Extended finite element simulation of quasi-brittle fracture in functionally graded materials.pdf

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1、Comput.MethodsAppl.Mech.Engrg.196(2007)4013–4026www.elsevier.com/locate/cmaExtendedfiniteelementsimulationofquasi-brittlefractureinfunctionallygradedmaterialsClaudiaComi,StefanoMariani*DipartimentodiIngegneriaStrutturale,PolitecnicodiMilano,PiazzaL.daVinci32,20133Milano,ItalyReceived5May2006

2、;receivedinrevisedform16February2007;accepted23February2007Availableonline19April2007AbstractThepaperaddressesthesimulationoffractureprocessesinquasi-brittlefunctionallygradedmaterials(FGMs),endowedwithelasticandtoughnesspropertieswhichgraduallyvaryinspace.Toavoidstrongstressgradients,refer

3、enceismadetoFGMswithaweakgra-dation.Anadhocextendedfiniteelementformulation,accountingformaterialgradation,isdevelopedtofollowthepropagationofcohesivecracksinthegradedmedium.Theeffectivenessoftheproposedmethodologyischeckedsimulatingfourpointsbendingtestsonnotchedbeams,madeofaglass-filledepoxy

4、compositematerial,featuringamechanicalgradientparallelandperpendiculartothenotch.Ó2007ElsevierB.V.Allrightsreserved.Keywords:Functionallygradedmaterials;Extendedfiniteelementmethod;Quasi-brittlefracture;Cohesivemodel1.IntroductionnumericalresearcheffortonFGMsisnowadaysdevotedtothissubject.Sev

5、eralresultshavebeenobtainedintheLayeredmaterialsandbi-materialsystemshaveahugelinearelasticfracturecontext;stressintensityfactorsfornumberofengineeringapplicationsrangingfrombiome-non-homogeneouselasticsolidshavebeenanalyticallychanicaldevicestoaircraftengines.Wearresistant,thermalcomputed(

6、seee.g.[2,3])ornumericallyevaluatedbyfiniteresistantandbiologicallycompatiblecoatingsaresignifi-element(FE)analyses(seee.g.[4–6])undervariousloadingcantexamplesofsuchsystems.Thepresenceofdiscreteconditions.Morerecently,cohesivecrackpropagationininterfacesandtherelateddebondingproblemsareoften

7、FGMshasbeenconsideredbothinstaticsandindynamics.theweakpointwhichlimitstheirreliability.In[7,8]FEsimulationswereperformedintroducingcohe-Compositematerialswithspatiallyvariedphasecompo-siveinterfaceelementsalongtheedgesofthebulkelements;sitionorfunctiona