephone: (34) (91) 5560919

Fax: (34) (91) 5567280

xiiiPreface

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The MSC Institute of Technology is the world's largest global supplier of CAD/CAM/CAE/PDM

training products and services for the product design, analysis, and manufacturing markets. We offer

over 100 courses through a global network of education centers. The Institute is uniquely positioned to

optimize your investment in design and simulation software tools.

Our industry experienced expert staff is available to customize our course offerings to meet your unique

training requirements. For the most effective training, The Institute also offers many of our courses at

our customer's facilities.

The MSC Institute of Technology is located at:

2 MacArthur Place

Santa Ana, CA 92707

Phone: (800) 732-7211

Fax: (714) 784-4028

The Institute maintains state-of-the-art classroom facilities and individual computer graphics

laboratories at training centers throughout the world. All of our courses emphasize hands-on computer

laboratory work to facility skills development.

We specialize in customized training based on our evaluation of your design and simulation processes,

which yields courses that are geared to your business.

In addition to traditional instructor-led classes, we also offer video and DVD courses, interactive

multimedia training, web-based training, and a specialized instructor's program.

Course Information and Registration. For detailed course descriptions, schedule information,

and registration call the Training Specialist at (800) 732-7211 or visit www.mscsoftware.com.

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Internet Resourcesxiv

Internet Resources

MSC.Software (www.mscsoftware.com)

MSC.Software corporate site with information on the latest events, products, and services for the

CAD/CAE/CAM marketplace.

Chapter 1: Overview of MSC Nastran 2008 r1 MSC Nastran 2008 r1 Release Guide

1 Overview of MSC Nastran 2008 r1

� Overview


Overview2

Overview

MSC Software is proud to release MSC Nastran 2008 r1. This release of MSC Nastran significantly

advances the multidiscipline capabilities available to you. The following sections briefly describe some

of the major and minor enhancements to MSC Nastran 2008 r1.

Optimization

MSC Nastran has had very powerful optimization routines since it was released in 2006. The

functionality in that release included shape, sizing, and basic topology optimization. MSC Nastran 2007

r1 introduced manufacturing and symmetry constraints for topology optimization. MSC Nastran 2008

r1 extends this functionality in the areas of topography and topometry optimization.

In topography optimization, the nodes on a surface mesh are moved normal to the surface during the

optimization loop to arrive at an optimal shape. In contrast, topometry optimization considers each

element in a design region to have a unique property and it will be modified to achieve an optimal design.

Additional optimization enhancements include:

• Automatic randomization of input variables rapid stochastic analysis set-up,

• Random element elimination for sensitivity studies of spot welds and connectors,

More information on these optimization enhancements can be found in Optimization (Ch. 6).

Aeroelasticity

MSC Nastran 2007 r1 introduced an external spline evaluation capability. This capability has been

enhanced in R3 to support storage of the spline matrix in sparse format. This change allows larger models

to fit into memory.

MSC Nastran 2008 r1 also introduces new capabilities for aeroelasticity analyses. There is a new

aerodynamic interpolation method that interpolates each term in the generalized aerodynamic matrix

individually. Examples for using this new interpolation method are given in Aeroelasticity and Rotor

Dynamic Improvements (Ch. 7).

Symbolic Subsitution

Using the new Symbolic Substitution feature, you can run multiple analyses on an input file, while

modifying fields automatically. Using Symbolic Substitution you specify a special symbol in the input

file that identifies the location where changes are to be made. When you run your job, you specify a

replacement symbol value that replaces the special symbol in your input file, but only for that job. You

can then make several runs, each with a different value, without having to make any additional

modifications to the input file.

For more information, please see Symbolic Substitution (App. A) in the MSC Nastran Installation and

Operations Guide.

3CHAPTER 1

Overview of MSC Nastran 2008 r1

List of Errors Resolved

The list of errors resolved in this release can be found at:

http://www.mscsoftware.com/support/prod_support/nastran/errorlist/files/error2008.lst

List of Example Problems for the MSC Nastran 2008 r1 Release

The table below is a list of the example problems in this release guide and the associated file name that

can be found in the test problem library, or in the documentation directory in your MSC Nastran 2008 r1

installation.

List of MSC Nastran Documents Released with MSC Nastran 2008 r1

Along with this Release Guide, the following documents are updated for the MSC Nastran 2008 r1

release:

• MSC Nastran Installation and Operations Guide

• MSC Nastran Quick Reference Guide

Example Problems File Name

Three-bar Truss page 59 tomex1.dat

A Square page 69 togex1.dat

Fluid Modes as Design Constraints page 79 d200fmd1.dat


Overview4

Chapter 2: Implicit Nonlinear MSC Nastran 2008 r1 Nastran Release Guide

2 Implicit Nonlinear

� Implicit Nonlinear - SOL 600


Implicit Nonlinear - SOL 6006


The following is a discussion of the new additions and improvements made for MSC Nastran 2008 r1.

Support of Large Grid and Element IDs

The largest addition to SOL 600 for MSC Nastran 2008 r1 is the addition of a capability to support very

large grid and element IDs. Up to 10-digit IDs may now be used for grids and elements when SOL 600

is used, however to be compatible with other solution sequences, IDs should not normally exceed a value

of 99999999. Large IDs may be specified separately for grids, elements, or both items. Large ID

capability is not the default for MSC Nastran 2008 r1 and, if it is needed for a particular model, it must

be activated by placing one of the following items shown in bold on the SOL 600,ID, 155 in the MSC

Nastran Quick Reference Guide (most other items are omitted to prevent confusion):

SOL 600,SID MRENUMBR= MRENUELE= MRENUGRD=

Please see parameters, MRENUMBR, 786, MRENUELE, 784, and MRENUGRD, 785 in the MSC Nastran

Quick Reference Guide. These key words are only required if the number of digits is greater than seven.

Multiple RFORCE Entries in the Same Subcase

SOL 600 now supports multiple RFORCE entries in the same subcase so that different portions of the

structure can rotate with different angular velocities, or even in different directions. To accomplish this,

the two or more RFORCE entries should have the same SID (see below) and field 4 of the each

continuation entry should specify IDRF which points to a SET 3 entry designating which elements apply

to that particular RFORCE entry.

RFORCE (addition to the RFORCE entry for SOL 600)

Format:

BCONTACT Case Control Command Clarification

Normally, only one form of this entry may be used in any given analysis. The exception, for SOL 600

only, is that BCONTACT=NONE may now be used for any subcase desired and/or for increment zero

1 2 3 4 5 6 7 8 9 10

RFORCE SID G CID A R1 R2 R3 METHOD

RACC MB IDRF

IDRF (SOL 600

only)

ID indicating to which portion of the structure this particular RFORCE entry applies.

It is possible to have multiple RFORCE entries in the same subcase for SOL 600 to

represent different portions of the structure with different rotational velocities. IDRF

corresponds to a SET3 entry specifying the elements with this acceleration.

7CHAPTER 2

Implicit Nonlinear

and some other form such as BCONTACT=N used for the other subcases. This allows some subcases to

have contact and others to have no contact. Analysis restarts must use the same form as the original run

BCONTACT=ALLxxx cannot be mixed with

BCONTACT=NONE or BCONTACT=N in the same input file.

BCTABLE Bulk Data Entry Additions

Several new fields have been made in the BCTABLE entry to clarify which shell surfaces may contact

for SOLs 101 and 600. The new fields are shown in bold:

Format:

For detailed descriptions on the new fields and Remarks 22 and 23 see BCTABLE (SOL 600), 1114 in the

MSC Nastran Quick Reference Guide.

Other BCTABLE Clarifications

If the user leaves IDSLAVE and IDMAST blank, then NGROUP is normally required and continuation

entries are usually expected for NGROUP SLAVE/MASTER combinations. Exceptions are (a) for

SOL 700 where self-contact may be designated using a slave IDSLA1 of zero and no MASTER entry

and (b) for SOL 600 if no contact is desired in increment zero or a particular subcase, fields 1 and 2 of

the primary BCTABLE entry for that subcase is entered, all other fields left blank and no continuation

1 2 3 4 5 6 7 8 9 10

BCTABLE ID IDSLAVE IDMAST NGROUP COPTS COPTM

“SLAVE” IDSLA1 ERROR FNTOL FRIC CINTERF IGLUE

ISEARCH ICOORD JGLUE TOLID DQNEAR DISTID

FBSH FRLIM BIAS SLIDE HARDS COPTS1 COPTM1

BKGL BGST BGSN BGM BGN

HHHB HCT HCV HNC BNC EMISS HBL

FK EXP METHOD ADAPT THICK THICKOF PENV

FACT TSTART TEND MAXPAR PENCHK FSF VSF

EROSOP IADJ SOFT DEPTH BSORT FRCFRQ SNLOG

ISYM I2D3D IGNORE SPR MRP VDC SBOPT

SFS SFM SST MST SFST SFMT AUTO

LCID FCM US PSF FA ED INTTYPE

NFLS SFLS IGNOFF FSLIM PYS TDIC CDIST

NFLF SFLF NEN MES TBLCID TBLAB IGAP

FTBID VC SMOOTH FLANGL PENMAX THKOPT SHLTHK

SLDTHK SLDSTF

DBID TIDRF TIDNF DBDTH DFSCL NUMINT

“MASTERS” IDMA1 IDMA2 IDMA3 IDMA4 IDMA5 IDMA6 IDMA7

IDMA8 IDMA9 ...



lines are entered. The SOL 600 no contact condition may be achieved in either of two ways - set Case

Control BCONTACT=ID and enter a matching BCTABLE with that ID in field 2 and all other fields

blank or set BCONTACT=NONE and do not enter BCTABLE for that subcase.

New Triangular Plane Stress Element

The MRALIAS parameter or the ALIASM option may be used to specify that a 3-node plane stress

element is to be used by specifying type 201.

New Solid Shell Element

A new solid shell element (CSSHL) has been added to SOL 600. The solid shell is normally used for

contact problems where contact occurs on both the top and bottom faces. This element may be used with

either homogeneous properties or by referencing a PCOMP or PCOMPG.

CSSHL (SOL 600)

Defines the connection for a Solid Shell with 6 or 8 grid points.

Format:

Examples:

1 2 3 4 5 6 7 8 9 10

CSSHL EID PID G1 G2 G3 G4 G5 G6

G7 G8

CSSHL 44 11 1 2 3 4 5 6 quad

7 8 quad

CSSHL 51 22 11 12 13 21 22 tria

23 tria

CSSHL 51 22 11 12 13 13 21 22 tria

23 23 tria

Note: The second and third examples are equivalent to each other.

Field Contents

EID Element identification number. (1 < Integer < 1E11, Required)

9CHAPTER 2

Implicit Nonlinear

See CSSHL (SOL 600) (p. 1342) in the MSC Nastran Quick Reference Guide for additional details. An

example is tpl model hextqb-sshl2.dat

PSSHL (SOL 600)

Defines the properties for Solid Shell (CSSHL) elements.

Format:

Example:

New Penta 15 Solid Element

Support for Penta 15 elements with mid-side nodes has been available in previous releases but they were

formed using hexa 20 elements with a collapsed side. This formulation is not as accurate as the new true

penta 15 formulation. The old collapsed side formulation is no longer used starting with this release and

the new formulation is used automatically. There are no changes to the input data required.

PID Property identification of a PSHELL, PCOMP, or PCOMPG entry. (Integer > 0,

Required). Note that the MID2 entry on the PSHELL or PCOMP is ignored.

Gi Grid point identification number of connection points. (Integer or blank, for quad

shapes all eight values are required, for triangle shapes only G4 and G8 may be left

blank in which case G4=G3 and G8=G7.)

1 2 3 4 5 6 7 8 9 10

PSSHL PID MID IT SF

PSSHL 11 33 .8333

Field Contents

PID Property identification number. (Integer > 0, Required)

MID Identification of a MAT1xxx entry. All MAT entries available in SOL 600 can be

specified except for hyperelaastic materials. (Integer > 0)

IT Transition thickness - Enter only if a solid shell is attached to a standard shell (such

as CQUAD4), in which case TT is the thickness of the standard shell. (Real, Default

= 0.0)

SF Transverse shear factor - Leave blank if transverse shear is not to be considered.

(Real or blank, if entered SF must range between 0.0 and 1.0)

Field Contents



MARCOUT – t16 Output Results Changes

All output quantities supported by Marc are available in the SOL 600 t16 file and may be specified using

the MARCOUT Bulk Data entry. Additions for this release are as follows:

Please note that for SOL 600, MSC Nastran Case Control commands such as SET ID=, DISP=,

STRESS=, STRAIN= only control the output in the .op2, .xdb, punch, .f06 and/or jid.marc.out file(s).

The Case Control requests do not affect the. t16 output.

Limiting t16 Output to Selected Elements or Grids

For large nonlinear models the output can become very large. Sometimes only a certain portion of the

structure is of concern. The following new entry may be used in SOL 600 to specify which elements or

nodes should be output. The default is all elements and nodes will be output if the entry is not made. This

entry may be used in combination with MARCOUT or the default MARCOUTs may be used.

MT16SEL – Limits elements and/or grid results to selected elements or grids for t16 and t19 file results

Format

E-USER 1st user-defined element post code(s) are generated by user subroutine plotv.f

E-USER1 2nd user-defined element post code(s)

E-USER2 3rd user-defined element post code(s)

E-USER3 4th user-defined element post code(s)

E-USER99 100th user-defined element post code(s)

These outputs are only available in the .t16 file, not in .op2, .xdb, .f06, punch. A

maximum number of 100 user-defined element post codes may be entered for SOL 600.

N-USER 1st user-defined nodal post code are generated by user subroutine upstnd.f

N-USER1 2nd user-defined nodal post code are generated by user subroutine upstnd.f

N-USER2 3rd user-defined nodal post code are generated by user subroutine upstnd.f

N-USER3 4th user-defined nodal post code are generated by user subroutine upstnd.f

N-USER4 5th user-defined nodal post code are generated by user subroutine upstnd.f

N-USER99 100th user-defined nodal post code are generated by user subroutine upstnd.f, etc.

User-defined outputs are only available in the .t16 file, not in .op2, .xdb, .f06, punch. A

maximum of 100 user-defined nodal post codes may be entered for SOL 600.

1 2 3 4 5 6 7 8 9 10

MT16SEL TYPE ID1 THRU ID2 BY ID3

11CHAPTER 2

Implicit Nonlinear

Example:

See MT16SEL (SOL 600), 1851 in the MSC Nastran Quick Reference Guide for more details.

Analytical Contact Threshold Angle

Starting with this release it is possible to define analytical contact threshold angles for different subcases.

To do so, include the following entry:

Defines automatic analytical contact threshold angle for multiple subcases - SOL 600 only.

Format:

Example:

Please see SANGLE (SOL 600), 2202 in the MSC Nastran Quick Reference Guide for more details. An

example using SANGLE is TPL model sangle1a.dat.

Additions to NLSTRAT

The following additions have been made to the NLSTRAT entry to support heat transfer analyses which

was introduced in the previous release.

MT16SEL GRID 1 THRU 100 BY 5

ELEM 100 THRU 500 BY 2

1 2 3 4 5 6 7 8 9 10

SANGLE IDC IDB Angle IDC IDB Angle

SANGLE 1 4 50.0 1 6

2 4 -1.0 2 6 55.0

Field Contents

IDC Identification number of a SUBCASE Case Control command. (Integer, no Default) To

enter a value corresponding to Marc’s increment zero, set IDC=0.

IDB Identification of a contact body (must be the same as a BCBODY ID) (Integer,

no Default)

Angle Threshold automatic analytical contact angle (SANGLE). (Real, Default = 60.0)

A value of -1.0 turns off analytical

PLANKS Planks second constant (Real, Default=14387.69 microMK) PARAMETERS (4,6)

CLIGHT Speed of light in a vacuum (Real, Default=2.9979E14 micor M/s) PARAMETERS

(4,7)

RAPMAX Maximum change in the incremental displacement in a Newton-Raphson iteration

(Real, Default = 1.0E30) PARAMETERS (4,8)



Generalized Alpha Dynamic Integration Method

For previous releases, several numerical integration methods were available for dynamic analysis. One

additional method, called the Generalized Alpha or Hilber-Hughes Taylor Method has been added. This

method is sometimes superior to the others for difficult dynamics problems, particularly those involving

contact. The single step Houbolt method is still the default for this release, but the new method may

become the default in subsequence releases. To select any of these methods, enter the following bulk

data parameter:

MHOUBOLT

Integer, Default = 0, MSC Nastran Implicit Nonlinear (SOL 600) only.

If MHOUBOLT=0, SOL 600 transient dynamics will use the single step Houbolt numerical

integration method.

MHOUBOLT=1, SOL 600 transient dynamics will use the Newmark Beta numerical integration method.

MHOUBOLT=2, SOL 600 transient dynamics will use the standard multi-step Houbolt numerical

integration method.

MHOUBOLT=7, SOL 600 transient dynamics will use the generalized alpha (Hilber-Hughes Taylor)

numerical integration method.

MATVP Material Property Entry

The MATVP entry has completely changed so that both SOL 400 and 600 may use the same entry. Please

refer to MATVE (SOL 600), 1775 in the MSC Nastran Quick Reference Guide for the new description and

be sure to update any existing input files that have an older entry and need to be run with this release. An

example is TPL model vcreep.dat.

MATSMA Shape Memory Alloy Material Property Entry

A new shape memory allow material property entry is now available for use both in SOL 400 and 600.

Please see MATSMA (SOL 600), 1742 in the MSC Nastran Quick Reference Guide for a full description

of this entry.

FISTIF Initial friction stiffness for model 6 used in first cycle of an increment to define the

friction stiffness matrix in cases where a touching node has a zero normal force and

the amount of sliding does not exceed the elastic sticking limit (Real, Default = 0.0 in

which case the program calculates it) PARAMETERS (5,1)

SNGMIN Minimum value that indicates a singularity if a direct solver is used (Real, Default =

0.0 in which case the value is set internally by the program) PARAMETERS (5,2)

RTMAX Maximum change in temperature per iteration in radiation simulations (Real, Default

= 10 times the maximum error in temperature estimate or 100.0) PARAMETERS (5,3)

13CHAPTER 2

Implicit Nonlinear

Nonlinear Elastic Orthotropic Materials

An orthotropic material model that allows the user to enter the nine material parameters as a function of

strain and temperature is now available. This is defined through the MATNLE6 and TABLE3Di options.

Composite Integration Methods to Reduce Computer Time

SOL 600 allows composite materials to be fully nonlinear. The properties of each layer may have

plasticity and/or have properties that vary with temperature. Often analyses are conducted where the

material properties are assumed to remain linear and are at a constant temperature. For such cases,

computer time can be reduced by significant amounts by taking these factors into account. A new entry,

PCOMPF, is available to specify which elements can use the faster integration methods. This entry is

shown below and an example is compos1-fast3.dat in the tpl directory.

Format:

Alternate Formats:

1 2 3 4 5 6 7 8 9 10

PCOMPF INT PID1 THRU PID2 BY N

1 2 3 4 5 6 7 8 9 10

PCOMPF INT PID PID PID1 THRU PID2 PID3 THRU

PID4 PID5 TO PID6 PID PID PID PID7

THRU PID8 BY N

1 2 3 4 5 6 7 8 9 10

PCOMPF INT ALL

Field Contents

PID1 Property identification number. (0 < Integer < 10000000) corresponds to a matching

PCOMP or PCOMPG entry.

INT INT=1, (Default), conventional through the thickness integration of each layer, allows

all available material behavior through the thickness.

INT=2, linear elastic material, fast-integrated through the thickness - thermal strains

and temperature dependent material properties are not allowed.

INT=3, linear elastic material, fast integrated through the thickness, temperature

dependent elasticity, and thermal strains are allowed.



New SOL 600 Bulk Data Entries and Parameters

Table 2-1 contains new Bulk Data entries for SOL 600 in MSC Nastran 2008 r1. More details can be

found in the MSC Nastran Quick Reference Guide.

Table 2-2 contains new Parameters for SOL 600 in MSC Nastran 2008 r1. More details can be found in

the MSC Nastran Quick Reference Guide.

Table 2-1 New Bulk Data Entries for SOL 600

New for MSC Nastran 2008 r1 (SOL 600)

Bulk Data Entries Description

CSSHL Defines the connection for a solid shell with 6 or 8 grid points.

MATSMA Material properties for shape memory alloys (SOLs 400 and 600 only)

MATNLE6 Properties for nonlinear orthotropic elastic material

MT16SEL Limits elements and/or grid results to selected elements or grids for t16

and t19 file results

PSSHL Defines the properties for solid shell (CSSHL) elements.

SANGLE Defines automatic analytical contact threshold angle for multiple

subcases.

Table 2-2 New Parameters for SOL 600


Parameters Description

MARCMATT (Integer) Determines if Marc input file will be created with materials using the

table-driven formats or not (Default = -1 if parameter is not entered)

MARROUTT Determines whether an inconsistent set of outputs between the Marc t16 file

(selected using MARCOUT) and standard Nastran output selected using Case

Control requests (and param,post) is allowed or not (Default = -1 if parameter is

not entered)

MBENDCAP Determines how PBEND internal pressure will be treated for SOL 600, (Default

= 1 if this parameter is not entered).

MDAREAMD Option to modify or not modify all DAREA entries which are not associated with

any other loads (DAREA entries that supply the actual load)

MFORCOR1 Option to correct forces entered twice (at the same node) in multiple subcases.

MINVASHF Inverse power “auto sift” value.

MINVCITR Inverse power method, number of iterations.

MINVCSHF Inverse power shift frequency in Hz.

15CHAPTER 2

Implicit Nonlinear

MINVCTOL Inverse power convergence tolerance.

MINVFMAX Inverse power max frequency to extract in Hz.

MINVNMOD Inverse power max number of modes to extract.

MRENUELE It is best if MRENUELE is specified in the SOL entry. Some models will not have

memory allocated properly if this parameter is placed in the bulk data.

(Integer) Determines if SOL 600 elements will be renumbered or not (Default = -1

if parameter is not entered and MRENUELE is not entered on the SOL 600 entry)

MRENUGRD It is best if MRENUGRD is specified in the SOL entry. Some models will not

have memory allocated properly if this parameter is placed in the bulk data.

(Integer) Determines if SOL 600 grid id’s will be renumbered or not (Default = -1

if parameter is not entered and MRENUGRD is not entered on the SOL 600

entry)

MRENUMBR Determines if both grid and element IDs for SOL 600 will be renumbered or not.

MRPELAST Determines whether PELAST will be skipped or cause the job to abort for

SOL 600, (default = -1 if parameter is not entered). SOL 600 does not support

PELAST. PBUSHT along with CBUSH and PBUSH should be used instead.

MRPREFER Determines to output SOL 600 stresses on the t16 file in the standard Marc

coordinate system for the element or the “preferred” (layer) coordinate system

when the model contains composite elements.

MSPEEDCB Determines whether CBEAM increased speed options are to be applied. This

option may be necessary for models with a large number of beams whose element

ID’s are large.

MTABLD1M Option to modify or not to modify all TABLED1 entries which do not start with

the first point of (0.0, 0.0)

MTABLD1T Specifies the second time value of all TABLED1 entries that do not start with the

first point being (0.0, 0.0) if PARAM,MTABLD1M=1.

MULRFORC Option to activate multiple RFORCE entries for different portions of the model in

the same subcase.

Table 2-2 New Parameters for SOL 600


Parameters Description

Chapter 3: NVH and Acoustics MSC Nastran 2008 r1 Release Guide

3 NVH and Acoustics

� NVH Enhancements


NVH Enhancements18

NVH Enhancements

ACMS with Acoustic External Superelement Creation

The ACMS feature (see the DOMAINSOLVER ACMS (PARTOPT=DOF) Executive Control statement

in the MSC Nastran Quick Reference Guide) is now fully integrated with the creation of an external

acoustic superelement which contains both the fluid cavity and the fluid-structural boundary. External

superelement creation is requested with the EXTSEOUT Case Control command. For an acoustic

external superelement, the component modes and their associated reduced stiffness, mass, etc. matrices

are computed separately for the fluid and structure. If QSETi and SPOINT Bulk Data entries are used

to define the generalized coordinates then there must be a sufficient number to accommodate both the

fluid and structure modes. If there are insufficient generalized coordinates then the program will truncate

both the fluid and structural modes proportionally. It is for this reason that PARAM,AUTOQSET,YES is

strongly recommended to avoid potential modal truncation. Fluid points may also be specified on the

boundary of the superelement using the ASETi entry. However, free-fixed or free-free fluid or structure

boundaries are not permitted with ACMS.

Multiple RANDOM Looping

Prior to this release, only one set of RANDPS Bulk Data entries could be selected per run. In other

words, the RANDOM Case Control command could only reference a single RANDPS set identification

number (SID). In this version multiple SIDs may be specified on the SET command if its identification

number is in turn referenced on a RANDOM command. For example;

SET 1000 = 101 103 107 110RANDOM = 1000

where 101, 103, 107, and 110 refer to multiple RANDPS SIDs. It should be noted for this type of usage

the SET id must be unique with respect to all RANDPS SIDs; e.g., 1000 is not an SID on any RANDPS

entry.

Sparse OUTPUT4 Format for External Superelement Creation

The sparse OUTPUT4 format option is now used for EXTSEOUT (MATRIXOP4=unit) Case Control

command. This will result in significant disk space reduction of the resulting op4 file.

Binary op2 and op4 Compatibility Robustness

Starting in version V2004 r3, binary op2 and op4 files could be read across dissimilar platforms.

However, several errors were encountered since V2004 r3 and are now corrected in MSC Nastran 2008

r1.

19CHAPTER 3

NVH and Acoustics

Merged Superelement Results

PARAM, FULLSEDR, YES may be specified in a superelement analysis to merge several types of

results (displacements, stresses, etc.) across all superelements into a single non-superelement results

format. FULLSEDR is intended for superelement models which contain unique IDs across all element

and grid points. FULLSEDR benefits third party post-processing programs which have difficulty

digesting superelement results in the op2 or .pch files.


NVH Enhancements20

Chapter 4: Numerical Methods and High Performance Computing MSC Nastran 2008 r1 Release

Guide

=

4 Numerical Methods and High

Performance Computing

� Factor Matrix Caching for Lanczos

� New TAUCS Indefinite Solver Improves Lanczos Performance

� Shared Memory Parallel (SMP) Scalability Improvements for Static

Analysis

� New MAXRATIO Information Output

� New SPARSESOLVER MDTSTATS Information Output


Factor Matrix Caching for Lanczos22

Factor Matrix Caching for Lanczos

Introduction

In solution sequences where many linear systems are solved using the same coefficient matrix, the FBS

time can be significant when the factor matrix is stored out of core. Examples include dynamic solution

sequences which use the Lanczos method and nonlinear transient response. In MSC Nastran 2008 r1,

new logic has been introduced to cache as much of the factor as possible in memory.

Benefits

The reduced I/O can cut the elapsed time for FBS by five to 30 percent, depending on the size of the factor

matrix, the number of right-hand sides, and the amount of memory available.

Method and Theory

The underlying method has not changed; only the memory usage. Previously, only the minimum amount

of factor data needed to perform the FBS was read from the factor data block each time and FBS was

required. Now, as much of the factor as possible is cached in memory between FBS calls, reducing the

I/O required.

Inputs

For Lanczos, no input is required, except when running on Linux IA64. This option has not been

beneficial on Linux IA64, but it can be turned-on setting SYSTEM cell 146 to -1. For nonlinear transient

analysis, the factor caching logic must be activated by setting SYSTEM(146) to -1. For comparison

purposes, the factor-caching logic can be deactivated by setting SYSTEM(146)=+1.

Outputs

A new System Information Message 4157 will appear in the. f04 file:

In addition, when SYSTEM cell 166 to 2, additional time stamps “FBSI BGN” and “FBSI END” appear

in the .f04 file.

MEMORY REQUIREMENTS FOR IN-CORE FACTOR OPTION: AVAILABLE MEMORY: 229909 KWORDS NUMBER OF TOTAL FRONTS: 42935 NUMBER OF FRONTS WHICH FIT IN CORE: 14225 EST MEMORY FOR ENTIRE FACTOR TO IN CORE: 586268 KWORDS

23CHAPTER 4

Numerical Methods and High Performance Computing

Guidelines and Limitations

It is difficult to estimate the amount of memory to specify for a given model so that most of the factor

can be cached. The “estimate” program can give a starting point. A rule of thumb would be to give 3

times the amount of memory recommended in the “estimate” output, but no more than 75% of the

physical memory available on the machine.

Demonstration Examples

Example 1:

The following example is a powertrain model with 160,000 grids and 940,000 degrees of freedom.

Twenty mode shapes are required using Lanczos. A total of 14 FBS operations are performed. The job

is run on workstation with two dual-core 64-bit Pentium Xeon processors running at 3GHz, 8GB of

physical memory. The job is submitted with mem=6gb. By caching the factor, the total FBS time is

reduced by 30%, resulting in a 13% reduction in the overall READ time.

Lanczos Performance Improvement

0

50

100

150

200

250

300

350

FBS time

[seconds]

READ time

[seconds]

CP

U s

eco

nd

s

Factor out of core

Factor Cached


New TAUCS Indefinite Solver Improves Lanczos Performance24

New TAUCS Indefinite Solver Improves Lanczos Performance

Introduction

A new symmetric indefinite factorization method from the TAUCS software project

www.tau.ac.il/~stoledo/taucs/ has been integrated into MSC Nastran 2008 r1. It is available in the

DCMP, DECOMP, SOLVE, RMG2, SDR2, and READ modules, with the main focus on the READ

module. The new solver keeps all data in memory.

Benefits

The new method can significantly improve the factorization and FBS time, particularly in the Lanczos

procedure, for problems which fit in memory. In this release, the method is only recommended on the

Linux x86_64 platforms (Intel EM64T and AMD Opteron).

Method and Theory

The new method is based on a hybrid left-looking /supernodal multifrontal technique, with emphasis on

data locality.

Inputs

The new method can be selected by setting SYSTEM cell 166 to 16384.

Outputs

The following information is printed in the .f04 file.


In this release, this method has only been tuned for the Linux x86_64 platform (Intel EM64T/AMD

Opteron) and is only recommended for that platform. This method must keep all data in memory, so it

is recommended that it be submitted with 75% of the physical memory available.

Elimination tree depth is 7043 Symbolic Analysis of LDL^T: 1.53e+08 nonzeros, 9.48e+10 flops, 1.40e+09 bytes in L Relaxed Analysis of LDL^T: 1.80e+08 nonzeros, 1.14e+11 flops, 1.72e+09 bytes in L Symbolic Analysis = 3.415 seconds (3.411 cpu)12:07:41 1:05 15753.0 24.0 61.1 6.5 TAUD END12:07:47 1:11 16890.0 1137.0 66.7 5.5 TAUD BGN Using blocked update in dense factorization. Supernodal Left-Looking LDL^T = 49.121 seconds (48.390 cpu) Post Analysis of LDL^T: 1.80e+08 nonzeros, 1.14e+11 flops, 1.72e+09 bytes in L

www.tau.ac.il/~stoledo/taucs/%20

25CHAPTER 4



A normal modes computation has been performed using the default factorization method (SPDC) and

the new TAUCS method on the following models. The jobs are run on a workstation with two dual-core

64-bit Pentium Xeon processors running at 3GHz, 8GB of physical memory. Each job was submitted

with mem=6gb.

Model Grids DOF Modes Factorizations FBS’s

Powertrain 160,000 940,000 20 2 14

Rotor 197,000 592,000 8 2 8

Viga 139,000 413,000 5 2 5

Van 103,000 584,000 73 2 43

Lanczos Performance

0

200

400

600

800

1000

1200

1400

Rotor viga Powertrain van

Model

RE

AD

tim

e [

cp

u s

eco

nd

s]

SPDC

TAUCS


Shared Memory Parallel (SMP) Scalability Improvements for Static Analysis26

Shared Memory Parallel (SMP) Scalability Improvements for Static Analysis

Introduction

In solution sequences where a linear system must be solved with a large number of right-hand sides,

several passes over the factor matrix may be needed to compute all of the solution vectors. This

performance enhancements keeps as much of the factor matrix as possible in memory to reduce the I/O,

improve overall performance, particularly SMP performance.

Benefits

The performance of any large FBS with many right-hand sides will be improved by as much as 30%. For

example, superelement models with static (Guyan) reduction, statics models with many load cases, and

heat transfer models with radiation will benefit from this enhancement.

Method and Theory

The underlying method has not changed; only the memory usage. Previously, only the minimum amount

of factor data need to perform the FBS was read from the factor data block during each FBS pass. Now,

as much of the factor as possible is cached in memory between FBS passes, reducing the I/O required.

Inputs

The feature is automatically activated on all platforms except Linux IA64 when enough memory is

available to store at least 32 right-hand side vectors, and when the factor and right-hand side have the

same data type (both real or both complex). The minimum number of right-hand sides required to

activate the feature can be overridden with the value of SYSTEM cell 70.

Outputs

A system information message is printed in the .f04 file if any part of the factor is cached:

Guidance and Limitations1. This feature is not available on the Linux IA64 platform.

*** SYSTEM INFORMATION MESSAGE 4157 (PREFAC1) A PORTION OF THE SPARSE FACTOR HAS BEEN CACHED IN MEMORY FOR THE FBS. 34435 FRONTAL MATRICES OUT OF A TOTAL OF 37881 ARE STORED IN MEMORY. MEMORY AVAILABLE: 412 M WORDS ESTIMATED ADDITIONAL MEMORY NEEDED TO STORE THE ENTIRE FACTOR: 281 M WORDS

27CHAPTER 4


2. This feature requires additional memory. The recommended amount is three times the amount

specified by the “estimate” program plus enough to hold 32 right-hand side vectors.


The following example is a linear statics model of a car body with 42,000 grid points, 246,000 degrees

of freedom, and 8,300 load cases. The job was run on an IBM pSeries workstation with 8 1.9GHz

power5 processors, and 8GB of physical memory.

Linear Static Performance

0

100

200

300

400

500

600

700

800

900

1000

Serial SMP=2 SMP=4

Ela

psed

Tim

e [

Seco

nd

s]

R2

R3(Factor Cached)


New MAXRATIO Information Output28

New MAXRATIO Information Output

Introduction

A new interface is now available for analysts to better control the generation of matrix diagonal term ratio

statistics produced by the sparse symmetric matrix decomposition process in the DCMP module. The

matrix diagonal term ratio statistics are sometimes useful in determining the quality of the matrix

decomposition process. In general, for linear static analysis, high or negative ratios indicate a loss of

accuracy and could be indicative of a modeling error. The MAXRATIO functionality was a pre-release

capability in the MSC Nastran 2007 r1 release. For MSC Nastran 2008 r1 this is now a production

capability.

Benefits

The new interface provides analysts with more control over the process than the existing method of

supplying a value for the MAXRATIO DMAP parameter. In addition, a new output data option is

available in the form of a simple bar chart that provides a more comprehensive view of the ratio data.

Method and Theory

No new theory is involved. The method simply involves the computation of a ratio defined as the original

matrix diagonal term divided by the decomposed matrix diagonal term. These ratios are placed in a table

together with the external identifier associated with the row/column of the term. This table is then

processed according to the options requested by the user.

Inputs

The matrix diagonal term ratio output options are controlled by keywords specified on the

SPARSESOLVER Executive Control statement. See New SPARSESOLVER MDTSTATS Information

Output, 32 for a complete description of this statement.

Outputs

The matrix diagonal term ratios can be presented in two different views. The first view is the table view,

in which each ratio is listed together with the external identifier of the row/column of the matrix, as well

as the original input matrix diagonal term. This format is virtually identical to that produced by the

previous version when any ratio exceeds the value of the MAXRATIO input parameter.

The second view of the ratios is statistical in nature. It is similar to a bar chart. A series of bar segments

are generated. There are two options for specifying the segment widths of the bars. The default option

uses powers of 10 as the widths (e.g., 10.0 to 100.0, and 100.0 to 1000.0). The second option allows the

user to specify how many segments are desired. The program will compute the segment width using the

29CHAPTER 4


maximum and minimum ratios. For each bar in the chart, the total number of terms in the range is

tabulated together with a visual indication of the percentage number of terms in that particular bar.

Note that when negative matrix diagonal term ratios are detected, they will always be output if the

TABLE option is specified.

These new views of the ratios do not replace any existing diagnostics generated by the DCMP module if

a problem is detected. Under these conditions, output from the table view may duplicate previous output

generated by DCMP module error processing.


The matrix diagonal term ratio statistics are sometimes useful in determining the quality of the matrix

decomposition process. In general, high ratios indicate a loss of accuracy. The feature can be used by

taking all of the program defaults for the various control variables. These defaults produce both the table

and bar outputs. The table is limited to 25 ratios that exceed 1.0E+05. The bar chart uses powers of ten

for segment widths. This can be done by adding

SPARSESOLVER DCMP (MDTRATIO)

to the Executive Control Section of the input data file.

The use of this new feature is currently limited to sparse symmetric matrix operations in the DCMP

module.

If there are scalar-type points present in the problem, the degrees of freedom associated with these points

will be grouped into the results for the translational degrees of freedom output.

Demonstration Example

A simple example is presented that demonstrates the use of some of the new features available for output

of the matrix diagonal term ratios. The SPARSESOLVER Executive Control statement is used to specify

the desired features. The example is for demonstration purposes only, and is not representative any

particular modeling situation. The model data consists of a simple plate structure subject to an end load.

Example Input Data$$ Example problem to demonstrate matrix diagonal term ratios$id test,casesol 101SPARSESOLVER DCMP (MDTRATIO) cendspc=100load=1000disp=allbegin bulkgrdset,,,,,,,6cquad4,101,101,1,2,52,51


New MAXRATIO Information Output30

cquad4,102,101,2,3,53,52cquad4,103,101,3,4,54,53cquad4,104,101,4,5,55,54cquad4,105,101,5,6,56,55cquad4,106,101,6,7,57,56cquad4,107,101,7,8,58,57cquad4,108,101,8,9,59,58cquad4,109,101,9,10,60,59cquadr,1101,101,1,2,52,51cquadr,1102,101,2,3,53,52cquadr,1103,101,3,4,54,53cquadr,1104,101,4,5,55,54cquadr,1105,101,5,6,56,55cquadr,1106,101,6,7,57,56cquadr,1107,101,7,8,58,57cquadr,1108,101,8,9,59,58cquadr,1109,101,9,10,60,59grid, 1,, 0.0,0.0,0.0grid, 2,, 1.0,0.0,0.0grid, 3,, 2.0,0.0,0.0grid, 4,, 3.0,0.0,0.0grid, 5,, 4.0,0.0,0.0grid, 6,, 5.0,0.0,0.0grid, 7,, 6.0,0.0,0.0grid, 8,, 7.0,0.0,0.0grid, 9,, 8.0,0.0,0.0grid,10,, 9.0,0.0,0.0grid,51,, 0.0,1.0,0.0grid,52,, 2.4,1.0,0.0grid,53,, 3.5,1.0,0.0grid,54,, 4.6,1.0,0.0grid,55,, 5.7,1.0,0.0grid,56,, 6.8,1.0,0.0grid,57,, 7.9,1.0,0.0grid,58,, 9.0,1.0,0.0grid,59,,10.1,1.0,0.0grid,60,,11.2,1.0,0.0$ctria3,201,101,101,102,151ctria3,202,101,102,152,151ctria3,203,101,102,103,152ctria3,204,101,103,153,152ctria3,205,101,103,104,153ctria3,206,101,104,154,153ctria3,207,101,104,105,154ctria3,208,101,105,155,154ctriar,1201,101,101,102,151ctriar,1202,101,102,152,151ctriar,1203,101,102,103,152ctriar,1204,101,103,153,152ctriar,1205,101,103,104,153ctriar,1206,101,104,154,153ctriar,1207,101,104,105,154ctriar,1208,101,105,155,154grid,101,, 0.0,0.0,0.0grid,102,, 1.0,0.0,0.0grid,103,, 2.0,0.0,0.0grid,104,, 3.0,0.0,0.0grid,105,, 4.0,0.0,0.0grid,151,, 0.0,1.0,0.0

31CHAPTER 4


grid,152,, 3.4,1.0,0.0grid,153,, 4.5,1.0,0.0grid,154,, 5.6,1.0,0.0grid,155,, 6.7,1.0,0.0$pshell,101,1,0.05,1mat1,1,10.+6,,0.33spc1,100,123,1,101spc1,100,3,5,55,105,155spc1,100,1,55,155spc1,100,2,1,101force,1000,10,,1000.0,1.0,0.0,0.0force,1000,60,,1000.0,1.0,0.0,0.0force,1000,105,,1000.0,1.0,0.0,0.0force,1000,155,,1000.0,1.0,0.0,0.0enddata

Example Output

The output generated by the example is shown as follows. Notice that there are two separate sections of

output: one for translational degrees of freedom, and one for rotational degrees of freedom. Within each

section, both a bar chart and table of matrix diagonal term ratios are output.

TRANSLATIONAL DOF DIAGONAL TERM RATIO STATISTICS CHART FOLLOWS FOR THE DECOMPOSITION OF MATRIX KLL ------------------------------------------------|--------------------------------------------------------------------------- DIAGONAL TERM RATIO RANGE #TERMS % TOT |MAXIMUM RATIO = 6.90963E+02 MINIMUM RATIO = 1.00000E+00 ------------------------------------------------|--------------------------------------------------------------------------- 1.0000E+00 TO 1.0000E+01 62 79.49 |**************************************************************************> 1.0000E+01 TO 1.0000E+02 12 15.38 |*************** 1.0000E+02 TO 1.0000E+03 4 5.13 |***** 00 MATRIX/FACTOR DIAGONAL TERMS RATIO SUMMARY TABLE FOR TRANSLATIONAL DOF SORTED ON DIAGONAL RATIO GRID POINT ID DEGREE OF FREEDOM MATRIX/FACTOR DIAGONAL RATIO MATRIX DIAGONAL (TOP 1 RATIOS>MAXRAT= 6.90963E+02) 58 T3 6.90963E+02 5.65535E+04 ROTATIONAL DOF DIAGONAL TERM RATIO STATISTICS CHART FOLLOWS FOR THE DECOMPOSITION OF MATRIX KLL ------------------------------------------------|--------------------------------------------------------------------------- DIAGONAL TERM RATIO RANGE #TERMS % TOT |MAXIMUM RATIO = 3.35974E+02 MINIMUM RATIO = 1.00000E+00 ------------------------------------------------|--------------------------------------------------------------------------- 1.0000E+00 TO 1.0000E+01 38 63.33 |*************************************************************** 1.0000E+01 TO 1.0000E+02 18 30.00 |****************************** 1.0000E+02 TO 1.0000E+03 4 6.67 |*******

00 MATRIX/FACTOR DIAGONAL TERMS RATIO SUMMARY TABLE FOR ROTATIONAL DOF SORTED ON DIAGONAL RATIO GRID POINT ID DEGREE OF FREEDOM MATRIX/FACTOR DIAGONAL RATIO MATRIX DIAGONAL (TOP 1 RATIOS>MAXRAT= 3.35974E+02) 58 R2 3.35974E+02 2.14135E+04


New SPARSESOLVER MDTSTATS Information Output32

New SPARSESOLVER MDTSTATS Information Output

Introduction

A new interface is now available to control the generation of matrix diagonal term statistics for the input

matrix to the sparse symmetric matrix decomposition process in the DCMP module. The matrix diagonal

term statistics can be useful in determining the quality of the model in regions that produce unusually

large or small terms. In general, for linear static analysis, model degrees of freedom with small

stiffnesses could indicate areas where loads will produce large displacements. This feature complements

the MDTRATIO option that controls MAXRATIO output described previously. The SPARSESOLVER

MDTSTATS functionality was a pre-release capability in the MSC Nastran 2007 r1 release. For MSC

Nastran 2008 r1 this is now a production capability.

Benefits

The new interface provides another means of identifying potential modeling errors other than monitoring

the MAXRATIO statistics. One of the new output data options is a simple bar chart that provides a more

comprehensive view of the diagonal term data.

Method and Theory

No new theory is involved. The method involves adding the original matrix diagonal term to the ratio

table where the computation of the ratio is defined to be the original matrix diagonal term divided by the

decomposed matrix diagonal term. These terms are placed together in a table with the external identifier

associated with the row/column of the term. This table is then processed according to the options

requested by the user.

Inputs

The matrix diagonal term statistical output options are controlled by keywords specified on the

SPARSESOLVER Executive Control statement. See the MSC Nastran Quick Reference Guide for a

complete description of this statement.

Outputs

The matrix diagonal term statistics can be presented in two different views. The first is the table view in

which each diagonal term is listed together with the external identifier of the row/column of the matrix,

as well as with the Aii/Lii diagonal term ratio. This format is almost identical to that produced now when

any ratio exceeds the value of the MAXRATIO input parameter. The second view of the diagonal terms

is statistical in nature, similar to a bar chart. A series of bar segments is generated. There are two options

for specifying the segment widths of the bars. The default option uses powers of 10 as the widths (e.g.,

10.0 to 100.0, and 100.0 to 1000.0). The second option allows the user to specify how many segments

are desired. The program will compute the segment width using the maximum and minimum diagonal

33CHAPTER 4


terms. For each bar in the chart, the total number of terms in the range is tabulated together with a visual

indication of the percentage number of terms in that particular bar.

These new views of the diagonal terms do not replace any existing diagnostics generated by the DCMP

module if a problem is detected. Under these conditions, output from the table view may duplicate

previous output generated by DCMP module error processing.


The matrix diagonal term statistics are sometimes useful in determining areas of the model that may pose

problems during the decomposition process, or afterwards during the solution of equations that produce

displacements. In general, unusually large or small values could indicate a modeling problem. The

feature can be used by taking all of the program defaults for the various control variables. These defaults

produce both the table and bar outputs. The table is limited to the 25 largest terms that exceed 1.0E+10,

and the 25 smallest terms less than 1.0. The bar chart uses powers of ten for segment widths. This can

be done by adding

SPARSESOLVER DCMP ( MDTSTATS )

to the Executive Control Section of the input data file.

The use of this new feature is currently limited to sparse symmetric matrix operations in the DCMP

module.

If there are scalar-type points present in the problem, the degrees of freedom associated with these points

will be grouped into the results for the translational degrees of freedom output.

Demonstration Example

A simple example is presented that demonstrates the use of some of the new features available for output

of the matrix diagonal term statistics. The SPARSESOLVER Executive Control statement is used to

specify the desired features. The example problem is used for demonstration purposes only, and is not

representative of any particular model. The model data consists of a simple plate structure subject to an

end load. The model properties have been designed to indicate a potential problem in the bending

properties at grid points 4 and/or 54.

Example Input Data$$ Example problem to demonstrate matrix diagonal term statistics$id test,casesol 101$ Note: SPARSOLVER DCMP options must be enclosed in ()$ Note also that MDTSTATS options must also be enclosed in their own ()SPARSESOLVER DCMP ( MDTSTATS = ( CHART, TABLET, NMAXVALT=10, MAXVALT=1.0e+08,



NMINVALT=20, MINVALT=1.0, TABLER, NMINVALR=30, MINVALR=100.0 ) )cendspc=100load=1000disp=allbegin bulkgrdset,,,,,,,6cquad4,101,101,1,2,52,51cquad4,102,101,2,3,53,52cquad4,103,102,3,4,54,53cquad4,104,102,4,5,55,54cquad4,105,101,5,6,56,55cquad4,106,101,6,7,57,56cquad4,107,101,7,8,58,57cquad4,108,101,8,9,59,58cquad4,109,101,9,10,60,59cquadr,1101,101,1,2,52,51cquadr,1102,101,2,3,53,52cquadr,1103,102,3,4,54,53cquadr,1104,102,4,5,55,54cquadr,1105,101,5,6,56,55cquadr,1106,101,6,7,57,56cquadr,1107,101,7,8,58,57cquadr,1108,101,8,9,59,58cquadr,1109,101,9,10,60,59grid, 1,, 0.0,0.0,0.0grid, 2,, 1.0,0.0,0.0grid, 3,, 2.0,0.0,0.0grid, 4,, 3.0,0.0,0.0grid, 5,, 4.0,0.0,0.0grid, 6,, 5.0,0.0,0.0grid, 7,, 6.0,0.0,0.0grid, 8,, 7.0,0.0,0.0grid, 9,, 8.0,0.0,0.0grid,10,, 9.0,0.0,0.0grid,51,, 0.0,1.0,0.0grid,52,, 2.4,1.0,0.0grid,53,, 3.5,1.0,0.0grid,54,, 4.6,1.0,0.0grid,55,, 5.7,1.0,0.0grid,56,, 6.8,1.0,0.0grid,57,, 7.9,1.0,0.0grid,58,, 9.0,1.0,0.0grid,59,,10.1,1.0,0.0grid,60,,11.2,1.0,0.0$ctria3,201,101,101,102,151ctria3,202,101,102,152,151ctria3,203,101,102,103,152ctria3,204,101,103,153,152ctria3,205,101,103,104,153ctria3,206,101,104,154,153ctria3,207,101,104,105,154

35CHAPTER 4


ctria3,208,101,105,155,154ctriar,1201,101,101,102,151ctriar,1202,101,102,152,151ctriar,1203,101,102,103,152ctriar,1204,101,103,153,152ctriar,1205,101,103,104,153ctriar,1206,101,104,154,153ctriar,1207,101,104,105,154ctriar,1208,101,105,155,154grid,101,, 0.0,0.0,0.0grid,102,, 1.0,0.0,0.0grid,103,, 2.0,0.0,0.0grid,104,, 3.0,0.0,0.0grid,105,, 4.0,0.0,0.0grid,151,, 0.0,1.0,0.0grid,152,, 3.4,1.0,0.0grid,153,, 4.5,1.0,0.0grid,154,, 5.6,1.0,0.0grid,155,, 6.7,1.0,0.0$pshell,101,1,0.05,1pshell,102,1,0.05,2mat1,1,10.+6,,0.33mat1,2,10.+1,,0.33spc1,100,123,1,101spc1,100,3,5,55,105,155spc1,100,1,55,155spc1,100,2,1,101force,1000,10,,1000.0,1.0,0.0,0.0force,1000,60,,1000.0,1.0,0.0,0.0force,1000,105,,1000.0,1.0,0.0,0.0force,1000,155,,1000.0,1.0,0.0,0.0enddata

Example Output

The output generated by the example is shown as follows. There are two separate sections of output: one

for translational degrees of freedom and one for rotational. Within each section, both a bar chart and

table of matrix diagonal terms are output.

=============================================================================================================================== TRANSLATIONAL DOF Aii DIAGONAL TERMS STATISTICS CHART FOLLOWS FOR MATRIX KLL Matrix Trace(Aii) = 1.27351E+08 ------------------------------------------------|--------------------------------------------------------------------------- | MAXIMUM VALUE = 5.94121E+06 MINIMUM VALUE = 4.07806E-01 MATRIX DIAGONAL TERM RANGE #TERMS % TOT | GRID ID = 104, DOF = T2 GRID ID = 54, DOF = T3 ------------------------------------------------|--------------------------------------------------------------------------- 1.0000E-01 TO 1.0000E+00 2 2.56 |*** 1.0000E+03 TO 1.0000E+04 2 2.56 |*** 1.0000E+04 TO 1.0000E+05 18 23.08 |*********************** 1.0000E+05 TO 1.0000E+06 6 7.69 |******** 1.0000E+06 TO 1.0000E+07 50 64.10 |**************************************************************** ===============================================================================================================================



0 MATRIX/FACTOR DIAGONAL TERMS SUMMARY TABLE FOR TRANSLATIONAL DOF SORTED ON Aii DIAGONAL GRID POINT ID DEGREE OF FREEDOM Aii TERM Lii TERM Aii/Lii RATIO (TOP 1 VALUES > 5.94121E+06) 104 T2 5.94121E+06 3.57301E+06 1.66280E+00

0 MATRIX/FACTOR DIAGONAL TERMS SUMMARY TABLE FOR TRANSLATIONAL DOF SORTED ON Aii DIAGONAL GRID POINT ID DEGREE OF FREEDOM Aii TERM Lii TERM Aii/Lii RATIO (TOP 2 VALUES < 1.00000E+00) 54 T3 4.07806E-01 4.07806E-01 1.00000E+00 4 T3 4.70350E-01 2.84250E-01 1.65471E+00

=============================================================================================================================== ROTATIONAL DOF Aii DIAGONAL TERMS STATISTICS CHART FOLLOWS FOR MATRIX KLL Matrix Trace(Aii) = 4.52211E+05 ------------------------------------------------|--------------------------------------------------------------------------- | MAXIMUM VALUE = 2.34493E+04 MINIMUM VALUE = 4.71107E-02 MATRIX DIAGONAL TERM RANGE #TERMS % TOT | GRID ID = 9, DOF = R2 GRID ID = 54, DOF = R1 ------------------------------------------------|--------------------------------------------------------------------------- 1.0000E-02 TO 1.0000E-01 2 3.33 |*** 1.0000E-01 TO 1.0000E+00 2 3.33 |*** 1.0000E+02 TO 1.0000E+03 3 5.00 |***** 1.0000E+03 TO 1.0000E+04 36 60.00 |************************************************************ 1.0000E+04 TO 1.0000E+05 17 28.33 |**************************** ===============================================================================================================================

0 MATRIX/FACTOR DIAGONAL TERMS SUMMARY TABLE FOR ROTATIONAL DOF SORTED ON Aii DIAGONAL GRID POINT ID DEGREE OF FREEDOM Aii TERM Lii TERM Aii/Lii RATIO (TOP 1 VALUES > 2.34493E+04) 9 R2 2.34493E+04 4.87230E+03 4.81277E+00

0 MATRIX/FACTOR DIAGONAL TERMS SUMMARY TABLE FOR ROTATIONAL DOF SORTED ON Aii DIAGONAL GRID POINT ID DEGREE OF FREEDOM Aii TERM Lii TERM Aii/Lii RATIO (TOP 4 VALUES < 1.00000E+02) 54 R1 4.71107E-02 3.08701E-02 1.52610E+00 4 R1 4.71334E-02 9.03202E-03 5.21847E+00 54 R2 1.48139E-01 8.62427E-02 1.71770E+00 4 R2 1.48232E-01 7.96377E-02 1.86133E+00

Chapter 5: Upward Compatibility


=

5 Upward Compatibility

� TEMPERATURE Case Control Command

� Improvements in Fluid Eigenvalue Analysis

� FLUID GRID Points and Partitioning

� Distributed Memory Parallel (DMP) Diagnostic Messages

� System Information Message (SIM) 6916


TEMPERATURE Case Control Command38

TEMPERATURE Case Control Command

According to Remark 8 under the Case Control command TEMPERATURE (Ch. 4) in the MSC Nastran

Quick Reference Guide, TEMPERATURE(INITIAL) and TEMPERATURE(MATERIAL) cannot be

specified in the same run and User Fatal Message 633 will be issued. User Fatal Message 633 is also

issued if TEMPERATURE(BOTH) is specified with TEMPERATURE(INIT) and

TEMPERATURE(MATERIAL). However, in MSC Nastran 2007 r1 and prior, this rule was not enforced

when just TEMPERATURE was specified with TEMPERATURE(INITIAL) or

TEMPERATURE(MATERIAL); and, depending on their relative locations in the Case Control Section,

one of them would be ignored and results will be wrong. For example, the following input file (modified

from TPL problem tempload):

sol 101cendtemp(init) = 10subcase 1 temp = 20 load = 100 spc = 10 disp = allbegin bulkforce,100,3,0,100.0,1.0,0.0,0.0grid, 1,, 0.0,0.0,0.0grid, 2,,10.0,0.0,0.0grid, 3,,20.0,0.0,0.0cbar,1,10,1,2,0.0,0.0,1.0pbar,10,100,1.0,1.0,1.0,1.0mat1,100,1.+4,,0.3,,1.-3rbar,2,2,3,,,,,2.0-4temp,10,1,51.0temp,10,2,52.0temp,10,3,53.0temp,20,1,61.0temp,20,2,62.0temp,20,3,63.0spc1,10,123456,1enddata

produces the following results in versions MSC Nastran 2007 r1 and prior:

In MSC Nastran 2008 r1, this rule is now enforced with TEMPERATURE and UFM 633 will be issued.

To avoid User Fatal Message 633 in MSC Nastran 2008 r1, simply replace TEMPERATURE with

Case Control T1 Displacement at Grid 2 Comment

TEMP(INIT) and TEMP(LOAD) 0.200 Correct answer

TEMP(LOAD) 0.715 Correct answer

TEMP(INIT) and TEMP 0.715 Wrong answer because

TEMP(INIT) is ignored

39CHAPTER 5

Upward Compatibility

TEMPERATURE (LOAD). In MSC Nastran 2009 or later, the BOTH keyword may be removed from

the documentation and the program as an option of the TEMPERATURE command.


Improvements in Fluid Eigenvalue Analysis40

Improvements in Fluid Eigenvalue Analysis1. The elemental mass matrix formulation for the 4-noded CTETRA fluid element has been

modified to prevent spurious modes. Changes may be observed in the fluid’s natural frequencies

especially at the higher frequencies. Use NASTRAN SYSTEM(446)=1 to obtain the previous

version’s formulation.

2. Householder method is automatically selected for the fluid’s system modes if the acoustic cavity

is defined in a superelement and there exist fluid boundary points. The Householder method is

more reliable method when there are fluid points on the boundary of an acoustic superelement.

The switch to Householder occurs if the number of estimated fluid modes is less than or equal to

the value of user PARAMeter FLUIDNE (Default=500).

41CHAPTER 5


FLUID GRID Points and Partitioning

The GP4 module processes displacement set definition Bulk Data entries (e.g. ASET/ASET1). During

this process, it performs various integrity tests on the data supplied by users. One of these tests verifies

that the degree-of-freedom (DOF) components exist for the points specified. The allowable components

depend upon the point type. For instance, a GRID point has six degrees of freedom and one may specify

any (or all) of the components one through six. An SPOINT on the other hand has only a single DOF

and one may specify only a blank or zero as the component. One must also remember that for some types

of analysis, a GRID point may have a reduced number of components available. For example, in

acoustics, one can define GRID points attached to fluid that have only a single component DOF. If the

DOF integrity test fails, Nastran issues message 2049 that informs the user of the problem. The severity

of the message depends upon whether one uses the standard input format (e.g. ASET) or the alternative

format (ASET1) for the Bulk Data entry. When one uses the standard format, one defines each point and

DOF component code explicitly and it must exist. Otherwise, GP4 issues a FATAL 2049 message

indicating that the point is missing. When one uses the alternate entry format, GP4 is prepared for the

possibility that one or more points may not exist in THRU ranges defined on the entry. For this case, a

missing point/DOF produces a WARNING 2049 message.

Consider the following Bulk Data entries:

Since point 1130 is a fluid GRID point, it has only a single DOF associated with it. This DOF is

referenced with DOF component 1. Standard format entry #2 and alternate format entry #4 both use the

proper DOF component code and GP4 places the entries in the a-set without generating any messages.

Standard format entry #3 and alternate format entry #5 on the other hand, contain DOF components that

do not exist for the specified point.

Previous versions handle the processing of entries #3 and #5 as follows:

• For entry #3 (ASET), GP4 issues a FATAL message 2049 indicating that it could not find the

point and the job stops.

• For entry #5 (ASET1), GP4 issues a WARNING message 2049 indicating that it could not find

the point and the job continues, BUT, the point is NOT placed in the a-set as requested.

1. GRID,1130,,0.0,0.0,0.0,-1 $ this is a FLUID GRID point (OCID=-1)

2. ASET,1130,1 $ standard format

3. ASET,1130,123456 $ standard format

4. ASET1,1,1130 $ alternate format

5. ASET1,123456,1130 $ alternate format


FLUID GRID Points and Partitioning42

MSC Nastran 2008 r1 contains a modification to this process for FLUID GRID points and SPOINTs as

follows:

• For entry #3 (ASET), GP4 issues a WARNING message 2049 indicating that certain DOFs are

not available at the point, places the one DOF available at the point in the a-set and continues the

job.

• For entry #5 (ASET1), GP4 issues a WARNING message 2049 indicating that certain DOFs are

not available at the point, places the one DOF available at the point in the a-set and continues the

job

Note the difference between MSC Nastran 2008 r1 and previous versions in this area applies only to

FLUID GRID and SPOINT entries found on displacement set membership (partitioning) definition Bulk

Data entry (ASET, ASET1, OMIT, OMIT1, etc.). Existing bulk data files containing “illegal”

specifications for DOF component codes for FLUID GRIDs and SPOINTs on the partitioning bulk data

entries that ran successfully on previous versions will continue to run, but may produce different results

when run with MSC Nastran 2008 r1 if a DOF becomes a part of the a-set.

43CHAPTER 5


Distributed Memory Parallel (DMP) Diagnostic Messages

Several DMP diagnostic messages used to indicate one or more of the following keywords MDMODES,

GDMODES, FDMODES, MDACMS, GDSTAT, MDSTAT, FDFREQ in the .f06 and f04 files. They

have been replaced by their proper DOMAINSOLVER description, for example, MDMODES was

replaced by “DOMAINSOLVER MODES (PARTOPT=DOF)”.


System Information Message (SIM) 691644

System Information Message (SIM) 6916

SIM 6916 which looks similar to the example below is no longer printed in the .f06 file unless you set

system(294) to a value greater than zero.

*** SYSTEM INFORMATION MESSAGE 6916 (DFMSYM) DECOMP ORDERING METHOD CHOSEN: BEND, ORDERING METHOD USED: BEND

Chapter 6: Optimization MSC Nastran 2008 r1 Release Guide

6 Optimization

� Enhancements in DRESP3

� Topometry Optimization

� Topography (Bead or Stamp) Optimization

� Randomization of an Input Data File

� Random Elimination of Element Types

� Enhancements in SOL 200 Optimization


Enhancements in DRESP346


Introduction

DRESP3 is a feature of SOL 200 in MSC Nastran that allows the user to invoke external software to

calculate design responses that are not available as standard DRESP1 quantities or that cannot be

synthesized using the DRESP2 capability. The DRESP3 is a special purpose capability that requires

some work on the user’s part to function effectively, but it has its adherents who appreciate its ability to

include design responses that are not available from Nastran. Use of this capability has identified three

enhancements for this capability that have been implemented for MSC Nastran 2008 r1:

1. Provision for a capability to provide analytic gradients for the response

2. The ability to produce multiple response outputs from a single DRESP3 call.

3. Reordering of finite difference sensitivities when the DRESP3 has only DRESP1 flags and there

are more DRESP1 responses in the DRESP3 than there are independent design variables in the

model.

Benefits

Analytical gradients provide a performance benefit as well as more robust results than can be expected

from a finite difference approach to obtaining gradients.

The multiple response requirement arises from a typical scenario where a number of design criteria for a

particular component share a common set of inputs. For example, a panel may have criteria on stress,

buckling and fatigue that share parameters for geometry, properties and internal responses. By evaluating

all of these criteria in a single call, duplicate calculations are avoided and the number of calls to the server

are reduced.

The third enhancement above is for the very special application where there are perhaps thousands of

DRESP1 entries and a few hundred design variables. In this case, it makes sense to do the finite

difference gradient calculation by perturbing all the DRESP1 quantities for a particular design variable

and then calling the DRESP3 evaluator. In this way, the number of call to the evaluator is reduced from

2*NRESP1 to 2*NDVI. When NRESP1 >> NDVI, this can provide a major performance improvement

to the extent it enables performing design tasks that were previously out of reach.

User Inputs

The format of the DRESP3 Bulk Data entry is unchanged. The user is required to modify the two server

subroutines that serve to supply Nastran with the information required to evaluate the DRESP3

responses. These two subroutines are R3SGRT and R3SVALD and have the same names as has been

used in previous releases of this capability. They now have additional inputs and outputs as shown here

by examples.

The R3SGRT now not only checks that the DRESP3 Bulk Data entry is supported by the server, but also

identifies the number of responses that are produced from the server and whether analytic or finite

47CHAPTER 6

Optimization

difference gradient techniques will be used during the sensitivity and optimization evaluations.

Listing 6-1 shows an R3SGRT subroutine that utilizes the new features in solving the DRESP3 example

contained in External Response to Include Alternative Buckling Response (p. 504) in the MSC Nastran

Design Sensitivity and Optimization User’s Guide.

Listing 6-1 R3SGRT Subroutine

SUBROUTINE R3SGRT(GRPID,TYPNAM,NRESP, GRDTYP, ERROR)C ----------------------------------------------------------------------CC PURPOSE: VERIFY THE EXTERNAL RESPONSE TYPECC GRPID INPUT INTEGER - GROUP IDC TYPNAM INPUT CHARACTER*8 - NAME OF EXTERNAL RESPONSE TYPEC NRESP OUTPT INTEGER - NUMBER OF RESPONSES FOR THIS DRESP3C GRDTYP OUTPT INTEGER - INTEGER ARRAY OF LENGTH NRESP C INDICATING HOW GRADIENT ARE TO BEC COMPUTEDC = 2 THE USER WILL SUPPLY ANALYTIC C GRADIENTSC = -2 FINITE DIFFERENCE TECHNIQUES ARE USEDC ERROR INPUT/OUTPUT INTEGER -ERROR CODE FOR THE CALL.CC METHODC MATCH THE USER INPUT: TYPNAM WITH THE LIST OF AVAILABLEC EXTERNAL RESPONSE TYPES. IF NO MATCH IS FOUND, SET ERROR CODE.C SPECIFY THE NUMBER OF RESPONSES AND THE GRADIENT TECHNIQUE TO C BE USED FOR EACH CC CALLED BYC R3CGRTCC NOTE:C THE WRITER OF THIS ROUTINE IS RESPONSIBLE TO SPECIFYC NTYPES AND R3TYPE.C ----------------------------------------------------------------------CC VARIABLES PASSED INC INTEGER GRPID, ERROR, NRESP INTEGER GRDTYP(*) CHARACTER*8 TYPNAMCC LOCAL VARIABLESC INTEGER NTYPES, BADTYP PARAMETER(NTYPES=6) CHARACTER*8 R3TYPE(NTYPES)C DATA BADTYP/7554/ DATA R3TYPE/'USEVAR1 ','USEVAR10','USEALL', . 'USEMIXVS','FREQMOD ','EULJOH '/ ERROR = 0 DO 100 ITYPE = 1, NTYPES IF (TYPNAM .EQ. R3TYPE(ITYPE)) THEN NRESP = 2 GRDTYP(1) = 2



GRDTYP(2) = 2 GOTO 200 END IF100 CONTINUE ERROR = BADTYP200 CONTINUE RETURN END

This is an update of Listing 7-33 in the Design Sensitivity and Optimization User’s Guide and items in

bold are highlighted for the following discussion. There are two additional arguments for the subroutine:

• NRESP – indicates how many responses are to be calculated for this response type

• GRDTYP – indicates how gradients are to be supplied to an optimization or sensitivity analysis.

GRDTYP is a vector of length NRESP. Setting GRDTYP(iresp)=2 specifies that analytic gradients will

be provided while =-2 indicates that finite difference techniques will be required to compute gradient

information. In the Listing 6-1, the user has specified that there are two responses and that analytical

gradients will be supplied for each.

The corresponding R3SVALD subroutine is an update of Listing 7-34 in the MSC.Nastran Design

Sensitivity and Optimization User’s Guide:

Listing 6-2 R3SVALD Subroutine

SUBROUTINE R3SVALD(GRPID,TYPNAM, . NITEMS,ARGLIS, . NSIZE, ARGVAL, . NWRDA8,ARGCHR, . FORG,NRESP,NARG, . DR3VAL,SENVAL, . ERROR)C ----------------------------------------------------------------------CC PURPOSE: COMPUTE THE EXTERNAL RESPONSECC GRPID INPUT INTEGER - GROUP IDC TYPNAM INPUT CHARACTER*8 - NAME OF EXTERNAL RESPONSE TYPEC NITEMS INPUT INTEGER - DIMENSION OF ARRAY ARGLISC NSIZE INPUT INTEGER - DIMENSION OF ARRAY ARGVALC NWRDA8 INPUT INTEGER - DIMENSION OF CHARACTER ARRAY ARGCHRC ARGLIS INPUT INTEGER - ARRAY OF NO. OF ITEMS FOR EACH C ARGUMENT TYPE C ARGVAL INPUT DOUBLE - ARRAY OF ARGUMENT VALUES (EXCEPT C CHARACTERS) C ARGCHR INPUT CHARACTER*8 - ARRAY OF CHARACTER VALUES C NRESP INPUT INTEGER - NUMBER OF RESPONSESC FORG INPUT INTEGER - TYPE OF CALLC = 0 FUNCTION EVALUATIONC = 1 SENSITIVITY EVALUATION C NARG INPUT INTEGER - NUMBER OF ARGUMENTS NEEDING GRADIENTS C DR3VAL OUTPUT DOUBLE - VALUE OF THE EXTERNAL RESPONSESC SENVAL OUTPUT DOUBLE - MATRIX OF THE SENSITIVITY OF THE IRTH C RESPONSE TO THE IARGTH ARGUMENT

C ERROR INPUT/OUTPUT INTEGER -ERROR CODE FOR THE CALL.C

49CHAPTER 6

Optimization

C METHODC A)SET UP VARIOUS PARAMETERS FROM THE ARGUMENT LISTC B)IF FORG = 0 EVALUATE THE EXTERNAL RESPONSE BASED ON THE C GIVEN TYPNAMC C)ELSE IF FORG = 1 EVALUATE THE SENSITIVITIES OF THE EXTERNAL C RESPONSES TO THE ARGUMENTS THAT CAN VARY FOR C THE GIVEN TYPNAM C D)RETURN BADTYP ERROR IF TYPNAM IS NOT MATCHED HERE.CC NSIZE - THE NUMBER OF ARGUMENTS OR VALUES IN A DRESP3 ENTRYCC NSIZE=NV+NC+NR+NNC+NDVP1+NDVP2+NDVC1+NDVC2+NDVM1+NDVM2+NRR2C WHERE: C NV = NUMBER OF DESVARS NR = NUMBER OF DTABLESC NR = NUMBER OF DRESP1S NNC = NUMBER OF DNODE PAIRS C NDVP1 = NUMBER OF DVPREL1S NDVP2 = NUMBER DVPREL2S C NDVC1 = NUMBER OF DVCREL1S NDVC2 = NUMBER DVCREL2S C NDVM1 = NUMBER OF DVMREL1S NDVM2 = NUMBER DVMREL2S C NRR2 = NUMBER OF DRESP2S C NARG = NSIZE - NCCC CALLED BYC VARIOUSC ----------------------------------------------------------------------CC VARIABLES PASSED INC CHARACTER*8 TYPNAM, ARGCHR(NWRDA8) INTEGER FORG , NRESP INTEGER GRPID, NITEMS, NSIZE, ARGLIS(NITEMS), ERROR, NWRDA8 DOUBLE PRECISION ARGVAL(NSIZE), DR3VAL(*), SENVAL(NRESP,*) CCC LOCAL VARIABLESC INTEGER BADTYP, IDBG DOUBLE PRECISION PI, FAC, FACT, SLNDER DOUBLE PRECISION R,L,E,SIGMA,SIGMAC, RGYRAC DATA BADTYP /7554/, BADFG /7555/ C PI = 3.14159 PI2 = PI * PICC THE USER-SUPPLIED EQUATION TO DEFINE THE EXTERNAL RESPONSESC SIGMA = DRESP1, R=DESVAR, L, E AND SIGMAC = DTABLE CONSTANTSCC EULER : EULER= -SIGMA * (L/ RGYRA ) **2 / (PI**2 * E)C RGYRA = R / 2.0CC JOHNSON: JOHNSON = -SIGMA / (SIGMAC * FACTOR )C FACTOR = 1. - SIGMAC * (L/RGYRA)**2 /(4 * PI**2 * E) ERROR = 0CC SET UP PARAMETERS FOR VARIOUS ARGUMENT ITEMSC IF (TYPNAM .EQ. 'EULJOH ') THENC FUNCTION EVALUATION R = ARGVAL(1) L = ARGVAL(2)



E = ARGVAL(3) SIGMAC = ARGVAL(4) SIGMA = ARGVAL(5) RGYRA = R / 2.0 SLNDER = L / RGYRA FACT = PI * SQRT(2.0D0 * E / SIGMAC) FAC = 1.0D0 - SIGMAC * (SLNDER) ** 2 /(4.0D0 * PI2 * E ) IF ( FORG .EQ. 0 ) THENC FUNCTION EVALUATION C JOHNSON CRITERION DR3VAL(1) = -SIGMA / (SIGMAC * FAC)C EULER CRITERION DR3VAL(2) = -SIGMA * SLNDER**2 / (PI2 * E *10.0D0) ELSE IF ( FORG .EQ. 1 ) THENC GRADIENT EVALUATION DO 10 IRESP = 1, NRESP DO 20 IARG = 1, NARG SENVAL(IRESP,IARG) = 0.0D0 20 CONTINUE 10 CONTINUE C NOTE THAT ARGVAL(2,3 AND 4) ARE CONSTANT AND THEREFORE HAVE C ZERO SENSITIVITY DSLDR = -SLNDER / R DFACR = -SIGMAC * SLNDER * DSLDR / (2.0D0 *PI2 * E) C SENSITIVITY OF THE FIRST RESPONSE TO THE FIRST ARGUMENT SENVAL(1,1 ) = DFACR * SIGMA / ( SIGMAC * FAC ** 2)C SENSITIVITY OF THE SECOND RESPONSE TO THE FIRST ARGUMENT SENVAL(2,1) = -2.0D0*SIGMA * SLNDER * DSLDR / 1 (PI2 * E * 10.0D0)C SENSITIVITY OF THE FIRST RESPONSE TO THE SECOND ARGUMENT SENVAL(1,2) = - 1.0D0 / (SIGMAC * FAC) C SENSITIVITY OF THE SECOND RESPONSE TO THE SECOND ARGUMENT SENVAL(2,2) = -SLNDER**2 / (PI2 * E* 10.0D0) DO 25 IDBG =1,225 CONTINUE ELSE ERROR = BADFG ENDIF ELSE ERROR = BADTYP END IF RETURN END

There are three new arguments and one modified argument in the calling statement:

• FORG – input integer - flag to indicate whether this call is to perform function evaluations or

gradient evaluations. 0-function, 1-gradient

• NRESP – input integer - indicates how many responses are to be calculated for this response

type

• NARG – input integer -number of arguments requiring gradients

• DR3VAL – output real – vector of responses

• SENVAL, - output real – matrix of sensitivities

51CHAPTER 6

Optimization

DR3VAL is the modified argument in that it previously was a scalar and now is a vector. A comparison

with the listing in the User’s Guide shows that now two responses are being returned (one for the Euler

criteria and one for the Johnson criteria) rather than a single argument which was the most critical of the

two criteria. NARG is used to supply the number of columns in the SENVAL matrix and it is important

to note that any constant terms (i.e, those input using DTABLE) are not included in the count of NARG

even though they are in the ARGVAL vector. SENVAL has NRESP rows and NARG columns.

DR3VAL is output when FORG=0 while SENVAL is output when FORG=1. Additional discussion of

these arguments is provided in Guidelines and Limitations, 51.

Output

.f06 output associated with the DRESP3 has been altered in one subtle respect: a response number field

has been added to the print as a count of which of the multiple responses is associated with the print. As

an example, the

It is seen that a single DRESP3 entry has generated 10 responses. These are 2 responses in each five

elements that have the buckling criteria imposed on them. It is up to the user to decipher that RESP NO.

1 is the Johnson buckling criterion while RESP NO. 2 is the Euler criterion.


Modifying Existing Server Subroutines

The enhanced capability does not require any changes in the input files that have been developed to

utilize the DRESP3, but it does require changes in the R3SGRT and R3SVALD server subroutines. To

retain the current capability for an existing DRESP3, the changes required in the R3SGRT subroutine are

to:

1. Add arguments NRESP and GRDTYP

2. Type NRESP and GRDTYP as integers.

3. Once the appropriate TYPNAM has been selected, add NRESP = 1 and GRDTYP(1) = -2

---- RETAINED DRESP3 RESPONSES ----

----------------------------------------------------------------------------------------------------------------------- INTERNAL DRESP3 RESP RESPONSE GROUP TYPE LOWER UPPER ID ID NO LABEL NAME NAME BOUND VALUE BOUND ------------------------------------------------------------------------------------------------------------------------ 1 32 1 JOHNSON TESTGRP EULJOH N/A 1.4018E+00 1.0000E+00 1 32 2 JOHNSON TESTGRP EULJOH N/A 1.3761E+00 1.0000E+00 2 32 1 JOHNSON TESTGRP EULJOH N/A 1.4018E+00 1.0000E+00 2 32 2 JOHNSON TESTGRP EULJOH N/A 1.3761E+00 1.0000E+00 3 32 1 JOHNSON TESTGRP EULJOH N/A 1.4018E+00 1.0000E+00 3 32 2 JOHNSON TESTGRP EULJOH N/A 1.3761E+00 1.0000E+00 4 32 1 JOHNSON TESTGRP EULJOH N/A 1.4018E+00 1.0000E+00 4 32 2 JOHNSON TESTGRP EULJOH N/A 1.3761E+00 1.0000E+00 5 32 1 JOHNSON TESTGRP EULJOH N/A 1.4018E+00 1.0000E+00 5 32 2 JOHNSON TESTGRP EULJOH N/A 1.3761E+00 1.0000E+00



For the R3SVALD subroutine, the changes are to:

1. Add arguments FORG, NRESP, NARG, and SENVAL

2. Type FORG, NRESP and NARG as integers and DR3VAL(*) and SENVAL(NRESP,*) as

double precision

3. Replace the current DR3VAL = statements with DR3VAL(1) =.

4. Since FORG=1 is not supported, it is not necessary to specify any SENVAL output.

Other Guidelines

In R3SGRT, GRDTYP needs to be defined for all NRESP responses and the values must be either 2 or -

2. It is an error if any other value is used.

As mentioned previously, NARG is an input to R3SVALD and this value is determined from all the

DRESP3 arguments minus the constants and the string inputs. If a particular response is not a function

of one of the arguments, it is necessary to explicitly set the corresponding SENVAL output to zero. It is

a good practice to initialize the entire SENVAL array to 0.0.

It is important to realize that the gradients that are provided are for the responses with respect to the

DRESP3 arguments and not (necessarily) the design variables. This takes the burden of performing the

chain rule calculations from the user and uses existing Nastran operations to compute terms such as:

Instead, the R3SVALD subroutine provides the and terms and the remaining operations

are performed within Nastran.

Limitation

There is a current limitation that all GRDTYP’s for a particular TYPE must be the same, either -2 or 2.

The GRDTYP’s do not need to all be the same for all the DRESP3’s in an input file. That is, one can

specify analytic gradients for one TYPE and finite difference gradients for another type.

Validation and Verification

Checking that the gradients are correct is an important and challenging process. Tips for facilitating this

include:

1. Setting DSAPRT(END=SENS) = n will stop the run after printing the sensitivities of the

responses in set n.

2. Setting DSAPRT(START=1) = n will provide sensitivities for the response in set n on the first

design cycle.

3. One can use two different versions of a DRESP3 to have the program check on itself. One would

use finite difference gradients while the second would use analytic gradients. The results should

agree except for numerical rounding due to the finite difference calculation.

dr3

dxJJJJJJJJ

δr3

δxJJJJJJJJZ

δr3

δriJJJJJJJJ∑

δri

δxJJJJJJJH

δr3

δx⁄ δr3

δri

⁄

53CHAPTER 6

Optimization

Examples

Three test cases are discussed here. The first of these is ds13grad and is a variation of the dsoug13

example in External Response to Include Alternative Buckling Response (Ch. 7) in the MSC Nastran

Design Sensitivity and Optimization User’s Guide. The R3SGRT and R3SVALD subroutines listed

above are used in this example.

The second example is dresp3aa is a test example to demonstrate all the types of arguments that can be

included in a DRESP3. The DRESP3 input in this example is:

Listing 6-3 ds13grad

$ F101 = X1DRESP3 101 EXTERNR3TESTGRP USEVAR1 DESVAR 1 DTABLE CONST DRESP1 808 DNODE 2 1 DVPREL1 1 DVCREL1 3 DVMREL1 5 DVPREL2 2 DVCREL2 4 DVMREL2 6 DRESP2 909 $ F102 = R2DRESP3 102 EXTERNR3TESTGRP USEVAR10 DESVAR 1 DTABLE CONST DRESP1 808 DNODE 2 1 DVPREL1 1 DVCREL1 3 DVMREL1 5 DVPREL2 2 DVCREL2 4 DVMREL2 6 DRESP2 909 $ F103 = F(X1,CONST,R1,G,DVP1,DVC1,DVM1,DVP2,DVC2,DVM2,R2)$234567DRESP3 103 EXTERNR3TESTGRP USEALL DESVAR 1 DTABLE CONST DRESP1 808 DNODE 2 1 DVPREL1 1 DVCREL1 3 DVMREL1 5 DVPREL2 2 DVCREL2 4 DVMREL2 6 DRESP2 909 $ F104 = F(X,g,P1,C1,M1,p2,R2)DRESP3 104 EXTERNR3TESTGRP USEMIXVS DESVAR 1 DTABLE CONST DRESP1 808 DNODE 2 1



DVPREL1 1 DVCREL1 3 DVMREL1 5 DVPREL2 2 DVCREL2 4 DVMREL2 6 DRESP2 909 USRDATA thisisa teststringforaddingxxx$ F105 = F(X,R1)DRESP3 105 EXTERNR3TESTGRP FREQMOD DESVAR 1 DRESP1 505

The relevant part of the R3SGRT subroutine that goes with this input file is:

Listing 6-4 dresp3aa

nresp = 1 IF (TYPNAM .EQ. 'FREQMOD' ) then grdtyp(1) = 2 Else if (typnam .eq. 'USEVAR1' ) then grdtyp(1) = -2 ELSE IF (TYPNAM .EQ. 'USEVAR10') THEN grdtyp(1) = 2 ELSE IF (TYPNAM .EQ. 'USEALL') THEN grdtyp(1) = -2 ELSE IF (TYPNAM .EQ. 'USEMIXVS') THEN grdtyp(1) = 2 else ERROR = BADTYP endif

There is a single response for each DRESP3 and analytic gradients are to be provided for

TYPNAM=’FREQMOD’,USEVAR10’ and ‘USEMIXVS’

The relevant part of the R3SVALD subroutine is:

Listing 6-5 dresp3sig

if ( forg .eq. 1 ) thenc gradient evaluation do 10 iresp = 1, nresp do 20 iarg = 1, narg senval(iresp,iarg) = 0.0d0 20 continue 10 continue Endif IF (TYPNAM .NE. 'FREQMOD') THEN x = argval(1) const = argval(2) r1 = argval(3) g = argval(4) p1 = argval(5) c1 = argval(6) m1 = argval(7) p2 = argval(8) c2 = argval(9) m2 = argval(10)

55CHAPTER 6

Optimization

r2 = argval(11) END IF IF (TYPNAM .EQ. 'USEVAR1') THEN dr3val(1) = x+r1+r2 ELSE IF (TYPNAM .EQ. 'USEVAR10') THEN if ( forg .eq. 0 ) then dr3val(1) = r2 else senval(1,9) = 1.0d0 endif ELSE IF (TYPNAM .EQ. 'USEALL') THEN dr3val(1) = x+const+r1+g+p1+c1+m1+p2+c2+m2+r2 ELSE IF (TYPNAM .EQ. 'USEMIXVS') THEN if ( forg .eq. 0 ) then dr3val(1) = x+g+p1+c1+m1+p2+r2 else senval(1,1) = 1.0d0 senval(1,3) = 1.0d0 senval(1,4) = 1.0d0 senval(1,5) = 1.0d0 senval(1,6) = 1.0d0 senval(1,9) = 1.0d0 endif ELSE IF (TYPNAM .EQ. 'FREQMOD') THEN x = argval(1) r1 = argval(2) if ( forg .eq. 0 ) then dr3val(1) = x*r1 else senval(1,1) = r1 senval(1,2) = x endif ELSE ERROR = BADTYP END IF

It is expedient to zero out all the gradient values, whether they are needed or not. For the TYPNAM’s

that don’t support analytic gradients, it is only necessary to provide the response value in DR3VAL(1).

For the TYPNAM’s that do support analytic gradients, an if test on FORG is provided. For FORG=0, a

function evaluation is made while a gradient evaluation is made for FORG=1. Note that for TYPNAM=

‘USEVAR10’, the input file shows 11 inputs, 1 for each of the available “Flags” while the actual response

shown in R3SVALD only uses the DRESP2 argument, the eleventh ARGVAL. Furthermore, the gradient

calculation has a single non-zero result: senval(1,9) = 1.0d0, indicating that the sensitivity of the first

response to the ninth argument that can vary is 1.0. The constant term in the ARGVAL list and the

undesigned DNODE do not count as one of the NARG sensitivity arguments, hence the discrepancy

between eleven and nine.

A final example is entitled dresp3sig and demonstrates the feature that reorders the sensitivity

calculations when NRESP1>>NDVI. In this case, there are 181 DRESP1’s and 10 DESVAR’s so the

criteria is satisfied. The job has two DRESP3’s that have the same arguments but one has

TYPNAM=RSS and the other has TYPNAM=RSSA. The RSS response has its gradients calculated

using finite difference techniques while the RSSA uses analytical gradients. Since these are the same

response, the test case serves to demonstrate that the same sensitivity information is generated using

analytic or finite difference gradient techniques. The problem is too small to make any assessment of

the performance gains that have resulted from the third enhancement mentioned in the Introduction, 46.


Topometry Optimization56

Topometry Optimization

Introduction

Topometry optimization is an element-by-element sizing optimization. Unlike conventional sizing

optimization where all elements referencing a property entry are grouped as one design variable, each

designable element has an independent design variable in topometry optimization. Since element-by-

element optimization has many design variables, it may find a better design than conventional sizing

optimization. In previous versions of Nastran, the user can use the design variable Bulk Data entry

DESVAR and the relation of model property and design variables Bulk Data entry DVxREL1 to support

element-by-element sizing optimization. However, with this approach the user must generate a unique

property data entry for each element and perhaps prepare thousands of DESVAR and DVPREL1 entries.

With the topometry optimization capability released in MSC Nastran 2008 r1, the user can utilize a new

Bulk Data entry, TOMVAR, to select designable regions (model property or material property

identification number), design parameters (such as thickness of PSHELLs, or Young’s Modulus of

materials), input initial values, lower and upper bounds to perform element-by-element sizing

optimization. The MSC Nastran program internally generates DESVAR and DVPREL1 (and/or

DVMREL1) for each designed element. The implementation provides a very simple user interface to do

element-by-element sizing design optimization. In addition, topometry optimization supports the fully

stressed design algorithm in MSC Nastran. FSD is very efficient for certain problems with many stress

constraints.

Topometry optimization released in MSC Nastran 2008 r1 can be applied to all elements that can be

resized through Bulk Data entries DVPREL1 and DVMREL1. Those element types include not only

volume-based elements like CQUAD4 but also non-volume elements like CWELD, CBUSH, and

CFAST.

Topology optimization is another element-by-element optimization technology. However, topology

optimization and topometry optimization are fundamentally different. Topology optimization is a “0” or

“1” discrete element-by-element optimization methodology. Topology optimization can be used to

decide which element should be retained and which element should be discarded from the design space.

One the other hand, topometry optimization aims to get a continuous variation of the designed properties.

Although topometry optimization is not recommended for topology optimization tasks, it is observed

topometry optimization can be used to get “similar topological results” for some cases. It is particularly

useful for non-structural elements like CELAS, CFAST, and CBUSH that MSC Nastran topology

optimization does not support.

In a single optimization problem, it is allowable to resize (or shape, topology) certain properties while

topometry optimizing other properties.

Benefits• Topometry optimization is easy-to-use. One TOMVAR Bulk Data entry replaces many

thousands of DESVAR and DVxREL1 entries for large element-by-element design optimization

problems.

57CHAPTER 6

Optimization

• Topometry optimization is good to identify critical design regions.

• Topometry optimization is good to locate where to add/or remove material to improve structural

performance.

• Topometry optimization is good for finding the optimal location of spot welds. In particular,

topometry optimization is very useful for some properties that MSC Nastran topology does not

support; for example, PDAMP, PELAS, PMASS, PBUSH, PVISC, PGAP, PACBAR, and

PFAST.

Input

The TOMVAR Bulk Data entry is used to select a topometry designable region and designed property

name. The initial, lower, and upper bound of the designed property value are also specified on the

topometry entry. The program automatically generates one design variable for each element

referencing a property PID. The relationship between design variables and the element property

given by

where is the analysis model property value for the ith element. NE is the total number of elements

referencing to the property PID. The user must input an initial value (such as the analysis model input

property value). The default of lower bound (XLB) on is , and default of upper bound on

(XUB) is .

The topometry Bulk Data entry is:

Format:

Example:

Design all element's thickness referencing PSHELL ID = 5 with initial design = 10.0 ( input

element thickness), lower bound and upper bound .

Example:

Design all element's Young Modulus referred by PSHELL ID = 100 with initial design XINIT = 3.E+5,

XLB=1.0, and XUB= 1.0E+6.

N 2 3 4 5 6 7 8 9 10

TOMVAR ID TYPE PID PNAME

/FID

XINIT XLB XUB DELXV

TOMVAR 10 PSHELL 5 T 10.0

DVi

DVi

Pi

Pi DViZ i 1 NE,Z

XLB DVi XUB≤ ≤

Pi

DVi

0.5 DVi

⋅

DVi

1.5 DVi

⋅

t0

10.0Z

0.5 t0

⋅ 1.5 t0

⋅



Remarks:

1. Multiple TOMVAR’s are allowed in a single file.

2. Property name and FID > 0 can be used for element property values just like a Bulk Data entry

DVPREL1. Only property name can be used for material property values like DVMREL1. If a

property name is shared by both property and material (such as “A” for PROD and MAT1), this

name is taken as a material name. The user must provide a FID for property name (FID=4 for

PROD). PCOMP, PCOMPG, PBEAML, PBARL, PBMSECT, PBRSECT are not supported. If

material property name is selected, PSHELL (with multiple MID inputs) must reference a unique

material ID.

3. Combined topometry, topography, topology, sizing, and shape optimization is supported in a

single file. However, topometry and topology cannot reference the same property ID. It is possible

to topometry certain elements while sizing others. It is allowed to simultaneously design the same

elements with topometry and desvar (sizing and/or shape) variables but topometry and sizing

cannot reference the same property name.

4. The design response DRESP1=FRMASS (fractional mass) can be used for topometry

optimization. The initial FRMASS is defined as1.0 at the initial design specified on a TOPVAR

entry. For non-volume elements like CELAS, a artificial mass = 1.0 is assumed for each element.

TOMVAR 10 PSHELL 100 E 3.E+5 1.0 1.E+6

Field Contents

ID Unique topometry design region identification number. (Integer > 0)

TYPE Property entry type. Used with PID to identify the elements to be designed.

(Character: “PBAR”, “PSHELL”, “PSOLID”, etc. see Remark 2.)

PID Property entry identifier (Integer > 0). This PID must be unique for PIDs referenced

by other TOPVAR, DVPREL1, DVPREL2, DVMREL1, and DVMREL2 entries.

(Integer > 0). See Remark 2.

PNAME/FID Property name or property material name, such as “T”, “A”, “E”, and “GE”, or field

position of the property entry or word position in the element property table of the

analysis model. Property names that begin with an integer such as 12I/T**3 may

only be referenced by field position. (Character or Integer > 0. see Remark 2.)

XINIT Initial value. (Real or blank, no default). Typically, XINIT is defined to match the

mass target constraint (so the initial design does not have violated constraints) or the

analysis model input property value.

XLB Lower bound. (Real or blank; Default = blank). The default is XLB=0.5*XINIT.

XUB Upper bound. (Real or blank; Default = blank). The default is XLB=1.5*XINIT.

DELXV Fractional change allowed for the design variable during approximate optimization.

(Real > 0.0; Default = 0.5. See Remark 3.).

59CHAPTER 6

Optimization

Output

A regular SOL 200 summary table is produced. In addition, a Patran element result file jobname.des

contains the optimal design values for each element. This Patran element result file can be imported to

Patran a third party post-processor to display topometry optimization results. Two parameters DESCPH

and DESPCH1 are used to specify in SOL 200 when the optimized topometry results are written to the

jobname.des.

Guidelines and Limitations• BIGDOT is the default optimizer of topometry optimization since topometry optimization

usually involves many thousands of design variables. BIGDOT requires a Topology

Optimization license. For SOL 200 design optimization clients without access to topology

optimization, optimizer MSCADS, method=4 (SUMT) is recommended through the

optimization control Bulk Data entry DOPTPRM.

• Since SOL 200 adjoint design sensitivity analysis method does not support element responses

(such as stress), a direct design sensitivity analysis method is automatically selected for

problems with element response constraints. In this case, topometry optimization with element

response constraints are slow due to many design variables. Fully stressed design (FSD) can be

used for certain problems.

• Topology optimization can be used for analysis model properties PDAMP, PELAS, PMASS,

PBUSH, PVISC, PGAP, NSM, NSM1, PACBAR and PFAST. Topology optimization is limited

to analysis properties that can reference material property MAT1.

• P2 > 13 on DOPTPRM prints design variables in *.f06.

Example 1 - Three-bar Truss (tomex1.dat)

A simple sizing optimization example three-bar truss (a TPL file DSOUG1.dat) is used here to

demonstrate topometry optimization solved by the fully stressed design algorithm. Figure 6-1 shows the

three-bar truss that must be built to withstand two separate loading conditions. The objective is to

minimize structural weight and subjected to displacement and stress constraints. The sizing design

variables are the cross-sectional areas. The detailed descriptions of analysis model and design

DESPCH DESPCH specifies when the topometry optimized design values are written to the

element result history file jobname.des. The Default = 0 writes the last design cycle

only. DESPCH < 0 never. DEPSCH1 > 0 at every design cycle that is a multiple of

DESPCH and the last design cycle.

DESPCH1 DESPCH1 > 0, write all topometry designed and non-designed element values to the

element result history file jobname.des. 1.0 is assigned to the non-designed element

value. DESPCH1 < 0, write all topometry designed element values to the element

result history file jobname.des.



optimization model can be seen in Chapter 7 of the MSC Nastran Design Sensitivity and Optimization

User's Guide.

Figure 6-1 Three Bar Truss

The goal of this example is to show an alternate method of setting design variables by a TOMVAR entry.

The objective and constraints are not changed. In conventional sizing optimization, the set of DESVAR

and DVPREL1 entries define the relations Ai=1.0Xi (i=1, 2, 3) where A is the rod element cross-

sectional area and X is the design variable. In DSOUG1.dat, we have:

$...DESIGN VARIABLE DEFINITION$DESVAR ID LABEL XINIT XLB XUB DELXV(OPTIONAL)DESVAR 1 A1 1.0 0.1 100.0DESVAR 2 A2 2.0 0.1 100.0DESVAR 3 A3 1.0 0.1 100.0$$...DEFINITION OF DESIGN VARIABLE TO ANALYSIS MODEL PARAMETER $RELATIONS$DVPREL1 ID TYPE PID NAME PMIN PMAX C0 +$+ DVID1 COEF1 DVID2 COEF2 ...DVPREL1 10 PROD 11 A 1 1.0

DVPREL1 20 PROD 12 A 2 1.0DVPREL1 30 PROD 13 A 3 1.0

In DSOUG1.dat, rod elements 11 and 12 have different property groups. Then, the DLINK entry is used

to explicitly link the design variables 1 and 3 together. In this example, we try to do element-by-element

optimization. Thus, we take three design variables (rod element cross-sectional areas) as independent

variables. The rod elements 1 and 3 have the same property group (PROD=1). TOMVAR entry 1

61CHAPTER 6

Optimization

(Listing 6-6) is used to define two independent design variables with an initial value = 1.0 (and element

cross-sectional area = 1.0) for rod element 11 and 13 respectively. This is equivalent to four entries in

DSOUG1.dat:

DESVAR 1 A1 1.0 0.1 100.0DESVAR 3 A3 2.0 0.1 100.0DVPREL1 10 PROD 11 A 1 1.0DVPREL1 30 PROD 13 A 3 1.0

TOMVAR entry 2 (Listing 6-6) is used to define one independent design variable with an initial value =

2.0 (and element cross-sectional area = 2.0) for rod element 12. This is equivalent to two entries in

DSOUG1.dat:

DESVAR 2 A2 2.0 0.1 100.0DVPREL1 20 PROD 12 A 2 1.0

Input

The input data for this example is given in Listing 6-6.

Listing 6-6 Input File for Example 1

ID MSC TOMEX1 $ TIME 10 $SOL 200 $ OPTIMIZATIONCENDTITLE = THREE BAR TRUSS TOPOMETRY OPTIMIZATION SUBTITLE = 3 CROSS SECTIONAL AREAS AS DESIGN VARIABLESECHO = SORTSPC = 100DISP = ALLSTRESS = ALLDESOBJ(MIN) = 20 $ (DESIGN OBJECTIVE = DRESP ID)DESSUB = 21 $ DEFINE CONSTRAINT SET FOR BOTH SUBCASESANALYSIS = STATICSSUBCASE 1 LABEL = LOAD CONDITION 1 LOAD = 300SUBCASE 2 LABEL = LOAD CONDITION 2 LOAD = 310BEGIN BULK$$------------------------------------------------------------------------$ ANALYSIS MODEL$------------------------------------------------------------------------$$ GRID DATA$ 2 3 4 5 6 7 8 9 10GRID 1 -10.0 0.0 0.0GRID 2 0.0 0.0 0.0GRID 3 10.0 0.0 0.0GRID 4 0.0 -10.0 0.0$ SUPPORT DATA



SPC1 100 123456 1THRU3$ ELEMENT DATACROD 1 11 1 4CROD 2 12 2 4CROD 3 11 3 4$ PROPERTY DATAPROD 11 1 1.0PROD 12 1 2.0MAT1 1 1.0E+7 0.33 0.1$ EXTERNAL LOADS DATAFORCE 300 4 20000. 0.8 -0.6FORCE 310 4 20000. -0.8 -0.6$$------------------------------------------------------------------------$ DESIGN MODEL$------------------------------------------------------------------------$$...DESIGN TOPOMETRY DESIGN DEFINITION$TOMVAR, ID, PRYPE, PID, PNAME, XINIT, XLB, XUB, DELXV(OPTIONAL)TOMVAR, 1 , PROD, 11, 4 , 1., .1 , 100.0TOMVAR, 2 , PROD, 12, 4 , 2., .1 , 100.0$$...STRUCTURAL RESPONSE IDENTIFICATION$DRESP1 ID LABEL RTYPE PTYPE REGION ATTA ATTB ATT1 +$+ ATT2 ...DRESP1 20 W WEIGHTDRESP1 21 U4 DISP 12 4DRESP1 23 S1 STRESS PROD 2 1112$...CONSTRAINTS$DCONSTR DCID RID LALLOW UALLOWDCONSTR 21 21 -0.20 0.20DCONSTR 21 23 -15000. 20000.$$...OPTIMIZATION CONTROL (FULLY STRESSED DESIGN):$DOPTPRM FSDMAX 20 DESMAX 0 P1 1 P2 15$$.......2.......3.......4.......5.......6.......7.......8.......9.......0ENDDATA

63CHAPTER 6

Optimization

Output

A regular SOL 200 output can be found as:

Example 2 – Car Model Topometry Design

A real complex example car body is used here to demonstrate topometry optimization for graphical post-

processing. This example also shows that SOL 200 is able to deal with very large optimization problems.

The objective is to minimize structural compliance and keep weight unchanged. SOL 200 produces an

element thickness distribution file *.des that can be used by Patran or other post-processors to view

topometry optimization results.

*************************************************************** S U M M A R Y O F D E S I G N C Y C L E H I S T O R Y ***************************************************************

(HARD CONVERGENCE ACHIEVED)

NUMBER OF FINITE ELEMENT ANALYSES COMPLETED 17 NUMBER OF FULLY STRESSED DESIGN CYCLES COMPLETED 16 NUMBER OF OPTIMIZATIONS W.R.T. APPROXIMATE MODELS 0

OBJECTIVE AND MAXIMUM CONSTRAINT HISTORY-------------------------------------------------------------------------------------------------------------------------------- OBJECTIVE FROM OBJECTIVE FROM FRACTIONAL ERROR MAXIMUM VALUE CYCLE APPROXIMATE EXACT OF OF NUMBER OPTIMIZATION ANALYSIS APPROXIMATION CONSTRAINT-------------------------------------------------------------------------------------------------------------------------------

INITIAL 4.828427E+00 -3.234952E-01

1 FSD 3.862742E+00 N/A -1.543690E-01 2 FSD 3.225798E+00 N/A -7.883203E-03 .

16 FSD 2.741757E+00 N/A 1.664062E-04

DESIGN VARIABLE HISTORY ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- INTERNAL | EXTERNAL | | DV. ID. | ELEMENT ID | LABEL | INITIAL : 1 : 2 : 3 : 4 : 5 : ------------------------------------------------------------------------------------------------------------------------------------------------------------------ 1 | 1 | TOMVAR | 1.0000E+00 : 8.0000E-01 : 6.8794E-01 : 6.8306E-01 : 6.9978E-01 : 7.2284E-01 : 2 | 2 | TOMVAR | 2.0000E+00 : 1.6000E+00 : 1.2800E+00 : 1.0240E+00 : 8.1920E-01 : 6.5536E-01 : 3 | 3 | TOMVAR | 1.0000E+00 : 8.0000E-01 : 6.8794E-01 : 6.8306E-01 : 6.9978E-01 : 7.2284E-01 : -------------------------------------------------------------------------------------------------------------------------------



Figure 6-2 Optimal Thickness Distribution of Car Model - Note that this figure is meaningful

only when viewed in color.

65CHAPTER 6

Optimization

Topography (Bead or Stamp) Optimization

Introduction

Topography optimization (also called bead or stamp optimization) is used to generate a design proposal

for reinforcement bead patterns. In MSC Nastran 2008 r1, topography optimization is treated as a special

shape optimization and built on SOL 200 shape optimization technology. In topography optimization,

finite element grids are moved in as normal vectors to the shell surface or the user's given direction. New

algorithms were developed to generate shape design variables and shape basis vectors automatically

based on the user's provided bead dimension (minimum bead width, maximum bead height, and draw

angle). Since many design variables are generated in the topography optimization, the adjoint design

sensitivity analysis method and large scale optimizer play key roles in solving topography optimization

problems.

Benefits• Topography optimization is particularly powerful for designing sheet metal parts.

• Topography optimization can be used for all SOL 200 analysis types such as statics, normal

modes, buckling, complex eigenvalue, dynamic frequency response, and aeroelastic analyses.

Input

The BEADVAR Bulk Data entry is used to define topography design regions.

N 2 3 4 5 6 7 8 9 10

BEADVAR ID PTYPE PID MW MH ANG BF SKIP

“DESVAR” NORM/XD YD ZD CID XLB XUB DELXV

“GRID” NGSET DGSET

Field Contents

ID Unique topography design region identification number. (Integer > 0)

PTYPE Property entry type. Used with PID to identify the element nodes to be

designed. (Character: “PSHELL”, “PSHEAR”, “PCOMP”, or

“PCOMPG”.)

PID Property entry identifier. See Remark 1. (Integer > 0)

MW Minimum bead width. This parameter controls the width of the beads. The

recommended value is between 1.5 and 2.5 times the average element

width. See Remark 2. (Real > 0.0)

MH Maximum bead height (Real > 0.0). This parameter sets the maximum

height of the beads when XUB=1.0 (as Default). See Remark 2.


Topography (Bead or Stamp) Optimization66

ANG Draw angle in degrees (0.0 < Real < 90.0). This parameter controls the

angle of the sides of the beads. The recommended value is between 60 and

75 degrees.

BF Buffer zone ('yes' or 'no'; Default='yes'). This parameter creates a buffer

zone between elements in the topography design region and elements

outside the design region when BF='yes'. See Remark 3.

SKIP Boundary skip (“bc”, “load”, “both”, or “none”; Default = “both”). This

parameter indicates which element nodes are excluded from the design

region. “bc” indicates all nodes referenced by “SPC” and “SPC1” are

omitted from the design region. "load" indicates all nodes referenced by

“FORCE”, “FORCE1”, “FORCE2”, “MOMENT”, “MOMENT1”,

“MOMENT2”, and “SPCD” are omitted from the design region. “both”

indicates nodes with either “bc” or “load” are omitted from the design

region. “none” indicates all nodes associated with elements referencing

PID specified in field 4 are in the design region.

“DESVAR” Indicates that this line defines bead design variables that are automatically

generated.

NORM/XD, YD, ZD Bead vector (draw direction). Norm indicates the shape variables are

created in the normal directions to the elements. If XD, YD, and ZD are

provided, the shape variables are created in the direction specified by the

xyz vector defied by XD/YD/ZD that is given in the basic coordinate

system or CID. See Remark 4. (Character or Real, Default = blank = norm).

CID Coordinate system ID used for specifying draw direction (Blank or Integer

> 0; Default = blank = basic coordinate system)

XLB Lower bound. (Real < XUB or blank; Default = blank = 0.0). This ensures

the lower bound on grid movement equal to XLB*MH. See Remark 5.

XUB Upper bound. (Real > XLB or blank; Default = 1.0). This sets the upper

bound of the beads equal to XUB*MH. See Remark 5.

DELXV Fractional change allowed for the design variable during approximate

optimization. See Remark 3. (Real > 0.0; Default = 0.2)

“GRID” Indicates this line defines what element nodes can be added and/or removed

from topography design regions.

NGSET All grids listed on Bulk Data entry SET1 = NGSET are removed from

topography design regions.

DGSET All grids listed on Bulk Data entry SET1 = DGSET are added to topography

design regions.

Field Contents

67CHAPTER 6

Optimization

Remarks:

1. Multiple BEADVAR’s are allowed in a single file. Combined topometry, topology, topography,

sizing, and shape optimization is supported in a single file.

2. The user can provide allowable bead dimensions.

Bead Dimensions

3. It is recommended to set buffer zone = yes to maintain a good quality of mesh during topography

optimization.

4. The grids moves in the normal direction. All element grids referenced by one BEADVAR entry

must follow the right hand rule.

MW

MH

ANG

Design elements

Buffer zone

Nondesign elements

No buffer zone

Nondesign elements

Element Normal

Element normal vectors

Baseline surfaceOptimizedsurface



5. To force the grids to move only in the positive bead vector direction (one side of the surface), use

XLB = 0.0. To force the grids to move only in the negative bead vector direction (another side of

the surface), use XUB = 0.0. To allow girds to move in both positive and negative bead vector

directions, use XLB < 0.0 and XUB > 0.0. For example,

6. The jobname.op2 has topography results (shape change) that can be viewed in Patran. The text

file jobname.pch also has updated grid coordinates that can be copied to replace the grids in the

original file, and imported to Patran on other post-processors to view topography optimization

results.

Outputs

A regular SOL 200 design history summary table is produced. The jobname.op2 (with PARAM,POST,-

1) and jobname.pch can be imported to Patran and other post-processors to view topography optimization

results.

User defined draw vector

Baseline surfaceOptimizedsurface

User’s Provided Draw Direction

Bead Vector

Bead Vector

Optimized SurfaceBase Surface

(a) XLB = 0.0 and XUB = 1.0 (b) XLB = -1.0 and XUB = 0.0 (c) XLB = -1.0 and XUB = 1.0

Optimized Surface

69CHAPTER 6

Optimization

Guidelines and Limitations• BIGDOT is the default optimizer of topography optimization since topography optimization

usually involves many design variables. BIGDOT requires a Topology Optimization license. For

SOL 200 design optimization clients without access to topology optimization, the optimizer

MSCADS method=4 (SUMT) is recommended through the optimization Bulk Data entry

DOPTPRM.

• Since SOL 200 adjoint design sensitivity analysis method does not support element responses

(such as stress), a direct design sensitivity analysis method is automatically selected for

problems with element response constraints. In this case, topography optimization with element

response constraints are slow.

• Since adjoint design sensitivity analysis does not support rigid body elements (RBE1, RBE2,

RBE3, RROD, RBAR, RTRPLT, RSPLINE), all grids connected to rigid body elements must be

fixed in topography optimization for static and dynamic frequency response analyses.

• The minimum bead width and maximum bead height have significant effects on optimal

designs. A smaller minimum bead width results in more small beads.

• Mesh distortion is a challenge for topography optimization. It is recommended that a relatively

coarse mesh be used for highly curved areas.

• P2 > 13 on DOPTPRM prints design variables in *.f06

Example 3 – A Square (togex1.dat)

A square model shown in Figure 6-3 is used to demonstrate MSC Nastran 2008 r1 topography

optimization capabilities. The square is modeled with quadrilateral plate elements (CQUAD4) and is

fixed at all four edges. The objective is to maximize the first frequency of the structure with a given bead

dimension (minimum bead width = 10.0, maximum bead height = 20.0, draw angle = 70.0).

Figure 6-3 A Square



Input

The input data for this example is given in Listing 6-7. The Bulk Data entry 1 defines the topography

designable region. It is noticed that element normals are used for bead vectors (draw direction) and all

grids associated with the boundary condition are fixed during optimization. PARAM, POST, -1 outputs

results for Patran.

Listing 6-7 Input File for Example 2

$Topography opt example one SOL 200CENDTITLE = MSC Nastran job created on 28-Nov-07 ECHO = NONE$ Direct Text Input for Global Case Control DataDESOBJ(MAX) = 1SUBCASE 1$ Subcase name : Default SUBTITLE=Default SPC = 2 METHOD = 1 DISPLACEMENT(SORT1,REAL,PLOT)=ALL ANALYSIS=MODESBEGIN BULKEIGRL,1,,,20$ Direct Text Input for Bulk Data$ Elements and Element Properties for region : ps1$$ BEADVAR, ID, TYPE, PID, MW, MH, ANG, BF, SKIP.$BEADVAR, 1 , PSHELL, 1, 10., 20.0, 70.0, YES, BOTHDRESP1, 1, MODES, FREQ,,,1PARAM POST -1

Output

Figure 6-4 shows the topography optimized result by using Patran. The first frequency has increased from

0.568HZ at the initial design to 4.78 HZ.

Figure 6-4 Topography Optimal Design of A Square

71CHAPTER 6

Optimization

Randomization of an Input Data File

Introduction

The stochastic capability in MSC Nastran is the first step toward a complete and automatic self-

randomization of a finite element model. The current capability offers the possibility to automatically

distribute tolerances and uncertainties with minimum effort. This dramatically reduces the complexity

of large-scale stochastic simulations. In fact, once the stochastic option is triggered, the entire Bulk Data

file is automatically randomized without further user intervention. The resulting model, which needs to

be incorporated in a Monte Carlo Simulation loop (there are numerous off-the-shelf products which

support this capability) possesses unprecedented levels of realism.

In order to make full use of this new capability, it is necessary to use a multi-run environment which can

spawn a certain number of independent MSC Nastran executions, collect the results, and perform

statistical postprocessing. With the self-randomization capability in MSC Nastran, the user need only

define the outputs to be monitored, such as stresses, Eigenfrequencies, temperatures, displacements, etc.

There is no need to define inputs, as these are defined automatically by MSC Nastran. The

Randomization of an Input Data File functionality was a pre-release capability in MSC Nastran 2007 r1.

For MSC Nastran 2008 r1 this is now a production capability.

Benefits

It is sometimes assumed that the inputs to an MSC Nastran analysis are known exactly, and thus the

computed responses are exact. This is an invalid assumption since there will always be some uncertainty

in the input values with a corresponding variation in the results. MSC Nastran 2007 r1 provides a way

of introducing this uncertainty into the analysis process by automatically randomizing user input real

numbers based on the input values and statistical quantities that characterize the variation.

Input

The randomization capability is driven by a new STOCHASTICS Case Control command, as described

in the MSC Nastran Quick Reference Guide. If STOCHASTICS=ALL is used, all real quantities on

connectivity (those starting with C), material, and property Bulk Data entries, as well as any loads and

SPCD quantities, are modified based on a covariance factor of 0.05. A Gaussian distribution is used to

randomly select the perturbed quantity with the restriction than the value can be no more that a specified

number of standard deviations from the user input mean value. The default number of maximum

standard deviations is three.

Alternatively, the STOCHASTICS Case Control command can point to a STOCHAS Bulk Data entry

that provides the ability to selectively randomize different types of input quantities by means of user-

specified covariance values and user-prescribed numbers of allowed standard deviations. In this case,

only the types of input specified are randomized so that, for example, it is possible to randomize the load

inputs while leaving the property values unchanged.


Randomization of an Input Data File72

Output

There is no new output produced by this capability.


The randomization algorithm involves using a random number generator, a Gaussian distribution, a

prescribed covariance, and a mean value based on user input to determine a randomized value that is to

be used in the analysis. In order to avoid physically meaningless properties, the random value is

prescribed to be within m standard deviations of the input value, where m is a user input value with a

default value of 3.0.

The product of m * COV should not be greater than 1.0 to eliminate the possibility of the property

changing sign.

Any real value in the Bulk Data file will be randomized unless otherwise specified by the user. To keep

a particular field or fields from being randomized, the user must set them equal to a value of 0.0.

73CHAPTER 6

Optimization

Random Elimination of Element Types

Introduction

There has been a long-standing capability in MSC Nastran that allows the user to specify the random

elimination of a specified percentage of the CWELD elements contained in a bulk data file. This was

done using the PARAM CWRANDEL entry, with an additional CWDIAGP PARAM providing the

option of printing the IDs of the deleted elements. In the current release, this capability has been extended

to the CELASi, CFAST, CSEAM, and 1-D mass (CMASSi, CONM1, and CONM2) elements. In

addition, the user interface has been changed from the NASTRAN statement to the MDLPRM entry. The

Random Elimination of Element Types functionality was a pre-release capability in the MSC Nastran

2007 r1 release. For MSC Nastran 2008 r1 this is now a production capability.

Benefits

The ability to randomly delete various 1-D elements provides the user with some assessment of the

integrity of the design being modeled. For instance, if randomly deleting 20% of, say, of the CWELD

elements from a model caused a negligible change in the first ten natural frequencies, this was taken as

an indication of the robustness of the structure. Extending this approach to other element types provides

more options in this type of analysis. Placing the input on the MDLPRM entry consolidates that input so

that the user does not have to deal with the PARAM entry.

Input

The MDLPRM entry has ten new PARAMi names that support this capability. Five of these names (e.g,

DELELAS) select the element type to which the random elimination applies and the ratio to be deleted,

while an additional five names (e.g., PRTELAS) provide control as to whether the IDs of the deleted

elements are to be printed. The default is that the IDs will not be printed.

Output

There is no new output produced by this capability.


The deletion ratio is input as a real number between 0.0 and 1.0, with 0.0 indicating that no deletion is

to take place, while 1.0 eliminates all elements of the specified type.

It is possible that the elimination of a series of elements will introduce mechanisms in the structure that

will cause the analysis to fail. It is the user’s responsibility to determine whether this failure has occurred.

A likely scenario for the use of this capability would be to submit the same file multiple times and

determine the variation in the results. MSC does not offer an automated way of doing this at this time.


Enhancements in SOL 200 Optimization74

Enhancements in SOL 200 Optimization

Introduction

Capabilities of SOL 200 have been expanded to support:

• Using properties on PCOMPG as design variables

• Using responses from fluid model

• A modified objective function

Benefits

PCOMPG

The implementation provides a simple user interface to design and to track a particular ply over many

PCOMPGs which has the potential to significantly increase the productivity of engineers and designers.

Fluid Modes

Fluid modes can be utilized as design constraints in the optimization.

Objective Function Modification

Frequently, auto and aircraft manufacturers use SOL 200 to design just a tiny portion of the structure.

The mass of design portion can be 3 to 4 orders of magnitude smaller than the full structural mass.

Modifying the objective function provides a quick way avoid premature convergence.

Input

PCOMPG as Design Variables

The following KEYWORDs are added to the TYPE field of DVPREL1 Bulk Data entry.

For type=PCOMPG, PID field should have the ID of the PCOMPG entry and the PNAME/FID field can

have input of property name of fields or field number.

For type=GPLY, PID field should have the GPLYID on the continuation lines of PCOMPG and the

PNAME/FID field can only have T or THETA as input.

It should be noted that:

1 2 3 4 5 6 7 8 9 10

DVPREL1 ID TYPE PID PNAME/FID

PMIN PMAX C0

DVPREL1 100 PCOMPG or GPLY

PID or GPLYID

75CHAPTER 6

Optimization

1. When DVPREL1 has TYPE=GPLY, all PCOMPG entries with GPLYID will participate in the

design. The relationship between design variable and properties are defined by the following

equation

or is the original thickness or THETA angle on PCOMPG which is determined

automatically from the PCOMPG entry and is utilized as multiplier to the design variables. This

formulation allows a ply with same GPLYID on different PCOMPG’s to change in tandem

percentage-wise.

2. For with original value equal to 0.0, is taken as 1.0 and it is recommended

to have XINIT of DVID set to 0.0.

Example

$ $ $ $ $ $ $ $ $

DESVAR 1 T100000 1.00 0.01 100.0

$

DVPREL1 1 GPLY 100000 T

1 1.0

Fluid Modes as Design Constraints

With RTYPE=EIGN or FREQ, the default for PTYPE field is ‘STRUC’.


New parameter OBJMOD for DOPTPRM is implemented as a flag for objective function modification.

With DOPTPRM,OBJMOD,1, the original objective function value will be reset to 0.0. From the second

cycle onward, the objective function value represents the change of objective function with respect to the

original design.

The default value for OBJMOD is 0, meaning the total objective function value will be used.

1 2 3 4 5 6 7 8 9 10

DRESP1 ID LABEL RTYPE PTYPE REGION ATTA ATTB ATT1

ATT2 -etc.-

RTYPENew Option for

PTYPE Field

Response Attributes

ATTA ATTB ATTi

EIGN or FREQ STRUC or FLUID Normal Modes Number Approximation code

Pi C0Z T0i or THETA0i( )H DVIDj COEFj⋅( )∑⋅

T0 THETA0

THETA0 THETA0



Output

Output for the previous new features of SOL 200 is presented in the following paragraph. New features

are highlighted in BOLD characters.


A single set of DESVAR/DVPREL1 with GPLY will cover multiple PCOMPG entries which has a ply

with GPLYID. The output of comparison of analysis and design model, will then look like:

In the previous output, the number printed under the ‘PROPERTY ID’ column is the ID of PCOMPG.

Fluid Modes as Design Constraints

A sample of sensitivity for fluid mode responses is shown as follows. The output is produced via the

DSAPRT Case Control command.


With DOPTPRM,OBJMOD,1, objective function modification algorithm is activated. A sample of

objective function history is shown as follows. The output is available for all optimization jobs.

----- COMPARISON BETWEEN INPUT PROPERTY VALUES FROM ANALYSIS AND DESIGN MODELS -----

----------------------------------------------------------------------------------------------------------------------------PROPERTY PROPERTY PROPERTY ANALYSIS DESIGN LOWER UPPER DIFFERENCE SPAWNING TYPE ID NAME VALUE VALUE BOUND BOUND FLAG FLAG ----------------------------------------------------------------------------------------------------------------------------GPLY 12 T 5.400000E-03 5.400000E-03 N/A N/A NONE GPLY 22 T 5.400000E-03 5.400000E-03 N/A N/A NONE GPLY 33 T 5.400000E-03 5.400000E-03 N/A N/A NONE

**************************************************************************** * * * D E S I G N S E N S I T I V I T Y M A T R I X O U T P U T * * * * * * R E S P O N S E S E N S I T I V I T Y C O E F F I C I E N T S * * * **************************************************************************** ------------------------------------------------------------------------------------------------------------------------------- DRESP1 ID= 101 RESPONSE TYPE= FREQ MODE ID= 1 FLUID SEID= 0 SUBCASE RESP VALUE DESIGN VARIABLE COEFFICIENT------------------------------------------------------------------------------------------------------------------------------- 1 8.6023E+01 1 T 1.4641E-01 ------------------------------------------------------------------------------------------------------------------------------- DRESP1 ID= 102 RESPONSE TYPE= FREQ MODE ID= 2 FLUID SEID= 0 SUBCASE RESP VALUE DESIGN VARIABLE COEFFICIENT------------------------------------------------------------------------------------------------------------------------------- 1 2.6020E+02 1 T 4.4286E-01

77CHAPTER 6

Optimization

Guidelines• For type=GPLY, the recommended values for fields of DESVAR and DVPREL1 are

• The design model for exterior acoustic must be part of main input file which is after the ‘BEGIN

BULK’ entry. Any design model entries placed after ‘BEGIN BULK AFPM=xxxx’ are ignored.

• The effectiveness of DOPTPRM,OBJMOD,1 is not consistent. Hence, it is recommended only

for optimization problems that design just a tiny portion of the full structure.

Limitations• DVPREL2 must not be used to link design variable and properties of PCOMPG.

• Properties associated with ‘MICRO’ feature of PCOMPG are not supported in SOL 200.

Example


A simple file, d200pcg1, with multiple PCOMPG entries is utilized here to demonstrate the features

implemented for PCOMPG support in SOL 200. Some key bulk data entries are shown as follows:

$DESVAR 1 T100000 1.00 0.01 100.0$DVPREL1 1 GPLY 100000 T 1 1.0DVPREL1 2 PCOMPG 12 T2

OBJECTIVE AND MAXIMUM CONSTRAINT HISTORY --------------------------------------------------------------------------------------------------------------- OBJECTIVE FROM OBJECTIVE FROM FRACTIONAL ERROR MAXIMUM VALUE CYCLE APPROXIMATE EXACT OF OF NUMBER OPTIMIZATION ANALYSIS APPROXIMATION CONSTRAINT --------------------------------------------------------------------------------------------------------------- >>> OBJECTIVES in COLUMN 2/3 ARE INCREMENTAL TO OBJECTIVE OF ORIGINAL DESIGN = 1.0000E+05 <<< >>> ADD INCREMENTAL OBJECTIVE TO ORIGINAL TO ARRIVE AT REAL OBJECTIVE OF EACH CYCLE <<< ---------------------------------------------------------------------------------------------------------------

INITIAL 0.000000E+00 1.249923E+00

1 8.947921E-03 7.812500E-03 1.453339E-01 9.368142E-01

2 -1.010694E-02 -7.812500E-03 -2.936888E-01 1.003581E+00

3 -1.317651E-02 -1.562500E-02 1.567034E-01 3.951643E+00

4 -1.562500E-02 -1.562500E-02 0.000000E+00 3.951643E+00 ---------------------------------------------------------------------------------------------------------------

Bulk Data Entry Field Name Recommended Value

DESVAR X0 1.0

DVPREL1 C0 0.0

DVPREL1 COEF1 1.0



1 0.0054$pcompg,12,,,5000.,hill,0.0,,,,100000, 1, .0054, 45., yes,,400000, 1, .0054, 90., yes,,500000, 1, .0054, 90., yes,,600000, 1, .0054, 0.0, yes,700000, 1, .0054,-45., yes,800000, 1, .0054, 45., yespcompg,22,,,5000.,hill,0.0,,,,100000, 1, .0054, 45., yes,,300000, 1, .0054, 0.0, yes,,400000, 1, .0054, 90., yes,,500000, 1, .0054, 90., yes,600000, 1, .0054, 0.0, yes,800000, 1, .0054, 45., yespcompg,33,,,5000.,hill,0.0,,,,100000, 1, .0054, 45., yes,,200000, 1, .0054,-45., yes,,300000, 1, .0054, 0.0, yes,,400000, 1, .0054, 90., yes,500000, 1, .0054, 90., yes,800000, 1, .0054, 45., yes$

DVPREL1,1 links the thickness of ply 100000 in PCOMPG 12, 22 and 33 to DESVAR,1 and

DVPREL1,2 connects the thickness of PLY 400000 in PCOMPG,12 to DESVAR,1. Note that

DVPREL1,2 uses the existing equation for relation between design variables and properties while

DVPREL1,1 uses the new one shown in INPUT section. PCOMPG entries corresponding to the new

design are shown as follows,

79CHAPTER 6

Optimization

Fluid Modes as Design Constraints – TPL test file: d200fmd1.dat

The output section shows results from this file.

$ *************************************************************$ * *$ * CONTINUOUS DESIGN CYCLE NUMBER = 4 *$ * *$ *************************************************************$$$ UPDATED DESIGN MODEL DATA ENTRIES$DESVAR * 1T100000 3.37500000E+00 9.99999978E-03+D 1V*D 1V 1.00000000E+02$$ UPDATED ANALYSIS MODEL DATA ENTRIES$PCOMPG* 12 0.00000000E+00 5.00000000E+03** HILL 0.00000000E+00 0.00000000E+00 ** 100000 1 1.82250012E-02 4.50000000E+01** YES ** 400000 1 1.82250012E-02 9.00000000E+01** YES ** 500000 1 5.40000014E-03 9.00000000E+01** YES ** 600000 1 5.40000014E-03 0.00000000E+00** YES ** 700000 1 5.40000014E-03 -4.50000000E+01** YES ** 800000 1 5.40000014E-03 4.50000000E+01** YESPCOMPG* 22 0.00000000E+00 5.00000000E+03** HILL 0.00000000E+00 0.00000000E+00 ** 100000 1 1.82250012E-02 4.50000000E+01** YES ** 300000 1 5.40000014E-03 0.00000000E+00** YES ** 400000 1 5.40000014E-03 9.00000000E+01** YES ** 500000 1 5.40000014E-03 9.00000000E+01** YES ** 600000 1 5.40000014E-03 0.00000000E+00** YES ** 800000 1 5.40000014E-03 4.50000000E+01** YESPCOMPG* 33 0.00000000E+00 5.00000000E+03* * HILL 0.00000000E+00 0.00000000E+00 ** 100000 1 1.82250012E-02 4.50000000E+01* * YES * * 200000 1 5.40000014E-03 -4.50000000E+01* * YES * * 300000 1 5.40000014E-03 0.00000000E+00** YES * * 400000 1 5.40000014E-03 9.00000000E+01* * YES * * 500000 1 5.40000014E-03 9.00000000E+01* * YES ** 800000 1 5.40000014E-03 4.50000000E+01* * YES




Test file, d200zobj, is used. The design model covers just a tiny portion of the structure. The original

file produced following optimization history.

From column 3 of the previous output, the change in objective function is not visible at all. The same

output from d200zobj with DOPTPRM,OBJMOD,1 is shown as follows

Column 3 of the previous table shows the change of objective function. The original objective function

value can be found on the first line bracketed by ‘>>>’ and ‘<<<’. Note that the change of objective

function is 8 orders of magnitude smaller than the original objective function value.

OBJECTIVE AND MAXIMUM CONSTRAINT HISTORY --------------------------------------------------------------------------------------------------------------- OBJECTIVE FROM OBJECTIVE FROM FRACTIONAL ERROR MAXIMUM VALUE CYCLE APPROXIMATE EXACT OF OF NUMBER OPTIMIZATION ANALYSIS APPROXIMATION CONSTRAINT ---------------------------------------------------------------------------------------------------------------

INITIAL 1.000000E+05 1.249923E+00

1 1.000000E+05 1.000000E+05 0.000000E+00 9.361193E-01

2 1.000000E+05 1.000000E+05 0.000000E+00 1.003858E+00

3 1.000000E+05 1.000000E+05 0.000000E+00 3.077129E+00

4 1.000000E+05 1.000000E+05 0.000000E+00 3.077129E+00 ---------------------------------------------------------------------------------------------------------------

OBJECTIVE AND MAXIMUM CONSTRAINT HISTORY --------------------------------------------------------------------------------------------------------------- OBJECTIVE FROM OBJECTIVE FROM FRACTIONAL ERROR MAXIMUM VALUE CYCLE APPROXIMATE EXACT OF OF NUMBER OPTIMIZATION ANALYSIS APPROXIMATION CONSTRAINT --------------------------------------------------------------------------------------------------------------- >>> OBJECTIVES in COLUMN 2/3 ARE INCREMENTAL TO OBJECTIVE OF ORIGINAL DESIGN = 1.0000E+05 <<< >>> ADD INCREMENTAL OBJECTIVE TO ORIGINAL TO ARRIVE AT REAL OBJECTIVE OF EACH CYCLE <<< ---------------------------------------------------------------------------------------------------------------

INITIAL 0.000000E+00 1.249923E+00

1 8.947921E-03 7.812500E-03 1.453339E-01 9.368142E-01

2 -1.010694E-02 -7.812500E-03 -2.936888E-01 1.003581E+00

3 -1.317651E-02 -1.562500E-02 1.567034E-01 3.951643E+00

4 -1.562500E-02 -1.562500E-02 0.000000E+00 3.951643E+00 ---------------------------------------------------------------------------------------------------------------

Chapter 7: Aeroelasticity and Rotor Dynamic Improvements MSC Nastran 2008 r1 Release Guide

7 Aeroelasticity and Rotor

Dynamic Improvements

� A New Aerodynamic Interpolation Method

� External Spline Server

� Blade Vibration Analysis


A New Aerodynamic Interpolation Method82

A New Aerodynamic Interpolation Method

Introduction

Solution of the flutter equations entails interpolation to compute the aerodynamics at the exact reduced

frequency of the flutter solution as a function of the aerodynamics that have been computed explicitly

based on the ‘k’ (reduced frequency) values input on the MKAEROi entries. For many years, the

available interpolation schemes have been adaptations of the beam and surface spline methods used in

the splining of displacements and forces in aeroelasticity. Chapter 2.6 of the MSC Nastran Aeroelastic

Analysis User’s Guide documents these methods. All of these methods perform their interpolation based

only on the ‘k’ values and each term in the generalized aerodynamics matrix is weighted in the same way.

For MSC Nastran 2008 r1, an alternative interpolation is provided that interpolates each term in the

generalized aerodynamic matrix individually.

Inputs

The existing FLUTTER Bulk Data entry contains an IMETH field that allows the user to select between

L (linear interpolation on k-only) and S (surface interpolation on Mach number and k) methods. Under

this enhancement, an additional option (TCUB) has been provided to invoke a termwise cubic

interpolation technique. For legacy purposes, if the FLUTTER entry has a METH field of “PK”,

“PKNL”, “PKS” or “PKNLS” and the IMETH field is blank, S or L, the linear beam spline is used to

interpolate the aerodynamics as a function of reduced frequency. If IMETH is TCUB, the termwise cubic

spline technique is employed. Any other value of IMETH results in an error. If the flutter method is “K”

or “KE”, IMETH=S selects a surface spline on Mach and reduced frequency and IMETH=L selects a

linear method on reduced frequency and using the Mach number that is closest to the Mach number

specified on the FLFACT entry. It is an error to select METH = “K” or “KE” and IMETH=”TCUB”

Outputs

There are no new outputs as a result of this implementation.


The interpolation scheme involves determining weighting coefficients using cubic spline techniques

based on the k values entered on the MKAEROi entries and the generalized aerodynamics computed at

these k’s. During the PK flutter analysis, an estimate of the k value is made. The interpolation is then

performed using:

Qi j kes t( ) Qi j k0

( )Z Ci j

3Δk⋅ Ci j

2H( ) Δk⋅ Ci j

1H( )H Δk⋅

83CHAPTER 7

Aeroelasticity and Rotor Dynamic Improvements

where:

If only one value is provided for the MKAEROi input, no interpolation is performed and the

aerodynamics are invariant.

If the value falls outside the range of k’s input using the MKAEROi entries, no extrapolation is

performed. Instead, the aerodynamics at the lowest input k value are used if the desired k is lower than

the input k’s and the aerodynamics at the highest input k value are used if the desired k is higher than any

input k’s.

For sensitivity analysis, it is necessary to provide the sensitivity of the aerodynamics due to a change in

. Differentiation of the equation above gives:

If only one value is provided of if the falls outside the range of MKAEROi values, the sensitivity

is zero.

A convenient way to check interpolation using the TCUB method with the beam spline method

(IMETH=L) is to perform a flutter analysis with two subcases with the only difference being the IMETH

value. The flutter summary results should be close, but not identical. DIAG 39 can be turned on around

the FA1 module to provide debug data for the flutter analysis while DIAG 30 will print even more data.

Turning DIAG 30 and DIAG 39 on around the DSFLTE module in the FLUTSENS dmap will provide

information on the sensitivity analysis. It is cautioned that the output is particularly voluminous for the

sensitivity diagnostics.

IMETH=TCUB is only supported for the ‘PK’ method of flutter analysis and its variants, i.e., it is not

supported for the ‘K’ and ‘KE’ methods.

Examples

Two examples are available with the release demonstrating this new capability. The first is named

csint.dat and is a variation of the simple HA145A example found in the MSC Nastran Aeroelasticity

User’s Guide. An extra subcase has been provided that repeats the PK flutter analysis of the example

= A term in the generalized aerodynamic matrix. Real and imaginary terms are splined

separately

= k at which aerodynamics are required

= largest k value from the MKAEROi input that is

=

= Interpolation coefficients determined using a cubic spline (1,2,3 are superscripts, not

exponents.)

Qi j

kest

k0

kest<

k kest koÓ

Cij

1 2 3, ,

k

kes t

k

dQi j kes t( )

dkJJJJJJJJJJJJJJJJJJJJJJJJJJ 3.0 C⋅ i j

3Δk⋅ 2.0 C⋅ i j

2H( ) Δk⋅ Ci j

1HZ

k kes t


A New Aerodynamic Interpolation Method84

while setting IMETH to TCUB. A comparison of the flutter summary results for the two examples show

virtually identical results.

The second example is entitled cintopt.dat and is a variation of the HA200B example from the same

User’s Guide. In this case, the flutter subcases have been converted from using the beam spline

interpolation to using the new TCUB interpolation. Again, there is virtually no change in the results.

85CHAPTER 7


External Spline Server

Introduction

The external spline evaluation capability that was introduced with MSC Nastran 2007 r1 required that

every term in the server-generated spline matrix be stored in memory. This limited the capability since

very large, but very sparse, spline matrices would not fit into the available memory.

With this release, the API was updated to allow the spline matrix to be stored in a sparse format. The

fully-populated spline matrix format is still supported.

Inputs

No changes were made to the Nastran input file or to how the external spline server is used.

API Changes

The interface between Nastran and an external spline server was modified to support the sparse matrix

format.

Two changes were made to the calling sequence of the main spline server interface routine (sxsevd.c),

they are noted in bold and a slightly larger font:

void sxsevd ( INTEGER group_id, /* Group id */ INTEGER spline_id, /* Spline id */ INTEGER *usage, /* Usage string (stored as hollerith) */ INTEGER n_int_data, /* Number of integer data */ INTEGER *int_data, /* Integer data */ INTEGER n_real_data, /* Number of real data */ MACHINEPRECISION *real_data, /* Real data */ INTEGER n_char_data, /* Number of character data */ INTEGER *char_data, /* Character data (stored as hollerith) */ INTEGER n_dep_grid, /* Number of dependent grids */ INTEGER *dep_grid_id, /* Dependent grid ids */ MACHINEPRECISION *dep_grid_xyz, /* Dependent grid x,y,z locations */ INTEGER n_indep_grid, /* Number of independent grids */ INTEGER *indep_grid_id, /* Independent grid ids */ MACHINEPRECISION *indep_grid_xyz, /* Independent grid x,y,z locations */ INTEGER n_dep_elem, /* Number of dependent elements */ INTEGER *dep_elem, /* Dependent element table */ INTEGER n_indep_elem, /* Number of independent elements */ INTEGER *indep_elem, /* Independent element table */ char *command_line, /* Optional command line argument */ char *connect_data, /* Optional connect data */ INTEGER *ginfo, /* Output information about the spline matrix */ MACHINEPRECISION **gmat, /* The computed spline matrix */ INTEGER *error) { /* Error code */

1. A new integer parameter called ginfo is now output. This variable stores the total number of

nonzero terms in the spline matrix if it is stored in the sparse format. ginfo should have a value

of zero if the spline matrix is stored in the fully-populated format.


External Spline Server86

2. Previous versions of Nastran allocated the memory for the spline matrix on the client (Nastran)

side of the problem. With the new version, the client does not know if the server will be storing

the spline matrix in the sparse or full formats. Therefore, it is now the server’s responsibility to

allocate the memory to store the spline matrix. As a result of this change, the gmat variable,

which was previously a pointer is now a pointer to a pointer.

Sparse Matrix Format

If the sparse format is used to store the spline matrix, then the data must be stored in gmat in triplets of

(row number, column number, value) for each nonzero term in the spline matrix:

The ginfo variable must store the number of nonzero terms (n) in the spline matrix. The sparse gmat

will store numbers total.

Upgrading an Existing Spline Server

This section provides one method for upgrading an MSC Nastran 2007 r1 spline server to be compatible

with R3. The experienced C programmer may wish to implement the changes differently. It will be

assumed that the spline matrix will be stored in the fully-populated format.

1. Update the calling arguments of sxsevd.c to be exactly as listed above.

2. Declare a local variable to store the spline matrix:

MACHINEPRECISION *server_gmat=NULL;

3. Set the value of ginfo:

*ginfo = 0;

4. Allocate the memory to store the spline matrix.

gmat

Row number for value 1

Collumn number for value 1

Value 1

Row number of value 2

Column number for value 2

Value 2

.

.

.

Row number for value n

Column number for value n

Value n

Z

3 n×( )

87CHAPTER 7


Blade Vibration Analysis

In prior versions of Nastran; MSC Nastran 2007 r1, special options were added to SOL 106 to support

blade vibration analysis but were not documented in the MSC Nastran Release Guide or MD Nastran

Quick Reference Guide. The options are documented here for your convenience.

• Frequency (Forced) Response Analysis - in addition to the current normal modes analysis in

SOL 106, the user can request a frequency response analysis. Both the normal modes and

frequency response analysis are requested with a separate subcase followed by the Case Control

commands ANALYSIS=MODES (Ch. 4) and ANALYSIS=DFREQ (Ch. 4) in the MSC Nastran

Quick Reference Guide.

• “Hot-to-Cold” Analysis - allows the user to input the “stressed” or “hot” (deformed) geometry

using standard Bulk Data input and then “unload” the structure to determine the “unstressed” or

“cold” shape. See the description of the Case Control command ANALYSIS=HOT2COLD

(Ch. 4) and user parameters HTOCITS (Ch. 5), HTOCPRT (Ch. 5), and HTOCTOL (Ch. 5) in the

MSC Nastran Quick Reference Guide.

• Tangential Acceleration and Coriolis Follower Forces in Frequency Response Analysis - Include

the effects of the tangential acceleration and Coriolis follower forces in the nonlinear differential

stiffness matrix to be used frequency (forced) response analysis. See the description of user

parameter HTOCITS (Ch. 5) in the MSC Nastran Quick Reference Guide.

These options enable the analyses of a rotating nonsymmetrical structure connected to a nonsymmetrical

stationary structure. The rotating component will be assumed to be spinning at a constant rate. The

procedure permits dynamic response calculations of the bypass fan, compressor, and turbine blades for

aerojet engines. It also allows analyses of rotating wing aircraft. The methodology can also be used for

dynamic response of the crankshaft/engine block of a reciprocating engine.


Blade Vibration Analysis88

msc nastran 2008 r1 release guide

Documents

cendspc100load1000dispallbegin

finite difference

demonstration

maximum constraint

finite difference

user1 2nd

user99 100th

bulk data