msc nastran 2014 release guide

MSC Nastran 2014

Release Guide

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imerftware Corporation reserves the right to make changes in specifications and other information contained ocument without prior notice.cepts, methods, and examples presented in this text are for illustrative and educational purposes only, not intended to be exhaustive or to apply to any particular engineering problem or design. MSC Software tion assumes no liability or responsibility to any person or company for direct or indirect damages resulting use of any information contained herein.cumentation: Copyright 2014 MSC Software Corporation. Printed in U.S.A. All Rights Reserved.ice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or ion of this document, in whole or in part, without the prior written consent of MSC Software Corporation is d.

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ion. Please see A Fast and High Quality Multilevel Scheme for Partitioning Irregular Graphs. George and Vipin Kumar. SIAM Journal on Scientific Computing, Vol. 20, No. 1, pp. 359-392, 1999. MPICH2 is ed by Argonne National Laboratory. Copyright + 2002 University of Chicago.ytran, Marc, MSC Nastran, Patran, the MSC Software corporate logo, OpenFSI, e-Xstream, Digimat, and ng Reality are trademarks or registered trademarks of the MSC Software Corporation in the United States ther countries.

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C o n t e n t sMSC Nastran 2014 Release Guide

Contents

1

2 PrefacePreface to the MSC Nastran 2014 Release Guide 8

List of Books 9

Technical Support 10

Training and Internet Resources 11

MSC Nastran Documentation 12

Overview of MSC Nastran 2014

Linear AnalysisSET for Rigid Elements 6

Linear Combination of SUBCASEs using SUBCASE IDs 10

Fatigue Analysis of Spot Welds 12

Fatigue Analysis of Seam Welds 20

Use of RPC Files in Fatigue Analysis 28

Block Loading in Fatigue Analysis 30

MAT1 References on MATFTG Entry 32

2-Pass and 3-Pass Fatigue Analysis 35

Fatigue Analysis with Multiaxial Assessment 40

Axisymmetric Harmonic Concentrated Mass Element 47

Enhancements to the External Superelement Capability 50

Enhancements for Porous-Elastic Material (PEM) 64

MSC Nastran 2014 Release Guide

4

Data Recovery of Ply Level Responses at Extreme Ends in Composites 66

3 Advanced Nonlinear (SOL 400)

4

5

6 Introduction 70

Linear Analysis with SOL 400 71

Nonlinear Analysis with Linear Perturbations with SOL 400 75

Contact Enhancements in MSC Nastran 2014 77

Contact Test Cases 78

OpenFSI Enhancements 81

Abaqus to MSC Nastran translator 82

Explicit Nonlinear (SOL 700)Overview 84

Enhancement 1: Enhance Partitioner 85

Enhancement 2: Wetted Solid - Automatic Coupling Surface Creation From a Group of Solid Elements 86

Enhancement 3: Improve Performance for Models with Very High Number of Segments in the Coupling Surface 87

Numerical Methods and High Performance ComputingSOL 400 Performance Improvements 92

FASTFR Performance Improvements 96

Krylov Solver Performance Improvements 99

Random Analysis Performance Improvements 103

OptimizationFatigue Responses in Spot and Seam Welds 106

Design of Loads in SOL 200 112

5Contents

7 MiscellaneousMonitor Point Enhancements 120

8 Platform SupportSupported Hardware and Operating Systems 124


6

MSC Nastran Release Guide

PrefacePreface

Preface to the MSC Nastran 2014 Release Guide 8 List of Books 9 Technical Support 10 Training and Internet Resources 11 MSC Nastran Documentation 12

8 MSC Nastran Release Guide

Preface to the MSC Nastran 2014 Release GuideThis Release Guide contains descriptions for the MSC Nastran 2014 version, and supersedes the MSC Nastran 2013.1 Release Guide.

9Preface

List of BooksBelow is a list of some of the MSC Nastran documents. You may find any of these documents from MSC Software at http://s

imcompanion.mscsoftware.com/infocenter/index?page=home.

Installation and Release GuidesInstallation and Operations Guide Release Guide

GuidesReference Books

Quick Reference GuideDMAP Programmers GuideReference Manual

Users GuidesGetting StartedLinear Static AnalysisDynamic AnalysisMSC Nastran Demonstration Problems Nastran Embedded Fatigue Users GuideSuperelementsDesign Sensitivity and OptimizationNon Linear User's Guide (SOL 400)Implicit Nonlinear (SOL 600)Explicit Nonlinear (SOL 700)User Defined ServicesThermal AnalysisAeroelastic Analysis


Technical SupportFor technical support phone numbers and contact information, please visit: http://w

Suppo

The Simfind proknowlerelevanIt is a sallows ww.mscsoftware.com/Contents/Services/Technical-Support/Contact-Technical-Support.aspx

rt Center (http://simcompanion.mscsoftware.com)

Companion link above gives you access to the wealth of resources for MSC Software products. Here you will duct and support contact information, product documentations, knowledge base articles, product error list,

dge base articles and SimAcademy Webinars. It is a searchable database which allows you to find articles t to your inquiry. Valid MSC customer entitlement and login is required to access the database and documents. ingle sign-on that gives you access to product documentation for complete list of products from MSC Software, you to manage your support cases, and participate in our discussion forums.

11Preface

Training and Internet ResourcesMSC Software (www.mscsoftware.com)

MSC Smarket

http://s

The Simfind proknowlerelevanIt is a siallows

http://w

The MSrecomm

NAS10

This coMSC Nedited uAt the c

NAS10

This coclass, yRBAR,materiachecks

NAS12

This seof strucmodel Patran Nastranrequireoftware corporate site with information on the latest events, products and services for the CAD/CAE/CAM place.

imcompanion.mscsoftware.com

Companion link above gives you access to the wealth of resources for MSC Software products. Here you will duct and support contact information, product documentations, knowledge base articles, product error list,

dge base articles and SimAcademy Webinars. It is a searchable database which allows you to find articles t to your inquiry. Valid MSC customer entitlement and login is required to access the database and documents. ngle sign-on that gives you access to product documentation for complete list of products from MSC Software, you to manage your support cases, and participate in our discussion forums.

ww.mscsoftware.com/msc-training

C-Training link above will point you to schedule and description of MSC Seminars. Following courses are ended for beginning MSC Nastran users.

1A - Linear Static and Normal Modes Analysis using MSC Nastran

urse serves as an introduction to finite element analysis. It includes discussion of basic features available in astran for solving structural engineering problems. In this course, all finite element models will be created and sing a text editor, not a graphical pre-processor. Proper data structure of the MSC Nastran input file is covered. onclusion of seminar, the student will be familiar with fundamental usage of MSC Nastran.

1B - Advanced Linear Analysis using MSC Nastran

urse is a continuation of NAS101A - Linear Static and Normal Modes Analysis using MSC Nastran. In this ou will learn: Theory of buckling analysis and how to perform a buckling analysis About rigid elements - MPC, RBE2, and RBE3 Modeling with interface element CINTC and connectors Lamination theory and composite ls MSC Nastran composite theory Failure theories Linear contact and permanent glued contact Different model Modeling tips and tricks

0 - Linear Static Analysis using MSC Nastran and Patran

minar introduces basic finite element analysis techniques for linear static, normal modes, and buckling analysis tures using MSC Nastran and Patran. MSC Nastran data structure, the element library, modeling practices,

validation, and guidelines for efficient solutions are discussed and illustrated with examples and workshops. will be an integral part of the examples and workshops and will be used to generate and verify illustrative MSC models, manage analysis submission requests, and visualize results. This seminar provides the foundation

d for intermediate and advanced MSC Nastran applications.


MSC Nastran DocumentationFor quick access to the full set of MSC Nastran Documentation on Windows, one can:

1.2.3.Go to your MSCNastran_Installation_DIR\msc2014\Doc\pdf_nastran\Click on nastran_library.pdf and use the Right Mouse Button to Create ShortcutMove the shortcut to your Windows Desktop

Chapter 1: Overview of MSC Nastran 2014MSC Nastran Release Guide

1 Overview of MSC Nastran 2014


MSC Software is pleased to introduce you to the exciting new technologies in MSC Nastran 2014, the premier and trusted CAE solution for aerospace, automotive, defense, and manufacturing industries worldwide. This release includes new features and enhancements in Contact, Fatigue, High Performance Computing, Acoustics, Aeroelasticity, and Exinteger

Line

Adva

Expl

Numplicit Nonlinear SOL 700. This release will also change the default mode in MSC Nastran to i8, or 64-bit s, instead of the previous default of i4, or 32-bit integers.k

ar AnalysisSET for Rigid Elements , 6

Linear Combination of SUBCASEs using SUBCASE IDs, 10

Fatigue Analysis of Spot Welds, 12

Fatigue Analysis of Seam Welds, 20

Use of RPC Files in Fatigue Analysis, 28

Block Loading in Fatigue Analysis, 30

MAT1 References on MATFTG Entry, 32

2-Pass and 3-Pass Fatigue Analysis, 35

Fatigue Analysis with Multiaxial Assessment, 40

Axisymmetric Harmonic Concentrated Mass Element, 47

Enhancements to the External Superelement Capability, 50

Enhancements for Porous-Elastic Material (PEM), 64

nced Nonlinear (SOL 400)Linear Analysis with SOL 400, 71

Nonlinear Analysis with Linear Perturbations with SOL 400, 75

Contact Enhancements in MSC Nastran 2014, 77

Contact Test Cases, 78

Composite Enhancements in MSC Nastran 2014, 79

icit Nonlinear (SOL 700)Enhancement 1: Enhance Partitioner, 85

Enhancement 2: Wetted Solid - Automatic Coupling Surface Creation From a Group of Solid Elements, 86

Enhancement 3: Improve Performance for Models with Very High Number of Segments in the Coupling Surface, 87

erical Methods and High Performance ComputingSOL 400 Performance Improvements , 92

3Overview of MSC Nastran 2014

FASTFR Performance Improvements, 96

Krylov Solver Performance Improvements, 99

Opti

MiscRandom Analysis Performance Improvements, 103

mizationFatigue Responses in Spot and Seam Welds, 106

Design of Loads in SOL 200 , 112

ellaneousMonitor Point Enhancements, 120


Chapter 2: Linear Analysis

2 Linear Analysis SET for Rigid Elements 6 Linear Combination of SUBCASEs using SUBCASE IDs 10 Fatigue Analysis of Spot Welds 12 Fatigue Analysis of Seam Welds 20 Use of RPC Files in Fatigue Analysis 28 Block Loading in Fatigue Analysis 30 MAT1 References on MATFTG Entry 32 2-Pass and 3-Pass Fatigue Analysis 35 Fatigue Analysis with Multiaxial Assessment 40 Axisymmetric Harmonic Concentrated Mass Element 47 Enhancements to the External Superelement Capability 50 Enhancements for Porous-Elastic Material (PEM) 64 Data Recovery of Ply Level Responses at Extreme Ends in

Composites 66

6 Linear AnalysisSET for Rigid Elements

SET for Rigid Elements

IntroIn all putilizedparticuonly fo

BeneWith M

UserThe rig

Case CRigid Edescrip

Remar1.2.

3.

Param

RBSEDefaul

This pain conjuof PAR

MPCductionast MSC Nastran versions, rigid elements (i.e., RBE1, RBE2, RBAR, etc.) have been and continue to be highly in finite element analysis. Until now, analysts did not have the tools to select a subset of rigid elements for a lar SUBCASE. MSC Nastran 2014 provides a tool for the users to define a set of rigid elements which are used r a SUBCASE.

fitsSC Nastran 2014, user can define a group of rigid elements to use specifically for a SUBCASE.

Interfaceid element selections tool is built on the familiar MPC case control command and SET3 bulk data entry.

ontrol lement Selection. See the MPC (Case) (p. 436) in the MSC Nastran Quick Reference Guide for the full tion.

ks:In cyclic symmetry analysis, this command must appear above the first subcase command.Multiple boundary conditions (MPC sets) are not allowed in superelement analysis. If more than one MPC set is specified per superelement (including the residual), then the second and subsequent sets will be ignored.In addition to select MPC/MPCADD bulk data entries, MPC=n can also be used to select a group of rigid elements for the analysis via SET3,n bulk data entry with RBEin or RBEex in DES field of SET3 bulk data entry.

eter

TPRTt=0

rameter controls the printout of rigid element IDs that are included in the analysis. Note that this function works nction with the rigid element selection via MPC=n in case control and SET3,n,RBxx in bulk data. An example

AM,RBSETPRT,1 output is shown as follows:

(Case) Multipoint Constraint Set Selection

7Linear AnalysisSET for Rigid Elements

*** USER INFORMATION MESSAGE 2051 (GP4) RIGID ELEMENTS INCLUDED VIA MPC 1 IN CASE CONTROL AND SET3 1 IN BULK DATA. RBAR 2501 2502 2503 RBE2 106 107 108 109 206 207 208 209 210 307 RBE2 308 309 310 311

Bulk DSee theata Entry SET3 (p. 3521) in the MSC Nastran Quick Reference Guide for the full description.

8 Linear AnalysisSET for Rigid Elements

Forma

Alterna

Additio1.

2.

3.

4.5.6.

SET3 Labeled Set Definition

1SET3

FieldSIDDES

IDit:

te Format and Example:

nal Remarks:When a SET3 is referenced by a ELSIDi or XELSIDi field on an FTGDEF entry, only ELEM may be used. When SET3 is referenced by a NDSIDi field on a FTGDEF entry, only GRID may be used. When DES="RBEin", the SET selects rigid elements to be included for MPC=sid and is applicable to Rigid Element types of RBAR, RBAR1, RBE1, RBE2, RBE2GS, RBE3, RROD, RSPLINE, RSSCON, RTRPLT and RTRPLT1. Note that Rigid Elements with duplicate ID across Rigid Element types will all be utilized.For DES="RBEex", the SET selects rigid elements to be excluded for MPC=sid and is applicable to Rigid Elements types of RBAR, RBAR1, RBE1, RBE2, RBE2GS, RBE3, RROD, RSPLINE, RSSCON, RTRPLT and RTRPLT1.Note that "RBEin" and "RBEex" are mutually exclusive and should not appear together for a single SET. By default, without SET3,mpcid,RBExx, all Rigid Elements in the input deck will be used.SET selection for rigid elements does not cover additional IDs on MPCADD bulk data entry.

2 3 4 5 6 7 8 9 10SID DES ID1 ID2 ID3 ID4 ID5 ID6ID7 ID8 -etc-

ContentsUnique identification number. (Integer>0)Set description (Character). Valid options are GRID, ELEM, POINT, PROP, RBEin, and RBEex.Identifiers of grids points, elements, points or properties. (Integer > 0)

9Linear AnalysisSET for Rigid Elements

Test CasesThe following test decks are available in the msc20140/nast/tpl/intload subdirectory of MSC Nastran installa

tion directory.

Rbset1.datRbset2.datRbset3.datRbset4.dat

10 Linear AnalysisLinear Combination of SUBCASEs using SUBCASE IDs

Linear Combination of SUBCASEs using SUBCASE IDs

IntroIn MSCestabliscoefficcombincoefficare largSUBSE

BeneThe effpractic

UserLinear control

Case CSeethe

Gives t

Forma

SUBSE

ExampSUBSE

SUB

DescS0SnSUBnduction Nastran, linear combination of SUBCASEs can be done with SUBCOM and SUBSEQ where SUBCOM hes a delimiter in case control and SUBSEQ is used to provide coefficients for each SUBCASEs involved. The ients on SUBSEQ are positional with respect to number of previously defined SUBCASEs. In the scenario of ing 1st and last SUBCASEs of 100 SUBCASEs, SUBCOM will have 100 coefficients with only the 1st and last ients are non-zero. It can be a tedious and error pronged process to prepare SUBCOM/SUBSEQ when there e number of SUBCASEs. To alleviate the effort needed to prepare input for linear combination of SUBCASEs, Q1 is introduced and SUBCASE IDs are used along with the coefficients.

fitsort needed to prepare the input for linear combination of SUBCASEs has been reduced. In addition, there is ally no limit on the number of coefficients allowed on SUBSEQ1.

Interfacecombination of SUBCASEs with SUBCASE IDs is implemented with the introduction of SUBSEQ1 MPC case command.

ontrol SUBSEQ1 (Case) (p. 538) in the MSC Nastran Quick Reference Guide for the full description.

he factors for linear combination of a specific group of SUBCASEs.

t:

Q1= s0, s1, sub1, s2, sub2, [sn, subn]

le:Q1= 1.0, 1.0, 101, -1.0, 102

SEQ1 (Case) Subcase Factors for Combination

riber MeaningFactor for all SUBCASEs involved. (No default; Real0.).Factor applicable to SUBn only (Real; No default).SUBCASE ID (No default; Integer>0).

11Linear AnalysisLinear Combination of SUBCASEs using SUBCASE IDs

Remarks:1. The SUBSEQ1 command can only appear after a SUBCOM command.2. SUBSEQ1 may only be used in SOL 101 (Statics) or SOL 144 (Static Aeroelasticity) and in SOL 200 with

3.4.

TestThe folinstalla

ANALYSIS=STATIC or ANALYSIS=SAERO.SUBSEQ1 and SUBSEQ are mutually exclusive and can't both appear under a SUBCOM.S0, S1 and SUB1are required input for SUBSEQ1. S2,SUB2 to Sn,SUBn pair are optional.

Caseslowing test decks are available in the msc20140/nast/tpl/intload subdirectory of MSC Nastran tion directory.

sseq1.datsseq2.datsseq3.dat

12 Linear AnalysisFatigue Analysis of Spot Welds

Fatigue Analysis of Spot Welds

IntroIn addicapabilmethodvarious

The spo

Bar ElFatiguebar elemrespect

Weld ECWELthese elbottom

Solid A morethe top relativeductiontion to standard stress-life (S-N) and strain-life (-N) fatigue analysis capabilities, MSC Nastran now has the ity of determining the fatigue life of spot welds. The capability is a specialized version of the standard S-N ology where the forces from the spot welds are converted to structural stresses and fatigue life determined at angles around the circumference of the spot weld.

t welds themselves can be modeled using three different modeling technique:

ements analysis of spots welds was originally developed using stiff bar or beam (CBAR/CBEAM).elements. Single ents are placed at the weld locations and each end of the elements connects to the top and bottom metal sheets,

ively.

lementsD elements can also be used to model the spot weld in the same way as CBAR elements. The benefit of using ements over CBAR elements is simple the fact that the modeling becomes easier in that the mesh of the top and sheets do not have to line up to keep the bar elements perpendicular to the sheets.

Elements recent technique is the usage of a single solid (CHEXA) element connected using rigid (RBE3) elements to and bottom sheets as shown below. Again, this has the advantage of allowing the element to be placed anywhere to the mesh.

13Linear AnalysisFatigue Analysis of Spot Welds

The grid point forces from the solid element are transformed to give equivalent forces as those extracted from the bar and weld element methods and the fatigue life procedure proceeds in exactly the same way from that point.

For fullthe MS

BeneAll the

The maNastranas far asheets tcombin

Criticalwelds i details of the modeling guidelines, usage, theory, methodologies, and for a tutorial see Spot Welds (p. 237) in C Nastran Fatigue Analysis Users Guide.

fits benefits of standard fatigue analysis with MSC Nastran are now realized for fatigue analysis of spot welds.

in benefit is simply the ability to compute fatigue life and criticality of spot welds directly within the MSC analysis quickly and efficiently. Certain element types used to simulate the spot welds may give better benefits

modeling ease is concerned. For example, using stiff CBAR elements requires that mesh of the top and bottom o align properly at the spot weld connection points. Using a CWELD element or the CHEXA/RBE3 ation as outlined above, reduces this burden as the alignment is not critical when using these modeling methods.

locations can be easily identified using a postprocessor such as Patran. Here an automotive part with many spot s displayed where the critical fatigue life of each spot weld is shown as a color-coded sphere.


User InterfaceThis feature is invoked through the FTGDEF and FTGPARM bulk data entries by supplying a SPOTW line with correspentry isMATFTidentify

Case CA FATIcase cocontrol

Bulk D

FormaThe linpropert:

ExampThis exwith itsare def

FTG

1FTGD

FTGDonding parameters defining the spot weld locations, spot weld parameters, respectively. The PFTG bulk data used to supply sheet thickness and weld diameter information for each group of defined spot welds. The G entry is used to supply specific spot weld S-N material data. SET1, SET3, and SET4 entries can be used to the elements to be treated as spot welds.

ontrol GUE case control must be specified in order for any fatigue analysis to occur in MSC Nastran. The FATIGUE ntrol activates the FTGDEF and FTGPARM entries of the same ID as that called out on the FATIGUE case .

ata Entry

t:e and fields of the FTGDEF entry highlighted below are new and define the spot weld elements and associated ies. See FTGDEF (p. 2052) in the MSC Nastran Quick Reference Guide for more details.

le:ample defines three (3) sets of spot weld elements by referencing SET4 IDs 44, 45, and 46. Each is associated own property set defined by referenced PFTG IDs 1, 2, and 3, respectively. The actual elements themselves ined in the SET4 entries.

DEF Fatigue Element Definitions

2 3 4 5 6 7 8 9 10EF ID TOPSTR PFTGID TOPDMG

ELSETSPOTW

ELSID1 PFTGID1 ELSID2 PFTGID2 ELSID3 PFTGID3ELSID4 PFTGID4 ... ... ... ...

-etc.-SEAMW

XELSET

EF 42SPOTW 44 1 45 2 46 3


Remar1.

FormaThe SEfor the :

ExampThis ex

Remar1.

Describer MeaningTOPS

TOPD

SET4

1SET

SET

DescTYPEks:A SPOTW line must exist in order for element to be treated as spot welds. If the FTGDEF entry is absent or the SPOTW line is missing, a standard fatigue analysis is assumed. This makes the FTGDEF entry required for fatigue analysis of spot welds.

t:T4 entrys TYPE field has been modified to allow PBAR, PBEAM, and PWELD property sets to be specified identification of spot welds. These SET4 entries are referenced by the FTGDEF entry on the SPOTW line.

le:ample defines all elements associated to PWELD property IDs 44 and 45 as part of the element set.

ks:See SET4 (p. 3497) in the MSC Nastran Quick Reference Guide for more detail.

TR Top stress percentage. Only elements with combined stress in this top percentage will be retained and report results. (0.0 < Real 100.0; Default = blank - 100% will be used). Should not be used with SOL 200 or for fatigue analysis of spot and seam welds; leave blank.

MG Top damage percentage. Only elements with damage in this top percentage will be retained and report results. (0.0 < Real 100.0; Default = blank). Should not be used with SOL 200 or for fatigue analysis of spot and seam welds; leave blank.

Property Set Definition

2 3 4 5 6 7 8 9 104 ID CLASS TYPE ID1 ID2 ID3 ID4 ID5

ID6 ID7 ID8 -etc.-

4 10 PROP PWELD 44 45

riber MeaningProperty type. Valid options are PSOLID, PSHELL, PSHEAR, PBAR, PBEAM, and PWELD.


FormaThe PFdiamet:

ExampThis ex

Rema1.

2.

PFTG Fatigue Properties

1PFTG

PFT

DescDIAM

T1/T2

SPTFLt:TG entry has been updated to allow definition of the top and bottom sheet thickness and the spot weld nugget er as highlighted below. See PFTG (p. 3189) in the MSC Nastran Quick Reference Guide for more detail.

le:ample defines the top and bottom sheet thickness to be 1.2 mm and the spot weld diameter to be 5.6mm.

rks:If T1, T2, and DIAM are specifically supplied, they are used directly in the fatigue analysis of spot welds. If either T1 or T2 are blank, the thicknesses are automatically determined from the PSHELL entries that connect the spot welds. If DIAM is left blank, the diameter is derived based on the minimum thickness of the two sheets either side of the weld by performing a lookup on a table.

2 3 4 5 6 7 8 9 10 ID LAYER FINISH KFINISH KF SCALE OFFSET

SHAPE KTREAT DIAM T1 T2 SPTFLG

G 421.2 1.2 5.6 0

riber MeaningSpot weld nugget diameter. Used in the fatigue analysis of spot welds only. (Real > 0.0 or blank, No Default).Top (T1) and bottom (T2) thickness of shells connecting spot welds. Used in the fatigue analysis of spot welds only. (Real > 0.0 or blank, No Default). Both should be left blank if either one is left blank.

G Flag to indicate that a lookup table is to be used to define the spot weld nugget diameter. 0 or 1, Default = 0, no lookup). Only used if CWELD elements are used to define spot welds.


FormaThe linof spot:

ExampThis exthe circ

FTGPARM Fatigue Parameters

1FTGPAR

FTGPA

DescSPOT

Nt:e and fields of the FTGPARM entry highlighted below are new and define the parameters for a fatigue analysis welds.

le:ample defines SIMPLE mean stress correction method and 18 angles to be used to calculate fatigue life around umference of the spot welds and to report only the critical location.

2 3 4 5 6 7 8 9 10M ID TYPE FACTOR NTHRD LOGLVL

STRESSor

STRAIN

... ... ... ... ...

RAINFLOW ... ... ...CERTNTY ...

FOS ... ... ... ... ...DAMAGE ... ... ... ...SPOTW COMB CORR NANGLE SWLOC MIDDLE TORSIONSEAMW ... .. ... ... ...MULTI ... ... .. ... ... ... ...

RM 42 SNSPOTW STDRD SIMPLE 18 0 0 0

riber MeaningW Flag indicating that parameters for fatigue analysis of spot welds are to follow.

COMB Stress combination to use in the fatigue analysis. Default=STNDRD, which is basically a critical plane analysis.

CORR Mean stress correction to use in the fatigue analysis of spot welds. Only NONE or SIMPLE are valid for fatigue analysis of spot welds. (Character; Default = NONE).

ANGLE The number of calculation angles in 360 degrees around the spot weld. (10Integer360; Default = 18, i.e., every 20 degrees)

SWLOC Location on the spot welds to report fatigue life. Zero (0) reports worst case angle and location (top/bottom sheet or nugget); one (1) reports worst case angle for each location; two (2) reports worst case location for each angle; three (3) reports all locations and angles. (Integer 0, 1, 2, or 3, Default=0).


Rema1.

FormaThe linanalysi:

ExampThis exweld. Adefined

MIDDLE Whether to process middle sheets if there are more than two sheets in the weld. (Integer 0 or 1,

T

MAT

1MATFT

MATF

Describer Meaningrks:See FTGPARM (p. 2061) in the MSC Nastran Quick Reference Guide for more details.

t:e and fields of the MATFTG entry highlighted below are new and define the material parameters for a fatigue s of spot welds. For full details see MATFTG (p. 2713) in the MSC Nastran Quick Reference Guide.

le:ample defines an S-N curve that will be used for both the top (S1) and bottom (S2) sheets and the nugget of the SIMPLE mean stress correction as called out on the FTGPARM entry requires the MSS parameters to be . All other data that could be entered is defaulted to system defined parameters based on the material code 99.

Default = 0 - do not process middle sheets). ORSION Whether to calculate torsion in the spot weld. (Integer 0 or 1, Default = 0 - do not calculate

torsion).

FTG Fatigue Material Properties

2 3 4 5 6 7 8 9 10G MID CNVRT

STATIC YS UTS CODESN

SNS1SNS2

SRI1 b1 Nc1 b2 Nfc SE BTHRESH

M1 M2 M3 M4 MSS RTHICK nTHICK

SF-FXY DE-FXY TE-FXY SF-MXY DE-MXY TE-MXYSF-FZ DE-FZ TE-FZ SF-MZ DE-MZ TE-MZ

TABLE ... ... ... ... ... ...BASTEN ... ... ... ... ...

EN ... .. ... ... ... ... ...MATID ... ... .. ... ... ... ...

TG 42 1.0STATIC 682.0 99SNS1 3095.0 -0.1339 1.0e8 0.0 1.0e30 0.1

0.4


Remar1.

2.

3.

TestFollowdirectoUsers

Describer MeaningSNSNS1SNS2

kangkangkangkangkangkangkangshochoriverttorqks:All three S-N curves may be defined, one for the top and bottom sheets each (SNS1, SNS2) and one for the spot weld nugget (SN). If any of these are missing, special rules are used to determine which S-N curve is associated to which spot weld location.If no S-N curve data is supplied and only the STATIC line is present, then defaults parameters based on the material CODE are used. See MATFTG (p. 2713) in the MSC Nastran Quick Reference Guide for full details.

Casesing test decks are available in the msc20140/nast/tpl/nef_ug subdirectory of MSC Nastran installation ry. These decks are also used as part of the tutorial in Spot Welds (p. 237) in the MSC Nastran Fatigue Analysis Guide.

Flag indicating the definition of an S-N curve(s) follow (Character = SN, optional).

MSS Mean stress sensitivity factor, used only for fatigue analysis of spot welds with CORR=SIMPLE on the FTGPARM entry. (0.0 Real 1.0, Default=blank). This mean stress correction method is a simplified version of the FKM method where M1=M2=M3=M4=-MSS.

SF-*DE-*TE-*

Scale factors, diameter and thickness exponents for stress due to FX or FY (shear forces), MX or MY (bending moments), FZ (axial force), and MZ (torsion), respectively (Real, Default = blank) used in fatigue analysis of spot welds only.

Input File Description_cbar.dat Single spot weld model using CBAR element._chexa.dat Single spot weld model using CHEXA/RBE3 elements._cw_aln.dat Single spot weld model using CWELD element with ALIGN option._cw_eid.dat Single spot weld model using CWELD element with ELEMID option._cw_ep.dat Single spot weld model using CWELD element with ELPAT option._cw_gid.dat Single spot weld model using CWELD element with GRIDID option._cw_pp.dat Single spot weld model using CWELD element with PARTPAT option.ktowerSPOT.datzontal.dacical.dacue.dac

Shock Tower model with fatigue analysis of spot welds using bar elements and corresponding DAC files defining the cyclic load variation for the three subcases contained in the analysis deck.

20 Linear AnalysisFatigue Analysis of Seam Welds

Fatigue Analysis of Seam Welds

IntroIn addicapabilmethod

The seaportionare incl

The thrtypicalthroat, weld. Gdevelop

Below ductiontion to standard stress-life (S-N) and strain-life (-N) fatigue analysis capabilities, MSC Nastran now has the ity of determining the fatigue life of seam welds. The capability is a specialized version of the standard S-N ology.

m welds themselves are modeled using standard shell elements (normally CQUAD4s). There are three (3) s of most seam welds designated as the root, the toe, and the throat. Only these elements or portions of them uded in a fatigue analysis of seam welds.

oat is the actual weld itself and the root and toe are designated as the elements that weld connects. Below is a model showing a seam weld connection two rectangular tubes at right angles. The yellow elements are the the magenta elements are the toe, and the bluish elements are the root. This seam weld type is known as a fillet enerally only the root or toe elements are analyzed for fatigue as fatigue cracks of seam welds usually only at the interface on the top (Z2) side of the shell elements closest to the weld.

are graphics of the supported weld types and the locations of the toe, root, and throat.

21Linear AnalysisFatigue Analysis of Seam Welds

Fillet Welds

Overla

Laser O

Laser Ep Welds

verlap Welds

dge Overlap


Generic Seam Welds

For fulin the M

BeneAll the

The maNastranthe sea

UserThis fecorrespused tol details of the modeling guidelines, usage, theory, methodologies, and for a tutorial see Seam Welds (p. 263) SC Nastran Fatigue Analysis Users Guide.

fits benefits of standard fatigue analysis with MSC Nastran are now realized for fatigue analysis of seam welds.

in benefit is simply the ability to compute fatigue life and criticality of seam welds directly within the MSC analysis quickly and efficiently. Here is a zoomed in plot of fatigue life of only the toe and root elements along

m line nodes only of the throat elements (not shown).

Interfaceature is invoked through the FTGDEF and FTGPARM bulk data entries by supplying a SEAMW line with onding parameters defining the seam weld locations, spot and parameters, respectively. The MATFTG entry is supply specific seam weld S-N material data.


Case Control A FATIGUE case control must be specified in order for any fatigue analysis to occur in MSC Nastran. The FATIGUE case control activates the FTGDEF and FTGPARM entries of the same ID as that called out on the FATIGUE case control

Bulk D

FormaThe linpropert:

ExampThis exthe elemPFTG Iare defithus eli

FTG

1FTGD

FTGD

DescSEAM.

ata Entry

t:e and fields of the FTGDEF entry highlighted below are new and define the seam weld elements and associated ies. See FTGDEF (p. 2052) in the MSC Nastran Quick Reference Guide for more details.

le:ample defines toe and root elements of a fillet seam weld by referencing SET1 IDs 44 and 45, each containing ents that make up that portion of the weld. Each is associated with its own property set defined by referenced

Ds 1 and 2, respectively. In addition to identifying the elements themselves, an additional SET1 IDs 54 and 55 ned containing only the nodes along the seam line of the elements that connect to the throat (seam weld itself), minating from the analysis all those nodes of the elements away from the seam weld itself.



ELSET ... ... ... ... ... ...SPOTW ... ... ... ... ... ...SEAMW ELSID1 PFTGID1 NDSID1 WELD1 TYPE1

ELSIDE2 PFTGID2 NDSID2 WELD2 TYPE2-etc.-

XELSET

EF 42SEAMW 44 1 54 FILLET TOE

45 2 55 FILLET ROOT

riber MeaningW Flag indicating that a list of element set and property pairs will follow, defining the elements and

their associated properties for fatigue analysis of seam welds.ELSIDi Same as ELSIDi under ELSET above. These are to elements that make up the seam weld toe, root,

or throat.


Rema1.

2.

PFTGIDi Same as PFTGIDi under ELSET above. Reference to PFTG entries that contain the element Describer Meaningrks:A SEAMW line must exist in order for element to be treated as seam welds. If the FTGDEF entry is absent or the SEAMW line is missing, a standard fatigue analysis is assumed. This makes the FTGDEF entry required for fatigue analysis of seam welds.The normals of the throat elements should point outward toward the welder, except for laser overlap, in which case the normals just need to be consistently the same direction. The elements defining the toe and root of the weld must have the top of the shell (Z2 layer) be the side where the crack is expected to develop. For full descriptions of the throat, root, and toe elements for the various seam welds, please see Seam Welds (p. 263) in the MSC Nastran Fatigue Analysis Users Guide, which show proper modeling techniques. The WELDi and TYPEi entries are used for labeling purposes only and have no effect on internal calculations.

fatigue properties for this set of elements.NDSIDi ID of a SET1 or SET3 entry listing grids of the elements defined by ELSIDi to be retained in the

analysis. These grids define the seam line of the seam weld. If left blank, all nodes of the elements are retained. Nodes defined that are not part of ELSIDi are ignored. (Optional, Integer >0).

WELDi Seam weld definition. One of the following: FILLET, OVERLAP, LASER, EDGE, or GENERIC, which define either a fillet, overlap, laser overlap, laser edge overlap or generic seam weld, respectively. (Character; Default=GENERIC).

TYPEi The type location on the seam weld that this set of elements represent. One of the following: TOE, ROOT, or THROAT. (Character; Default = TOE for all but WELDi = LASER where Default = ROOT).


FormaThe linof seam:

ExampThis ex

FTGPARM Fatigue Parameters

1FTGPAR

FTGPA

DescSEAMt:e and fields of the FTGPARM entry highlighted below are new and define the parameters for a fatigue analysis welds.

le:ample defines FKM mean stress correction method and default settings for the rest of the parameters.


STRESSor

STRAIN

... ... ... ... ...


FOS ... ... ... ... ...DAMAGE ... ... ... ...

SPOTW ... ... .. ... ... ...SEAMW COMB CORR THICK LOCSM RESENTMULTI ... ... .. ... ... ... ...

RM 42 SNSEAMS FKM

riber MeaningW Flag indicating that parameters for fatigue analysis of seam welds are to follow. See Remark 9.

COMB Stress/strain combination to use in the fatigue analysis of seam welds. Only ABSMAXPR and CRITICAL are supported. (Character; Default = ABSMAXPR).

CORR Mean stress correction to use in the fatigue analysis of seam welds. Only NONE or FKM are valid for fatigue analysis of seam welds. (Character; Default=NONE).

THICK Thickness correction to be applied. (Integer 0 or 1; Default =0 - no correction)LOCSM Location on seam weld to report life. Valid values are "NODE, SGAGE, CORNER,

BILIN, or CUBIC (Character; Default = NODE). If STRESS line is also include, LOCSM must be the same as LOC. LOC=ELEM is not valid for fatigue analysis of seam welds and cannot be mixed with LOC = NODE.

RESENT Result entity type used in the fatigue analysis of seam welds; only STRESS is currently supported. (Character; Default = STRESS).


Remarks:1. See FTGPARM (p. 2061) in the MSC Nastran Quick Reference Guide for more details.

FormaThe linanalysi:

ExampThis exmean sdefinedparame

MAT

1MATFT

MATF

DescSNSNBRSNBR

Bt:e and fields of the MATFTG entry highlighted below are new and define the material parameters for a fatigue s of seam welds. For full details see MATFTG (p. 2713) in the MSC Nastran Quick Reference Guide.

le:ample defines an S-N curve that will be used for both the flexible (BR1) and stiff (BR0) definitions. An FKM tress correction as called out on the FTGPARM entry requires at least some of the M1-M4 parameters to be unless on ly the STATIC line is supplied. All other data that could be entered is defaulted to system defined ters based on the material code 99.


2 3 4 5 6 7 8 9 10G MID CNVRT

STATIC YS UTS CODESN

SNBR1SNBR0

SRI1 b1 Nc1 b2 Nfc SE BTHRESH

M1 M2 M3 M4 MSS RTHICK nTHICK

TABLE ... ... ... ... ... ...BASTEN ... ... ... ... ...

EN ... .. ... ... ... ... ...MATID ... ... .. ... ... ... ...

TG 42 1.0STATIC 682.0 99SNBR1 3095.0 -0.1339 1.0e8 0.0 1.0e30 0.1

-0.4 -0.4

riber Meaning

10

Flag indicating the definition of an S-N curve(s) follow (Character = SN, optional).

THRESH Threshold value of the bending (r) ratio used in interpolation between stiff and flexible SN curves for fatigue analysis of seam welds. (0.0 Real 0.999; Default=0.5)


Remar1.

2.

3.

TestFollowdirectoUsers

RTHICK Reference thickness/threshold (in consistent model length units) for sheet thickness correction

tee_

Describer Meaningks:Both S-N curves may be defined, one each for the flexible (BR1) and stiff (BR0) definitions (SNBR1, SNBR0). If either of these are missing, special rules are used to determine which S-N curve to use.If no S-N curve data is supplied and only the STATIC line is present, then defaults parameters based on the material CODE are used. See MATFTG (p. 2713) in the MSC Nastran Quick Reference Guide for full details.

Caseing test deck is available in the msc20140/nast/tpl/nef_ug subdirectory of MSC Nastran installation ry. This deck is also used as part of the tutorial in Spot Welds (p. 237) in the MSC Nastran Fatigue Analysis Guide.

used in fatigue analysis of seam welds. Ignored if THICK=0 on the FTGPARM entry for SEAMW. Must be supplied if THICK=1. (Real 1.0e-9; No Default)

nTHICK Sheet thickness correction exponent used in the fatigue analysis of seam welds. Ignored if THICK=0 on the FTGPARM entry for SEAMW. Must be supplied if THICK=1. (Real; No Default)

Input File Descriptiontube.dat Fillet seam weld model using CQUAD element.

28 Linear AnalysisUse of RPC Files in Fatigue Analysis

Use of RPC Files in Fatigue Analysis

IntroTo defiallows this infexterna

In manin an inextensinormalpoints wchanneto these

BeneConsolfiles. Kin keep

User

Bulk D

FormaA new of RPC

FTG

1FTGLOductionne the cyclic variation in the loading needed for fatigue analysis using the pseudo-static method, MSC Nastran the user to define a table (TABLFTG or TABLED1 entries) or to define an external (DAC formatted) file with ormation. Each load that needs a cyclic variation definition must be associated with one of these tables or l files.

y instances these cyclic load definitions are acquired from test data or other simulation techniques and stored dustry standard file type called an RPC or RPC3 (remote parameter control) file, which normally has the file on of .rsp. These files contain all the data for all the loads from a given structure separated into what are ly called channels. For example, road load data on an automobile might be collected from the four load input

here the wheels contact the ground. There would then be four channels of data. Or there could be 4x3=12 ls of data for the three component directions at each of the four input locations. It is convenient to refer directly files and the appropriate channel number rather than specifying individual files or creating individual tables.

fitsidating large amounts of data into a single file to help with data management is the largest benefit of using RPC eeping that data in those files and directly accessing the data from the MSC Nastran job is of utmost importance ing the engineers job easy and simple.

Interface

ata Entry

t:and modified field as highlighted below have been added to the FTGLOAD entry to accommodate the reference entries as shown here.

LOAD Fatigue Loading Time Variation

2 3 4 5 6 7 8 9 10AD ID TID LCID LDM SCALE/

MAXOFFSET/

MINTYPE CHNL

UNITS EQUIV EQNAME

29Linear AnalysisUse of RPC Files in Fatigue Analysis

Example:This defines FTGLOAD entry of ID 42 and indicates that an RPC type file is referenced where channel 10 is the channel to use for the definition of the cyclic loading. The TID field references the UDID of a UDNAME entry that contain

Remar1.

2.

3.4.

TestFollowdirecto

FTGLO

DescID

TYPE

CHNL

shocevenevenevens the name of the actual RPC file.

ks:CHNL is only used for TYPE=RPC. If supplied, the specified channel of the referenced RPC file is used. If it is left blank, the next available channel sequentially from the last one referenced will be used. For example, if there are three FTGLOAD entries for a specific event and CHNL is blank for all three, the 1st one will use channel 1, the 2nd one will use channel 2 and the 3rd will used channel 3. If in this example the 1st specifies CHNL=11 and the others are blank, then the channels used will be 11, 12, and 13. If the 1st is left blank and the 2nd references CHNL=12, then the channels used will be 1, 12, and 13.The same RPC file must be referenced for all loads of any given load event (i.e., all the referenced FTGLOAD entries on a FTGEVNT entry).It is not allowable to mix usage of DAC and RPC files or usage of TABLFTG and RPC files.See FTGLOAD (p. 2058) in the MSC Nastran Quick Reference Guide for full details. Also see A Simple Duty Cycle (p. 169) in the MSC Nastran Fatigue Analysis Users Guide for an example of usage.

Caseing test deck is available in the msc20140/nast/tpl/nef_ug subdirectory of MSC Nastran installation ry.

AD 42 99 1 1.0 1.0 0.0 RPC 10UNITS 5.0 Laps

riber MeaningUnique ID which is referenced by a FTGEVNT entry or directly by a FATIGUE case control (Integer > 0).

Flag indicating the type of load being defined. Values can be blank, "DB", "DAC", "RPC" CONST or "STATIC". Default is blank.Channel of referenced RPC file (TYPE=RPC). (Integer >0, Default is blank).

Input File DescriptionktowerDCY_v4.dat Duty Cycle job that uses RPC3 files instead of DAC files.t_a.rspt_b.rspt_c.rsp

External RPC3 formatted files describing the cyclic load variation of the load input, each containing the loads for its individual event in the form of channel data.

30 Linear AnalysisBlock Loading in Fatigue Analysis

Block Loading in Fatigue Analysis

IntroMany tconstantable de

When mdefine duty cy

BeneThis feincreas

Less daTABLEthese enumbe

Becausif a dut

User

Bulk D

FormaFields aamplitu

FTG

1FTGLOductionimes the cyclic loading definition for fatigue analysis using the pseudo-static method requires only very simple t amplitude definitions. The ability to define a cyclic load application without reference to an external file or finition is accomplished using the CONST keyword on the TYPE field of the FTGLOAD entry.

any constant amplitude signals of multiple simultaneously loaded input locations are combined together to various load events, and those events are strung together to form an overall load sequence (sometimes called a cle), this is referred to as block loading.

fitsature has both the benefit of consolidating the amount of data needed to define such block loading and of ed performance gains.

ta is required than the original method of defining a cyclic load variation through the use of TABLFTG or D1 entry. Every load with a different constant amplitude requires a separate cyclic load definition via one of

ntries in previous releases. Now the variation is defined directly on the FTGLOAD entry, thus reducing the r of entries needed by up to 50% in many cases.

e there are less cards to process, the throughput is much faster, sometimes by an order of magnitude, especially y cycle is defined.

Interface

ata Entry

t:s highlighted below have been modified on the FTGLOAD entry to accommodate the definition of constant de (block) loading as shown here.

LOAD Fatigue Loading Time Variation

2 3 4 5 6 7 8 9 10AD ID TID LCID LDM SCALE/

MAXOFFSET/

MINTYPE CHNL

UNITS EQUIV EQNAME

31Linear AnalysisBlock Loading in Fatigue Analysis

Example:This defines FTGLOAD entry of ID 42 and indicates that an CONSTant amplitude cyclic loading that varies from 100 to -50 units is defined. The TID field should be left blank as it is not needed anymore to reference any external file or MSC N

Remar1.2.

TestFollowdirecto

FTGLO

DescID

SCAL

OFFS

TYPE

keyhastran table entry.

ks:It is not allowable to mix usage of CONST with any other type of loading.See FTGLOAD (p. 2058) in the MSC Nastran Quick Reference Guide for full details.

Caseing test deck is available in the msc20140/nast/tpl/nef3 subdirectory of MSC Nastran installation ry.

AD 42 1 1.0 100.0 -50.0 CONSTUNITS 5.0 Laps

riber MeaningUnique ID which is referenced by a FTGEVNT entry or directly by a FATIGUE case control (Integer > 0).

E/ MAX Scale factor applied to the load time history (Real, default=1.0). Or the peak amplitude of a constant amplitude signal if TYPE=CONTS (MIN

32 Linear AnalysisMAT1 References on MATFTG Entry

MAT1 References on MATFTG Entry

IntroIn ordefatigueMATFTin the amateriafatigueassociathere ar

To oveentries Referen

BeneObvioudeck. Aand qui

User

Bulk D

FormaA new entries

MAT

1MATFductionr to run a fatigue analysis within MSC Nastran, a MATFTG entry is required. The MATFTG entry defines the material properties and must be linked or associated with existing MAT1 entries. In previous releases all G entries require the same MID (material ID) as their corresponding MAT1 entries, otherwise they are ignored

nalysis and possibly could cause a fatal error to occur if the fatigue analysis can not find associate fatigue l properties. This proves cumbersome for models where many MAT1 entries exist, but could share the same material properties. This forces the duplication of fatigue material properties in order to have all MAT1 entries ted to a proper MATFTG entry. In other words, in previous releases, as many MATFTG entries are required as e MAT1 entries even though the data may be the same in all of them.

rcome this limitation, the MATFTG entry has a new line (keyword) that allows the association of many MAT1 directly on the MATFTG entry. For full details please see MATFTG (p. 2713) in the MSC Nastran Quick ce Guide

fitssly this feature has the benefit of significantly reducing the amount of data needed in the MSC Nastran input nd by allowing multiple MAT1 entries to be associated to a single MATFTG entry, input decks can more easily ckly be modified to add or remove associations.

Interface

ata Entry

t:line highlighted below has been added to the MATFTG entry to accommodate the reference of multiple MAT1 as shown here.


2 3 4 5 6 7 8 9 10TG MID CNVRT

STATIC ...:SN ...

TABLE ...BASTEN ...

EN ...

33Linear AnalysisMAT1 References on MATFTG Entry

ExampThis de10 and

Remar1.

2.

3.

MATID

E NUMID1 MID2 MID3 MID4 MID5 MID6 MID7

MATF

DescMATIle:fines MATFTG entry of ID 42 and associates the generated fatigue material properties defined to MAT1 entries 20.

ks:Element properties must reference MAT1 entries in order to be linked to a MATFTG entry as only metal fatigue analysis of isotropic materials is supported. The MID must match that of an existing MAT1 entry called out by the property entry (e.g. PSHELL) unless the MATID line is provided, in which case all the MIDi referenced on the MATID line are then linked to the MATFTG entry. When the MATID line is used, E and NU must be provided, otherwise Youngs Modulus (E) and elastic Poissons ratio (NU) are extracted from the corresponding MAT1 entry. If the MATID line is used, and a MAT1 of the same ID also exists, that MAT1 ID must be in the MIDi list or it will be ignored in the analysis. In other words, when the MATID line is used, only the supplied MIDi IDs are used in the fatigue analysis.

-etc.-

TG 42 1.0STATIC 430 682 99MATID 2.1e5 0.3

10 20

riber MeaningD Flag indicating that a list of MAT1 IDs is to follow.

E Youngs modulus. (Valid range equivalent in MPa: 2.0e4 Real 3.0e5, no Default).NU Elastic Poissons ratio. (0.25 Real 0.35, Default = 0.3)

MIDi IDs of existing MAT1 entries to which this MATFTG entry will be linked. At least one ID must be supplied. The THRU keyword is not supported.

34 Linear AnalysisMAT1 References on MATFTG Entry

Test CasesFollowing test decks are available in the msc20140/nast/tpl/nef3 subdirectory of MSC Nastran installation directo

sae_

shoc

tee_ry.

Input File Descriptionshaft_MATID.dat Standard SN analysis of the SAE Shaft model with an extreme case of

using a separate MAT1 entry for each element in the model such that the MATFTG entry can use the MATID line to reference all MAT1 entries.

ktower_MATID.dat The Shock Tower spot weld model, with a MAT1 entry for each element analyzed such that the MATFTG entry can use the MATID line to reference all MAT1 entries.

tube_MATID.dat The Tee Tube seam weld model, with a MAT1 entry for each element analyzed such that the MATFTG entry can use the MATID line to reference all MAT1 entries.

35Linear Analysis2-Pass and 3-Pass Fatigue Analysis

2-Pass and 3-Pass Fatigue Analysis

IntroA partion a larfatigueTOPDMand Tip

Here ar

1-PassThis is populat

2-PassIf TOPdetermFTGPAentitiesfully po

2-PassIf TOP(1st) patime hientry. Tis absenhistorieductioncularly useful mechanism for enhancing the performance of a job and more quickly identifying critical locations ge model without compromising the accuracy of the final results is by using the so-called 2-pass or 3-pass analysis techniques. These are activated on the FTGDEF entry by specifying values in the TOPSTR and

G fields. More information can be found in FTGDEF (p. 2052) in the MSC Nastran Quick Reference Guide s for Enhancing Performance (p. 74) in the MSC Nastran Fatigue Analysis Users Guide.

TOPSTR defines the top percentage of entities to be retained in the analysis based on the static stress parameter (von Mises, Absolute Maximum Principal, etc.) and the maximum/minimum (range) of the combined time histories. By default, all entities are retained (100%).TOPDMG defines the top percentage of entities to be retained in the analysis based on calculated damage using a set of reduced (compressed) time histories. This process uses the RAINFLOW options on the FTGPARM entry automatically (defaults used if not present) and then reruns the specified percentage of top damaged entities with the fully populated time histories to give accurate results on the retained entities.

e the likely scenarios:

Analysis - no TOPSTR/TOPDMG specifieddone where neither TOPSTR or TOPDMG are specified. All elements of the analysis are retained and fully ed time histories are used in a single pass. This is the default scenario.

Analysis - TOPSTR onlySTR is used alone (TOPDMG is left unspecified), then a 2-pass analysis is performed where the first (1st) pass ines the entities with the highest combined stress based on the stress combination (COMB field on the RM entry) and the largest stress range of the combined loading time histories. The specified percentage of those is retained for the next pass. The second (2nd) pass performs the fatigue analysis on the remaining entities using pulated time histories.

Analysis - TOPDMG onlyDMG is used alone (TOPSTR is left unspecified or is 100%), then a 2-pass analysis is performed where the first ss determines the percentage of entities to retain based on damage due to a reduced set of time histories. The story reduction/compression is done based on the settings of the RAINFLOW parameters on the FTGPARM he default is RTYPE=LOAD with PCTRD=50% if the FTGPARM entry is not present or the RAINFLOW line t. The second (2nd) pass performs the fatigue analysis on the remaining entities using fully populated time s.

36 Linear Analysis2-Pass and 3-Pass Fatigue Analysis

3-Pass Analysis - TOPSTR and TOPDMG specifiedIf TOPSTR and TOPDMG are both specified, then a 3-pass analysis is performed where the first (1st) pass determines the percentage of entities to retained based on TOPSTR as described above. This eliminates the first set of entities. The secondthird (3

BeneThe usethe ana

As an estressedthe tophistorie

Below processhistoryare nor (2nd) pass eliminates a percentage of the remaining entities from the first (1st) pass based on TOPDMG. The rd) pass then reruns the analysis on the retained entities using the fully populated time histories.

fits of TOSTR and/or TOPDMG allows the user to perform a 2-pass or a 3-pass fatigue analysis run to speed up

lysis time and quickly identify critical locations of the model.

xample if TOPSTR is set to 10 and the model has 1000 entities (GRIDs), then the top 100 (10% or 1000) highly GRIDs are retained for the second (2nd) pass. If TOPDMG is also set to 10%, then of the remaining GRIDs,

10 (10% of 100) most damaged GRIDs are retained for the third (3rd) pass with the fully populated time s. Only the result of those remaining 10 GRIDs are reported.

is a graphic of some 1-pass, 2-pass, and 3-pass performance statistics using 1, 2, 3, and 4 threads on a multi-or Windows machine. The model is of relatively small size (19,000 nodes and 22,000 elements) with two time loads of 3500 points each. Both the total time of the run and the fatigue process itself are shown. The results malized with respect to a 1-pass analysis using a single thread.


User InterfaceThis feature is invoked through the FTGDEF bulk data entry by supplying percentage of entities to retain in the analysithe tim

Case CA FATIcase co

Bulk D

FormaThe tw

ExampThis exfirst pareducedtime hi

FTG

1FTGD

FTGD

DescTOPS

TOPDs in the TOPSTR and TOPDMG fields. Also the settings in the RAINFLOW line of the FTGPARM entry effect e history compression invoked when TOPDMG is used.

ontrol GUE case control must be specified in order for any fatigue analysis to occur in MSC Nastran. The FATIGUE ntrol activates the FTGDEF entry of the same ID as that called out on the FATIGUE case control.

ata Entry

t:o fields highlighted below are new or modified in their behavior in this release for the FTGDEF entry.

le:ample invokes a 3-pass fatigue analysis where 10% of the mostly highly stressed elements are retained in the ss and 10% of the remaining elements are retained based on damage calculated from a second pass with a set of time histories. The third pass then computes damage on the remaining elements with the fully populated

stories.



EF 42 10.0 10.0

riber MeaningTR Top stress percentage. Only elements with combined stress in this top percentage will be retained

and report results. (0.0 < Real 100.0; Default = blank - 100% will be used). Should not be used with SOL 200 or for fatigue analysis of spot and seam welds; leave blank.

MG Top damage percentage. Only elements with damage in this top percentage will be retained and report results. (0.0 < Real 100.0; Default = blank). Should not be used with SOL 200 or for fatigue analysis of spot and seam welds; leave blank.

38 Linear Analysis2-Pass and 3-Pass Fatigue Analysis

Remarks:1. Specifying TOPDMG = 100 actually causes a 2-pass analysis to be performed where the first (1st) pass uses

compressed time histories, but the second (2nd) pass retains 100% of the entities for the analysis using the fully

2.

3.

4.

5.

6.

7.

TestFollowdirecto

sae_sae_sae_sae_sae_sae_sae_sae_sae_sae_sae_sae_populated time histories. This has the effect of decreasing performance rather than increasing. In other words, it makes no sense to use a large percentage for TOPDMG. Leave TOPDMG blank so as not to invoke any additional analysis pass if this not the intent.Neither TOPSTR or TOPDMG can be used for fatigue analysis of spot welds or seam welds or for SOL 200 (optimization) runs. Time history compression is still available however, with the use of RAINFLOW parameters on the FTGPARM entry.Use of TOPDMG will have show little to no increase in performance if the number of points in the time histories is not sufficiently large.Use of RAINFLOW parameter on the FTGPARM entry without specifying TOPDMG does not result in the last pass where the analysis is rerun with fully populated time histories. Results are reported using the compressed time histories.Use of TOPSTS & TOPDMG results in a large performance gain when only using one (1) thread (NTHRD on FTGPARM entry. Diminished benefits are realized with the more treads available.The actual performance benefits show in the fatigue process itself in comparison to the overall time of the Nastran job. The process is highly dependent on model size, input/output considerations, the size and number of time histories, and setting on the RAINFLOW line of the FTGPARM entry.More relative performance benefit from the second (2nd) pass is seen versus the first (1st) pass if more entities are retained from the first (1st) pass, when doing performance comparisons between the different passes.

Casesing test decks are available in the msc20140/nast/tpl/nef3 subdirectory of MSC Nastran installation ry.

Input File Descriptionshaft_1pass_1thread.datshaft_1pass_2thread.datshaft_1pass_3thread.datshaft_1pass_4thread.dat

Single pass analysis using 1, 2, 3, or 4 threads for a multiprocessor machine. No specification of TOPSTR or TOPDMG is made. Fatigue analysis is done on all entities with fully populated time histories. The baseline for comparisons is the single pass, single thread input deck.

shaft_topstr_1thread.datshaft_topstr_2thread.datshaft_topstr_3thread.datshaft_topstr_4thread.dat

2-pass analysis using 1, 2, 3, or 4 threads for a multiprocessor machine. Only TOPSTR is used to retain highly stressed entities for the final pass.

shaft_topdmg_1thread.datshaft_topdmg_2thread.datshaft_topdmg_3thread.datshaft_topdmg_4thread.dat

2-pass analysis using 1, 2, 3, or 4 threads for a multiprocessor machine. Only TOPDMG is used to retain highly damaged entities based on time history compression for the final pass.


sae_shaft_3pass_1thread.datsae_sae_sae_

Full 3-pass analysis using 1, 2, 3, or 4 threads for a multiprocessor

shaft0shaft0

Input File Descriptionshaft_3pass_2thread.datshaft_3pass_3thread.datshaft_3pass_4thread.dat

machine. Both TOPSTR and TOPDMG are used to first retain only the highly stressed entities and from those, retain only the highly damaged entities based on time history compression for the final pass.

1.dac2.dac

Time history files necessary to run any of the above input decks.

40 Linear AnalysisFatigue Analysis with Multiaxial Assessment

Fatigue Analysis with Multiaxial Assessment

IntroIn real in the cdirectiomultiaxuniaxia

Multiax

ductionservice conditions, many structures experience multiaxial loadings in critical locations. That is, the stress state ritical location is characterized as having more than one significant principal stress, and/or the principal stress ns change with time. Methods are available in MSC Nastran for investigating the stress state to assess ial conditions and whether, or not, further investigation and possible corrections are needed based on the l assumptions made by standard stress-life (S-N) or strain-life (-N) fatigue analysis.

ial assessments result in additional output. The most significant results are described here:

Mean Biaxiality Ratio - The mean value of ae during the loading sequence. The biaxiality ratio (ae), is defined as the minor in-plane principal stress divided by the major in-plane principal stress. The value can take on any value between minus one (-1) and one (1). A zero (0) biaxiality ratio indicates only one principal stress, which is a good indicator of a uniaxial stress state.

Angle Range The relative range the angle (p) of the major in-plane principal stress moves during the loading sequence. The smaller the angle range, the more proportional the loading.

Non-proportionality FactorA factor derived from the 2-D in-plane stress tensor components over the duration of the loading sequence that normally takes on values between zero (0) and something less than one (1.0). With this factor in conjunction with the biaxiality ratio, an engineer can make educated decisions about the proportionality of the loading and thus the stress state.

41Linear AnalysisFatigue Analysis with Multiaxial Assessment

BenefitsMultiaxial assessment and biaxiality analysis give the engineer confidence that the stress state in the critical locations of the manalysi

Shouldmultiaxassumpdone? Bcombinproport

The SAthe tutoto boththe moodel are appropriate for the fundamental assumptions of standard stress-life (S-N) or strain-life (-N) fatigue s - that of a predominately uniaxial state of stress.

the stress state assessment show a something other than a uniaxial state, the engineer can then assess the ial stress state and make decisions on the validity of the fatigue analysis, i.e., are the original uniaxial tions valid? does proportional loading have to be taken into account? does a critical plane analysis need to be ased on the multiaxial assessment results, the code can automatically decide to the most appropriate stress

ation parameter to use calculate fatigue damage such as by performing critical plane analysis for non ional loading cases.

E Shaft model is shown below with fatigue life plotted. A multiaxial assessment of this model is the subject of rial in A Multiaxial Assessment (p. 285) in the MSC Nastran Fatigue Analysis Users Guide. The shaft is subject a bending and a torque loading condition, which produces non-proportional loading at the critical locations of del. Subsequent plots show the biaxiality ratio and non-proportionality factor at all locations of the model.

Fatigue Life of SAE Shaft


Biaxiality RatioNon-proportionality Factor


User InterfaceThis feature is invoked through the FTGPARM bulk data entry by supplying requested method of multiaxial assessmQuick R

Case CA FATIcase co

Bulk D

FormaThe linassessm:

ExampThis ex

FTG

1FTGPAR

FTGPAent and any requested parameters. More information can be found in FTGPARM (p. 2061) in the MSC Nastran eference Guide.

ontrol GUE case control must be specified in order for any fatigue analysis to occur in MSC Nastran. The FATIGUE ntrol activates the FTGPARM entry of the same ID as that called out on the FATIGUE case control.

ata Entry

t:e and fields of the FTGPARM entry highlighted below are new and define the parameters for a multiaxial ent.

le:ample requests a SIMPLE biaxiality analysis. All other parameters are defaulted.

PARM Fatigue Parameters


STRESSor

STRAIN

... ... ... ... ...


FOS ... ... ... ... ...DAMAGE ... ... ... ...SPOTW ... ... .. ... ... ...SEAM ... ... .. ... ...

MULTI MMTHD NONLWR NONUPR BIAXLWR BIAXMID BIAXUPR ZEROGATE

RM 42 SN 10.0MULTI SIMPLE


Remar1.

Describer MeaningMULT

NON

BBBks:See FTGPARM (p. 2061) in the MSC Nastran Quick Reference Guide for more details.

I Flag indicating that parameters for biaxial/multiaxial assessment are to follow. MMTHD NONE = No multiaxial assessment is done.

SIMPLE = Calculates simple biaxiality ratios only. STANDard =Standard method of assessment, which merely returns the results of the

assessment. AUTO = Performs the standard method, but then may recalculate fatigue damage

depending on the results of the assessment.NLOWRONUPR

Used only when MMTHD = AUTO. Lower and Upper thresholds used to check if the loading is proportional. This is used in combination with the biaxiality ratio thresholds.NONLWR: (0


Test CasesFollowing test decks are available in the msc20140/nast/tpl/nef_ug subdirectory of MSC Nastran installation directoexampl

sae_sae_sae_notcnotcshaft0shaft0ry. Please see A Multiaxial Assessment (p. 285) in the MSC Nastran Fatigue Analysis Users Guide for an e of usage.

Input File Descriptionshaft_multiax_auto.datshaft_multiax_stnd.datshaft_multiax_simple.dat

SAE Shaft model with bending and torsional loading to produce a multiaxial state of stress at the critical fatigue locations of the model.

h_left.inch_right.inc

Include files of SET1 entries defining the left and right notches of the shaft.

1.dac2.dac

Time history files necessary to run any of the above input decks.

47Linear AnalysisAxisymmetric Harmonic Concentrated Mass Element

Axisymmetric Harmonic Concentrated Mass Element

IntroAxisymCTRIArepresecapabil

AxisThis elentry. grid poreferenfreedomharmon

The fol

The aboaxisym

SamIn ordeconcenconcenductionmetric harmonic elements were introduced in V2013.1. These are elements that are defined via CQUADX and X Bulk Data entries that reference PAXSYMH property entries. These elements are very useful for nting axisymmetric rotors in many practical situations. In the 2014 release we have augmented the previous ity to allow concentrated masses to be used in an axisymmetric harmonic calculation

ymmetric Harmonic Concentrated Mass Element ement has been developed by expanding the definition of the grid point referenced on a CONM2 Bulk Data With this enhancement, the grid point (in Field 3) of a CONM2 entry may reference not only a standard 3-D int, but also a harmonic grid point (that is, a grid point specified on a CQUADX or CTRIAX element cing a PAXSYMH entry). The former type has the standard three translational and three rotational degrees of

while the latter type has three symmetric components and three anti-symmetric components dependent on the ic value.

lowing additional points must be noted with regard to this feature:

For a harmonic grid point, the mass value M specified on the CONM2 entry is the total mass. This value is not to be multiplied by 2. The mass matrix computed for harmonic grids is dependent on the harmonic value associated with the PAXSYMH entry and will be automatically determined by the code.Only harmonic values of 0 and 1 have contributions to grid point weight generator type calculations.Any values specified in the CID, X1, X2, X3, I11, I21, I22, I31, I32, or I33 fields of a CONM2 entry are ignored for a harmonic grid.

ve enhancement will greatly enhance user convenience for modeling many practical configurations involving metric harmonic element rotors.

ple Problemr to demonstrate this feature, an axisymmetric harmonic beam model and a 1D beam model, both with trated masses, were developed as shown in Figure 1: Axisymmetric harmonic and 1D beams with trated mass (CONM2).

48 Linear AnalysisAxisymmetric Harmonic Concentrated Mass Element

Figure

Both ofmass isthe axis

$ CONMCONM2 ---$ CONMCONM2

Since timplemthe bea

1.00010.00000.00000.0000-1.1510.0000

1.1.00010.00000.00000.0000-1.2190.0000

2.2-1 Figure 1: Axisymmetric harmonic and 1D beams with concentrated mass (CONM2)

the beams have similar structural and geometric properties. In the case of the 1D beam, where the concentrated defined on a 3D grid point, both mass and inertia properties for CONM2 need to be specified. In the case of ymmetric harmonic beam, only the total mass needs to be specified for CONM2.

2 on 3D grid point 208 204 0 100.000. 0. 0. 0.50. 0.50. 0.1.02 on axisymmetric harmonic grid point 115 104 0 100.00

he beams have a radius of 0.1 units, the mass and inertia properties of both the beams should be identical if the entation is correct. Here, the results obtained using PARAM GRDPNT about the geometric center of both ms are presented:

a. 1D Beam

57E+02 0.000000E+00 0.000000E+00 0.000000E+00 -1.151965E-19 0.000000E+00 00E+00 1.000157E+02 0.000000E+00 1.151965E-19 0.000000E+00 0.000000E+0000E+00 0.000000E+00 1.000157E+02 0.000000E+00 0.000000E+00 0.000000E+0000E+00 1.151965E-19 0.000000E+00 5.003272E-01 0.000000E+00 0.000000E+00965E-19 0.000000E+00 0.000000E+00 0.000000E+00 5.003272E-01 0.000000E+00 00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 1.000000E+00

b. Axisymmetric Harmonic BeamHarmonic = 157E+02 0.000000E+00 0.000000E+00 0.000000E+00 -1.897354E-19 0.000000E+00 00E+00 1.000157E+02 0.000000E+00 1.355253E-19 0.000000E+00 0.000000E+00 00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 00E+00 1.219727E-19 0.000000E+00 5.003665E-01 0.000000E+00 0.000000E+00 727E-19 0.00000E+00 0.000000E+00 0.000000E+00 5.003665E-01 0.000000E+00 00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

Harmonic = 0

49Linear AnalysisAxisymmetric Harmonic Concentrated Mass Element

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 1.000157E+02 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.00000.0000

Input F(All of

axhcoaxhcoaxhco00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 1.000079E+00

ilesthe following .dat files are in the /tpl/axiharm directory)

File Name Descriptionnmbm.dat 1D beam problemnmh1.dat Axisymmetric harmonic beam problem with harmonic = 1nmh0.dat Axisymmetric harmonic beam problem with harmonic = 0

50 Linear AnalysisEnhancements to the External Superelement Capability

Enhancements to the External Superelement Capability

IntroThe exintroduemploythe featdetails.efficien

Becausenhancsection

SuppV2013externaimpose

The enlogic wNastranand the

With thentries of rotorThis demay beusage ejobs foanalysi

With ththey arematricematricefreedom

The abby theiHowevduplicain the aductionternal superelement (SE) capability involving the use of the EXTSEOUT Case Control command was ced in MSC Nastran in 2004. Since then, this capability has become the most popular and most widely ed SE usage. The reasons for this are many. First, the feature is fully automated and is easy to use. Second, ure allows users to employ SE usage without divulging or sharing proprietary model, material and geometry Finally, when properly used, the capability can result in significant improvements in productivity and cy, particularly when the analysis of large models is involved.

e of the growing popularity of the external SE feature, there have been many requests in recent years for ements related to a variety of features. MSC Nastran 2014 has several new features that are discussed in this .

ort for Multiple Rotors in Multiple External SEs and the Residual.1 does allow for multiple rotors in external SEs. However, it has the restriction that, if we have rotors in an l SE, only one such external SE is allowed to exist and no rotors are then allowed in the residual. This limitation s severe restrictions on the usage of rotors in practical situations and has been removed in MSC Nastran 2014.

hancements in MSC Nastran 2014 required a complete and significant re-design of the current rotordynamics hich treats the definition and usage of rotors together in a consolidated manner. The new design in MSC 2014 separates the definition of rotors from their usage, with the former being handled at the external SE level latter being handled only in the assembly job.

e enhancements in MSC Nastran 2014, any number of ROTORG, ROTORSE and/or ROTORAX Bulk Data that define rotors may be specified in external SEs and the residual, but Bulk Data entries that pertain to usage s (like RGYRO, RSPINR, RSPINT and UNBALNC entries) are allowed and processed only in the residual. sign has the advantage that, once the rotors are defined in the external SEs, different variations of their usage accomplished in the assembly job by having different variations of the RGYRO, RSPINR and/or RSPINT rotor ntries. Thus, this design gives the user the freedom to form different rotordynamic configurations in assembly r performing specific types of analysis like complex eigenvalue analysis or frequency or transient response s.

e above design, gyroscopic matrices and other rotor related matrices are computed for rotors in the SE in which defined (whether it be an external SE or the residual). Speed factors are applied in the residual to rotor related s of all rotors, regardless of whether the rotors are defined in the residual or in upstream SEs. All of these s are then combined appropriately to perform the analysis specified by the user. This design thus gives total to the user to define rotors in any external SE or the residual, but to use them as he desires in the residual.

ove scenario also introduces another interesting aspect into the design. Until now, rotors were identified only r rotor IDs since they were allowed in only one component (either in the residual or in a single external SE). er, with the enhancements in MSC Nastran 2014, it is quite possible that there may very well be rotors with te IDs across external SEs and the residual. In order to allow for this scenario, rotors whose usage is specified ssembly job need to be identified not only by their rotor IDs, but also by the IDs of the SEs in which they are

51Linear AnalysisEnhancements to the External Superelement Capability

defined. To facilitate this, a new field called ROTRSEID has been added to the existing RGYRO, RSPINR and RSPINT Bulk Data entries to specify the ID of the SE in which a particular rotor is defined.

Yet anothat defgeneratinformajobs. Tin exter

SuppThe cu(defineexternaremovefor hanexterna

There aenginesemployuser to withousecondvia app

The fol

The abmodel gassembther point to consider is that the mass summary information for rotors is generated and output only in the jobs ine the rotors. Thus, for instance, if there are rotors in both external SEs and the residual, the assembly job es and outputs rotor mass summary information only for the rotors defined in the residual. The mass summary tion for the rotors defined in upstream external SEs is available only in the corresponding external SE creation

he program points this out via an appropriate user information message in the assembly job if any rotors defined nal SEs are referenced in the assembly job.

ort for Copy and Move/Mirror Capability for External SEsrrent SE capability does support the copy and move/mirror capability for geometrically identical part SEs d after BEGIN SUPER entries), but it does not allow this feature to be employed for geometrically identical l SEs (created using the EXTSEOUT Case Control command). This is a serious limitation that has been d in MSC Nastran 2014 by extending the feature to external SEs. This new capability provides the capability dling and managing external SEs that are geometrically identical by copying and moving/mirroring a primary l SE to generate secondary external SEs.

re many practical cases in which we encounter geometrically identical components. Blades of turbines and and many components in planes and automobiles are examples of such cases. When external SEs are ed to represent such components, the copy and move/mirror feature available in MSC Nastran 2014 allows the employ additional copies of an already reduced external SE (the primary SE) in an assembled configuration t having to perform reduction operations on each of the additional geometrically identical components (the ary SEs). Instead, the boundary matrices for all of the secondary external SEs are obtained automatically

ropriate internal transformations of the corresponding boundary matrices of the primary external SEs.

lowing important points should be noted with regard to the usage of the copy and move/mirror feature:

The primary SE does not include SEs upstream of the primary SE.If the primary SE is a part SE, then the secondary SE is a "G-set" copy of the primary SE. In this case, the boundary, loads, constraints and reduction procedure of a secondary SE can be different from those of its primary SE.If the primary SE is an external SE resulting from the use of the EXTSEOUT Case Control command in an earlier job, then the secondary SE is an "A-set" copy of the primary SE. In this case, the boundary, loads, constraints and reduction procedure of the secondary SE are set and are the same as those of its primary SE.A secondary SE requires the specification of either an SELOC entry or an SEMPLN entry. If an SELOC entry is specified, then an identical copy of its primary SE will be positioned at the location implied by the SELOC entry. If an SEMPLN entry is specified, then a mirror image of the primary SE will be positioned.It should be noted that even a primary external SE can be re-positioned in an assembly run by use of an SELOC or SEMPLN entry.

ove capability greatly enhances user convenience and productivity by eliminating the need to individually eometrically identical external SEs and contributes to enhanced efficiency for performing the analysis of such

led configurations.

52 Linear AnalysisEnhancements to the External Superelement Capability

Ability to Generate Non-Sparse Matrices via the MATOP4 option of the EXTSEOUT Case Control CommandUntil nmatricefile. Cu

The ennegativnegativof n sp

The f06format.

The abmatrice

SamThe morotors ienginescompu

In orde

The genphysica

The moFigureare rotaow, the MATOP4 option of the EXTSEOUT Case Control command allowed for the generation of only sparse s on the OP4 file. MSC Nastran 2014 allows for the option of generating also non-sparse matrices on the OP4 rrently, the MATOP4 option has the following usage:

MATOP4 = n where n is a positive integer that specifies the Fortran unit number of the OP4 file.hancement in MSC Nastran 2014 extends the above usage so that n may be specified as either a positive or a e integer. A positive value will preserve the current usage of generating sparse matrices on the OP4 file. A e value will result in the generation of non-sparse matrices on the OP4 file. In both cases, the absolute value ecifies the Fortran unit number of the OP4 file.

output will clearly indicate to the user whether the matrices on the OP4 file are in sparse format or non-sparse

ove enhancement will facilitate the use of OP4 matrices in non-Nastran environments that require non-sparse s for their usage.

ple Problemdel is a plane with two engines, each consisting of two axisymmetric rotors and engine casings (stators). The n the two engines are identical, but there are small differences in the left and right engine casings. The left and are thus very similar, but not identical. This is demonstrated from the eigenfrequencies for the two engines,

ted from SOL 107 and shown in Table 1, which show that they are very close.

r to compare the results, three different cases are considered as indicated below.

a. Single-shot run: Here, the complete plane with both the engines is analyzed at once, without the usage of external superelements (see Figure 2-2)

b. External SE assembly run using two distinct and separate external SEs: In this case, the left and right engines are part of two separate external superelements with IDs of 200 and 400, respectively. The model used for the creation run of the right engine is shown in Figure 2-3. The model includes both rotating and non-rotating components.

eration of the external SEs employs dynamic reduction. Thus, the A-set DOFs of the external SEs include both l boundary points (as shown in Figure 2) and generalized coordinates (Q-set DOFs).

del for the assembly run with the left and right engines included as external superelements is shown in 2-4. The direction of rotation is specified in the assembly run. For the analysis performed here, both the rotors ting in the same direction.

c. External SE assembly run using one external SE and the MIRROR feature: In this case, only the external SE model for the right engine is used. The left engine is attached to the residual structure by mirroring the right engine about the mirror plane as shown in Figure 2-5. Since the engines are similar but not identical, the results for this case will be close, but not identical, with those from case (b).

53Linear AnalysisEnhancements to the External Superelement Capability

Figure

Figure2-2 Model for single-shot run

2-3 Engine model used for external SE creation run

54 Linear AnalysisEnhancements to the External Supere

msc nastran 2014 release guide

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