文稿案例msc培訓(xùn)model descripion

Section5ModelVerificationModelingPAGEOverview5SingularitiesandMechanisms6MSC.NASTRANAutomaticCheckingProcedure10AUTOSPC11HowAUTOSPCWorks12ProblemswithAutospc14AutospcwithCQUAD4s18AutospcProblems19AutospcOutput21Autospc23AutospcWorkshop24Modeling(cont.)PAGEDiagnosingErrors34ModelDebugging35DebuggingWorkshop39ModelDebugging43DebuggingWorkshop44FurtherModelDebugging49AnalysisHealthChecks53EssentialQAChecks55AppliedLoadSummation64ReactionLoadSummation66ActualAppliedLoadCheck67Modeling(cont.)PAGEEssentialQAChecks–Workshop71GoodModelingPractice72MultiPointConstraints,RigidElements80MultipointConstraints81MultipointConstraintsWorkshop84R-typeElements85RIGIDElements86RIGIDElementsWorkshop97RIGIDElements98RIGIDElementsWorkshop101Modeling(cont.)PAGEUsefulModelSummaryInformation102ELSUM103MAX/MINDISPLACEMENTANDSPCFORCEOUTPUT105ElementGeometryChecks109GEOMCHECK111ElementGeometryChecks113StructuralSymmetry114OverviewTypicalerrors;SingularitiesandMechanismsMSC.NASTRAN’sautomaticcheckingprocedureDiagnosingerrorsHealthcheckstheusershouldbemakingRIGIDelementsandMPC’sElementGeometryChecksSymmetry

Typicalerrors;SingularitiesandMechanismsAsingularityiscausedbyadegreeoffreedomwithoutanystructuralstiffnesspresent,orwithalowstiffnessTheStiffnessMatrixcannotbeinvertedifitisSingularSomeexamplesofsingularitiesare:ForgettingtoeliminateRigidBodyMotionsConnectingDissimilarElementTypesCrossconnectingwrongDegreesofFreedomSingularitiesandMechanismsSingularitiesandMechanisms(cont.)RigidBodyMotionsSufficientNodalDisplacementshouldbespecifiedsothatthe6“rigidbody”modesofmovementarefixed.RigidBodyMotionAdequateConstraintsSingularitiesandMechanisms(cont.)RigidBodyMotionsForgettingto‘Equivalence’inMSC.PATRANorotherpreprocessorsisaverycommonerror.Resultsinunconnectedmeshes.

MSC.NASTRAN’sautomaticcheckingprocedureAUTOSPCIfobvioussingularitiesexist,MSC/NASTRANattemptstoautomaticallydealwiththem.TheBulkDataentryPARAM,AUTOSPC,YESinstructstheprogramtoautomaticallyapplySPCstothesesingularities.PARAM,AUTOSPC,YESisthedefaultinmostofthestructuredsolutions.HowAutospcworksGRID99StiffnessTermsT1T2T3R1R2R3HexaElementGRID99HowAutospcworks(cont.)GRID99StiffnessTermsSuccessfulEliminationofZeroStiffnesstermsT1T2T3R1R2R3HexaElementGRID99ProblemswithAutospcSolidBarT1T2T3R1R2R3T1T2T3R1R2R3HexaElementBarElementGRID99NoEliminationofSolidElementZeroStiffnesstermsProblemswithAutospc(cont.)

HexaElementBarElementGRID99NoEliminationofSolidElementZeroStiffnesstermsT1T2T3R1R2R3CombinedStiffnessTermsProblemswithAutospc(cont.)

HexaElementBarElementGRID993Mechanisms!ProblemswithAutospc(cont.)

HexaElementBarElementGRID99SolutionsManualSPCMPC’s(later)RigidLinks(later)AutospcwithCQUAD4’sGRID106StiffnessCQUAD4T1T2T3R1R2R3T1,R1T3T2,R2R3=0.0GRID106AutospcProblemsGRID106Stiffness2CQUAD4’sPossibleMechanisms!T1T2T3R1R2R3?T3T1T2T3R1R2R3?AutospcProblems(cont.)SolutionsPARAM,K6ROT,kvalueNotmended–forNonLinearusagePARAM,SNORM,anglemendedAllvectorswithin‘a(chǎn)ngle’areaveraged2*angleAutospcOutputOutputincludesagridpointsingularitytable.Thistableshouldbeinspectedcarefullyforpotentialsingularities.Defaultstiffness

ratio=1.0E-8

GRIDPOINTSINGULARITYTABLE

POINTTYPEFAILEDSTIFFNESSOLDUSETNEWUSET

IDDIRECTIONRATIOEXCLUSIVEUNIONEXCLUSIVEUNION

1G60.00E+00BFSBSB

2G60.00E+00BFSBSB

3G60.00E+00BFSBSB

4G60.00E+00BFSBSB

WhatdoestheUSETtermmean?Considerallgridpointandscalarpointdegreesoffreedominafiniteelementmodelasthemembersofasingledisplacementset.Thisglobalsetiscalledtheg-set;thedisplacementsetisknownasug.[Kgg]mustbenonsingularinordertosolvethisequation.Toachieveanonsingularstiffnessmatrix,theusercanspecifytheindependentsubsetsof{ug}tobepartitionedoutduringmatrixreduction.

Forexample:

um Degreesoffreedomeliminatedbymultipointconstraints

us Degreesoffreedomeliminatedbysingle-pointconstraintsEliminationoftheMandSsetsresultsintheF(free)set,whichistypicallysolvedtoobtaintheunknowndisplacements,

Forathoroughdiscussionofconstraintandpartitioneddisplacementsets,seeAppendixBoftheMSC.NastranQuickReferenceGuideandMSC.NASTRANLinearStaticAnalysisUsers’Guide.

AutospcOutput(cont.)AutospcControllingAUTOSPCAll‘failed’DOFarewrittentoGridPointSingularityTableCangetverylarge–obscurerealproblemsWriteout‘failed’DOF’sto.pchFileParam,spcgen,1param,checkout,yes

Re-usegeneratedSPC1dataselectivelyAutospcWorkshopRuntheMSC.NASTRANinputfilessection5_1.bdfsetofsolidelementssection5_2.bdfsetofplateelementsEvaluatetheGridPointSingularityTablesRuntheMSC.NASTRANinputfilesSection5_3.bdfsolid/platecombinationSection5_4.bdfplate/barcombinationEvaluatetheTablesandchecktheFatalMessagesAutospcWorkshop(cont.)section5_1.bdf

AutospcWorkshop(cont.)section5_1.bdf

GRIDPOINTSINGULARITYTABLE0POINTTYPEFAILEDSTIFFNESSOLDUSETNEWUSETIDDIRECTIONRATIOEXCLUSIVEUNIONEXCLUSIVEUNION1G40.00E+00BFFSBS*1G50.00E+00BFFSBS*1G60.00E+00BFFSBS*2G40.00E+00BFFSBS*2G50.00E+00BFFSBS*2G60.00E+00BFFSBS*3G40.00E+00BFFSBS*3G50.00E+00BFFSBS*3G60.00E+00BFFSBS*

GRID1AutospcWorkshop(cont.)section5_2.bdf

AutospcWorkshop(cont.)section5_2.bdf

0GRIDPOINTSINGULARITYTABLE0POINTTYPEFAILEDSTIFFNESSOLDUSETNEWUSETIDDIRECTIONRATIOEXCLUSIVEUNIONEXCLUSIVEUNION2G60.00E+00BFFSBS*3G60.00E+00BFFSBS*4G60.00E+00BFFSBS*5G60.00E+00BFFSBS*6G60.00E+00BFFSBS*7G60.00E+00BFFSBS*8G60.00E+00BFFSBS*9G60.00E+00BFFSBS*10G60.00E+00BFFSBS*

R3=0.0AutospcWorkshop(cont.)section5_3.bdf

HEXA’sCQUAD4’sAutospcWorkshop(cont.)section5_3.bdf

1G60.00E+00BFFSBS*2G60.00E+00BFFSBS*3G60.00E+00BFFSBS*4G60.00E+00BFFSBS*62G40.00E+00BFFSBS*62G50.00E+00BFFSBS*62G60.00E+00BFFSBS*63G40.00E+00BFFSBS*63G50.00E+00BFFSBS*63G60.00E+00BFFSBS*64G40.00E+00BFFSBS*64G50.00E+00BFFSBS*64G60.00E+00BFFSBS*Whathappensalonghere!!GRID13AutospcWorkshop(cont.)section5_3.bdfTHEFOLLOWINGDEGREESOFFREEDOMHAVEFACTORDIAGONALRATIOSGREATERTHAN1.00000E+07ORHAVENEGATIVETERMSONTHEFACTORDIAGONAL.0SUBCASE10GRIDPOINTIDDEGREEOFFREEDOMMATRIX/FACTORDIAGONALRATIOMATRIXDIAGONAL

13R21.71146E+132.13419E+02^^^USERFATALMESSAGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.AutospcWorkshop(cont.)section5_4.bdf

1G60.00E+00BFFSBS*2G60.00E+00BFFSBS*3G60.00E+00BFFSBS*4G60.00E+00BFFSBS*NoGridPointSingularitytermsforGRID13Whathappenshere!!10G60.00E+00BFFSBS*12G60.00E+00BFFSBS*14G60.00E+00BFFSBS*15G60.00E+00BFFSBS*AutospcWorkshop(cont.)section5_4.bdf

THEFOLLOWINGDEGREESOFFREEDOMHAVEFACTORDIAGONALRATIOSGREATERTHAN1.00000E+07ORHAVENEGATIVETERMSONTHEFACTORDIAGONAL.0SUBCASE10GRIDPOINTIDDEGREEOFFREEDOMMATRIX/FACTORDIAGONALRATIOMATRIXDIAGONAL

13R3-7.02842E+154.09108E+05^^^USERFATALMESSAGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.

DiagnosingerrorsModelDebuggingThepreviousworkshopexamplesSection5_3.bdfSection5_4.bdfResultedinFATALerrorsduetothepresenceofmechanisms.Thissectionshowshowtoidentifythetypeoferror.ModelDebugging(cont.)fromfilesection5_3.f06ThisisthemostcommonFATALERRORChecktheFATALMESSAGEIDChecktheDescriptionTHEFOLLOWINGDEGREESOFFREEDOMHAVEFACTORDIAGONALRATIOSGREATERTHAN1.00000E+07ORHAVENEGATIVETERMSONTHEFACTORDIAGONAL.0SUBCASE10GRIDPOINTIDDEGREEOFFREEDOMMATRIX/FACTORDIAGONALRATIOMATRIX

13R21.71146E+132.13419E+02^^^USERFATALMESSAGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.ModelDebugging(cont.)fromfilesection5_3.f06ASingularityorMechanismisindicatedItisseenatGRID13,DOFR2Isanythingspecialaboutthispoint?THEFOLLOWINGDEGREESOFFREEDOMHAVEFACTORDIAGONALRATIOSGREATERTHAN1.00000E+07ORHAVENEGATIVETERMSONTHEFACTORDIAGONAL.0SUBCASE10GRIDPOINTIDDEGREEOFFREEDOMMATRIX/FACTORDIAGONALRATIOMATRIXDIAGONAL

13R21.71146E+132.13419E+02^^^USERFATALMESSAGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.ModelDebugging(cont.)fromfilesection5_4.f06ASingularityorMechanismisindicatedItisseenatGRID13,DOFR3Isanythingspecialaboutthispoint?

THEFOLLOWINGDEGREESOFFREEDOMHAVEFACTORDIAGONALRATIOSGREATERTHAN1.00000E+07ORHAVENEGATIVETERMSONTHEFACTORDIAGONAL.0SUBCASE10GRIDPOINTIDDEGREEOFFREEDOMMATRIX/FACTORDIAGONALRATIOMATRIXDIAGONAL

13R3-7.02842E+154.09108E+05^^^USERFATALMESSAGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.DebuggingWorkshop

UsingSPCorSPC1entries,CorrecttheMSC.NASTRANinputfilesSection5_3.bdf(hint:GRIDS15913formthejoint)Section5_4.bdfEvaluatetheresultsandtheimplicationofthechangesDebuggingWorkshop(cont.)

CorrectionstoSection5_3.bdfEvaluatetheresultsandtheimplicationofthechangesConstrainedDOF4,5,6LooksOK,butbecareful!!DebuggingWorkshop(cont.)

CorrectionstoSection5_3.bdfEvaluatetheresultsandtheimplicationofthechangesThedisplacementofthesolidsectionimpliessmalledgerotationsofconnectingshells–wehaveconstrainedthemoutDebuggingWorkshop(cont.)

CorrectionstoSection5_4.bdfEvaluatetheresultsandtheimplicationofthechangesConstrainedDOF6NocomplicationsseenModelDebuggingSofarwehaveseentwoexamplesofFATALerrorscausedbyexcessivepivotratiosduringananalysisFatalMessage9050InpracticetherearemanychecksthatMSC.NASTRANwillperformtoflagerrorspriortoanalysisinsyntaxcheckingandgeneraldatachecking,aswellasduringtheanalysisTheformoftheFATALmessagewillbesimilar.ThekeyingredientsaretheIDandthedescriptionFurtherdetailsonthemeaningoftheFATALmessagecanbefoundintheReferenceGuide,ormoreconveniently,theOnLineEncyclopediaDebuggingWorkshop

RunSection5_5.bdfEvaluatethemessagesandcorrecttheanalysisDebuggingWorkshop(cont.)Section5_5.f06Whatischaracteristicabouttheelementsinthegroupthataresubjecttowarning?WhatdoestheWARNINGmessageimply?***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=7ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=8ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=9ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=10ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=11ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=12ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=13ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.***USERWARNINGMESSAGE5487(EBCHKD)ORIENTATIONVECTORDEFINEDFORTHEELEMENTID=14ISNEARLYPARALLEL,ITMAYGIVEPOORRESULTS.DebuggingWorkshop(cont.)

Section5_5.f06Again,lookatthegroupcausingtheFATALerrorLookupthemessageIDintheOnLineEncyclopedia***USERFATALMESSAGE2026(EMG)ELEMENT7GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT8GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT9GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT10GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT11GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT12GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT13GEOMETRYYIELDSUNREASONABLEMATRIX.***USERFATALMESSAGE2026(EMG)ELEMENT14GEOMETRYYIELDSUNREASONABLEMATRIX.DebuggingWorkshop(cont.)

OnLineEncyclopedia–resultofsearchfor‘2026’2026***USERFATALMESSAGE2026,ELEMENT****GEOMETRYORMATERIALPROPERTYYIELDSUNREASONABLEMATRIX.Referencedelementgeometryand/orpropertiesyieldanumericalresultwhichcausesanelementstiffnessormassmatrixtobeundefined.Possiblecausesinclude,butarenotlimitedto,(1)thelengthofarodorbariszerobecausetheendpointshavethesamecoordinates,(2)thesidesofatriangleorquadrilateralarecollinearwhichleadstoazerocrossproductindefininganelementcoordinatesystem,(3)thebarorientationvectorisparalleltothebaraxis,or(4)ashearpanelhaszerothicknesssormodulus.CheckGRIDBulkDataentriesdefiningelementendpointsforbaddata.DebuggingWorkshop

Section5_5.bdfCorrectthebardataandrerun$barelementsfollowCBAR11120.1.0.CBAR21230.1.0.CBAR31340.1.0.CBAR41450.1.0.CBAR51560.1.0.CBAR61670.1.0.CBAR71890.1.0.CBAR819100.1.0.CBAR9110120.1.0.CBAR1011210.1.0.CBAR11114150.1.0.CBAR12115160.1.0.CBAR13116180.1.0.CBAR1411870.1.0.CBAR15110210.1.0.CBAR16121220.1.0.CBAR17122230.1.0.CBAR18123240.1.0.CBAR19124250.1.0.CBAR20125160.1.0.FurtherModelDebuggingToenabledeeperunderstandingofthefilesthatcanbeusedfordebuggingtheconceptofDMAPneedstobeintroducedDMAP–Dir