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1、华中科技大学硕士学位论文AbstractToeffectivelyreducecasualtiesincarcrashes,moreandmorehigh-endcarsareequippedwithaco-pilotairbag.Softseamlesslyattachedairbagcardashboardsaremoreandmorewidelyused,becauseofitssafety,beautyandcomfort.Inordertoairbagexpandsuccessfullytoprotectpasseng
2、erandavoiddashboardspiecesflyingouttohurtpassenger,needtooptimizetheweakeningprocessanddevelopreasonableprocessparameters.Toaccuratelystudyonthedamageofsoftseamlesslyattachedairbagcardashboard,requiretoobtainaccuratematerialmodel,whichincludesgettingthebottomofthepla
3、sticmechanism,thedamagemechanism,therheologicalcurve;knowingtheweakeningprocessparametersaffectonthespecimendamageperformance;obtainingweakeningdashboardactualdamagediscipline.Inthispaper,themechanicalparametersandstress-straincurveobtainedbyexperiments.Theexperiment
4、alresultsshowthatthedashboardcommonlyusedmaterialPPitsplasticmechanismiscrazingyield,thedamagemechanismidcrazingplasticdamage,stress-straincurvesshowobviousviscoelasticandviscoplastic.Iusedelasticviscoplasticconstitutivewithviscoplasticdamagetodescribethecomplexconst
5、itutivebehaviorofPPanddevelopedthematerialsubroutine.Analysisstandardspecimentensiletestcalltheabovematerialsubroutines,simulationresultssatisfiedagreewiththeexperimentalresults,thematerialmodelisabletodescribethematerialbehaviorinthispaper.Tostudytheweakeningprocess
6、affectonthespecimendamage,analysisthestressdistributionofspecimenswithaseriesofholesfromthefracturemechanicspointofview,andalsousingfiniteelementanalysisweakenedspecimens.Comparativeanalyticalsolutionoffracturemechanicsandfiniteelementnumericalsolution,finiteelementa
7、nalysiscanreflecttheimpactofweakeningholesonstressdistributionofthespecimen.ThroughexperimentalandsimulationstudythedamageofweakeningspecimenwithdifferentweakeningholesparametersandspecimenwithV-groove.Experimentandsimulationresultsshowthattheweakeningprocesscausethe
8、elongationofspecimenatIII华中科技大学硕士学位论文breakdecreasessharply,theproportionofdamagestrengthdecreaseastheratioofthesectionareadecrease,