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1、ShearLockingandHourglassinginMSCNastran,ABAQUS,andANSYSEricQiuliSunAbstractAsolidbeamandacompositebeamwereusedtocomparehowMSCNastran,ABAQUS,andANSYShandledthenumericaldifficultiesofshearlockingandhourglassing.Theirtipdisplacementsandfirstmodeswerecomputed,normal
2、ized,andlistedinmultipletablesundervarioussituations.Itwasfoundthatfullyintegratedfirstordersolidelementsinthesethreefiniteelementcodesexhibitedsimilarshearlocking.Itisthusrecommendedthatoneshouldavoidusingthistypeofelementinbendingapplicationsandmodalanalysis.T
3、herewas,however,nosuchshearlockingwithfullyintegratedsecondordersolidelements.ReducedintegrationfirstordersolidelementsinABAQUSandANSYSsufferedfromhourglassingwhenameshwascoarse.Iftherewasonlyonelayerofelements,thereportedfirstmodeofthebeamexamplesfromABAQUSandA
4、NSYSwasexcessivelysmallerthantheconvergedsolutionsduetohourglassing.Atleastfourlayersofelementsshould,therefore,beusedinABAQUSandANSYS.MSCNastranoutperformedABAQUSandANSYSbyvirtuallyeliminatingtheannoyinghourglassingofreducedintegrationfirstorder3Dsolidelementsb
5、ecauseitemployedbubblefunctionstocontrolthepropagationofnon-physicalzero-energymodes.Eveniftherewasonlyonelayerofsuchelements,MSCNastrancouldstillmanagetoproducereasonablyaccurateresults.Thisisveryconvenientbecauseitismuchlesspronetoerrorswhenusingreducedintegra
6、tionfirstorder3DsolidelementsinMSCNastran.IntroductionInfiniteelementanalysis(FEA),shearlockingandhourglassingaretwomajornumericalproblemsbecausetheymaycausespurioussolutionsincertainsituations.Theyare,however,usuallynotdiscussedintheconventionalcollegefiniteele
7、menttextbooks(Logan,1992).Itis,therefore,necessarytohaveasolidunderstandingofhowmajorcommercialFEAcodeshandlethesenumericaldifficultiesbeforeperforminganyseriousengineeringanalysis.Startwithacantileverbeamexample(Fig.1).AF=40NBH=6mmFig.1BeamExample1Thedimensions
8、ofthebeamareLWH××=150mmmmmm×4×6.ThebeamisfixedattheendAandaforceof40NisappliedatthefreeendB.Thematerialproperties(MatthewsandDavies,2003)are32EG==146.9Pa146.910×Nmm11
