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1、PartI1.Systemwarningmessage7661***SYSTEMWARNINGMESSAGE7661(ROTDR1)THEMASSONROTOR1ATGRID103DOESNOTPASSTHESYMMETRYTESTUSERINFORMATION:RESULTSMAYBEINACCURATESuchasituationmaybeascribetoanerrorofdefineCONM2,pleasecheckit.2.Systemwarningmessage5289***USERFATALMESSAGE5289(WRGMTD)DEP
2、ENDENTDEGREE-OF-FREEDOMGRIDID=101ANDCOMPONENT=2APPEARSONMORETHANONEMPCORRIGIDELEMENTENTRY.SuchasituationmaybeascribetoanerrorofdefineRBE2,changethenodes,tryit.3.DefinitionofUnbalanceThedefinitionofUNBALNC:UNBALNC,100,1.0E-6,102,0.0,1.0,0.04.Userfatalmessage9050^^^USERFATALMESS
3、AGE9050(SEKRRS)^^^RUNTERMINATEDDUETOEXCESSIVEPIVOTRATIOSINMATRIXKLL.^^^USERACTION:CONSTRAINMECHANISMSWITHSPCIORSUPORTIENTRIESORSPECIFYPARAM,BAILOUT,-1TOCONTINUETHERUNWITHMECHANISMS.IfnegativetermsoccuronthefactordiagonalmatrixduringmatrixdecompositionusingtheSPARSE(default)sol
4、ver,UFM9050willcorrectlybeprinted,buttheDOFcontainingnegativefactorsonthefactordiagonalmatrixwillnotbeidentified.TermswhichhavefactordiagonalratiosgreaterthanthevalueofPARAM,MAXRATIOwillbeproperlyidentified.Avoidance:IftheproblemisrunusingNASTRANSPARSE=1,thedegreesoffreedomwit
5、hnegativetermsinthefactordiagonalmatrixwillbeproperlyidentifiedinthelisting.Thereasonmaybe:(1)arigidtranslation,somedofswerenotconstrainted(2)arigidconnectionbetweenthetwoelements.(3)therearesomeduplicatednodesinthemodel.TheEquivalenceactionshouldbeexecuted.5.GridPointSingular
6、ityTable导致奇异性的原因，通常是表达结构的单元没有将相邻单元的对应节点的自由度连接起来。识别奇异性自由度的原则，也针对于这个方面，用户应仔细检查分析集的奇异自由度，并清除它们。MSC.NastranautomaticallyidentifiesandconstrainssingularitiesinthestiffnessmatrixusingaparametercalledAUTOSPC.AGridPointSingularityTableisprintedintheoutput(.f06)fileshowingwhichDOFswere
7、constrained.Ifthistableispresentintheoutput,itiscriticalthatyouinspecttheresultscarefullyandunderstandwhichDOFsweresingularandwhy-itispossiblethatsingularDOFsareduetomodelingerrors.PayattentiontotheDOFSthatwereconstrainedbythesoftwareautomatically.Understandthemeaning.Degreeso
8、ffreedomthatareeitherunconnectedorveryweaklycoupledtothefinit
