Finite element modeling of microstructurally small cracks using single crystal plasticity.pdf

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1、InternationalJournalofFatigue25(2003)877884www.elsevier.com/locate/ijfatigueFiniteelementmodelingofmicrostructurallysmallcracksusingsinglecrystalplasticity∗G.P.Potirniche,S.R.DaniewiczMississippiStateUniversity,DepartmentofMechanicalEngineering,210CarpenterBuilding,P.O.BoxME,MississippiState,MS3976

2、2,USAAbstractFiniteelementsimulationsofsmallfatiguecrackswereperformedusingcrystalplasticitytheorytodescribethedeformationbehaviornearthecracktip.Arate-independentsmallstrainformulationfromcrystalplasticitytheorywasimplemented.Constantamplitudeloadswereapplied,withaloadratioofR=0.3.Crackopeningstre

3、ssesandcracktipopeningdisplacementrangesweresimulatedasthecrackgrewinasinglegrain,aswellaswhenthecrackgrewtowardagrainboundary.Crackgrowthinsinglegrainsindicatedthatstabilizationofthecrackopeningstressesoccursrelativelyrapidly(510mmofcrackgrowth).Studiesofcrackgrowthtowardagrainboundaryrevealedthat

4、,dependingontheorientationoftheadjacentgrain,thecrackgrowthrateissignificantlyaffected.Iftheangleofmisorientationbetweenthetwoadjacentgrainsissmall,theneighboringgraincanincreasethegrowthratenearthegrainboundary.Ifthemisorientationangleishigh,thefatiguecrackgrowthratewillbesignificantlyslowedneartheg

5、rainboundary.Ó2003ElsevierLtd.Allrightsreserved.Keywords:Fatiguecrackpropagation;Smallcrack;Crackclosure;Plasticity;Crystalplasticity1.Introductionthatgeneratedinanisotropicmaterial,resultingindif-ferentplasticity-inducedcrackclosurebehavior.TheinfluenceofmicrostructuralfeaturesonsmallResearchershav

6、eacknowledgedthepotentialofthefatiguecrackgrowthiscomplex.NumeroustheoreticalconstitutiverelationshipsofCPtheoryinexplainingthemodels(Barenblatt[1],ElHaddadetal.[2,3],Chanetparticularbehaviorofcracksinthemicrostructurallyal.[4],Hobson[5],McEvily[6],delosRiosetal.[7smallstage.Riceetal.[10]werethefirs

7、ttoapplyCP9])havebeenproposedforsmallcracksthatincorporatetheorytoafracturemechanicsproblem.TheycomputedtheeffectofmicrostructuralfeaturessuchasgraincracktipplasticzonesformodeIstationaryandgrowingboundarie