ABAQUS粘接单元应用PPT格式课件下载.ppt

ABAQUS粘接单元应用PPT格式课件下载.ppt

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Cohesivesurfaces,T-peelanalysis:

Cohesiveelementsareusedformodelingadhesivepatches,Introduction,Element-basedcohesivebehaviorcohesiveelementsCohesiveelementsallowverydetailedmodelingofadhesiveconnections,includingspecificationofdetailedadhesivematerialproperties,directcontroloftheconnectionmesh,modelingofadhesivesoffinitethickness,etc.CohesiveelementsinAbaqusprimarilyaddresstwoclassesofproblems:

AdhesivejointsAdhesivelayerwithfinitethicknessTypicallythebulkmaterialpropertiesareknownDelaminationAdhesivelayerof“zero”thicknessTypicallythebulkmaterialpropertiesarenotknown,Introduction,Theconstitutivemodelingdependsontheclassofproblem:

Basedonmacroscopicproperties（stiffness,strength）foradhesivejointsContinuumdescription:

anyAbaqusmaterialmodelcanbeusedModelingtechniqueisrelativelystraightforward:

cohesivelayerhasfinitethickness;

standardmaterialmodels（includingdamage）.Thecontinuumdescriptionisnotdiscussedfurtherinthislecture.Basedonatraction-separationdescriptionfordelaminationLinearelasticitywithdamageModelingtechniqueislessstraightforward:

typicalapplicationsusezero-thicknesscohesiveelements;

non-standardconstitutivelawThisapplicationistheprimaryfocusofthislecture,Introduction,Surface-basedcohesivebehaviorcohesivesurfacesThisisasimplifiedandeasywaytomodelcohesiveconnections,usingthetraction-separationinterfacebehavior.Itofferscapabilitiesthatareverysimilartocohesiveelementsmodeledwiththetraction-separationconstitutiveresponse.However,itdoesnotrequireelementdefinitions.Inaddition,cohesivesurfacescanbondanytimecontactisestablished（“sticky”contact）Itisprimarilyintendedforsituationsinwhichinterfacethicknessisnegligiblysmall.Itmustbedefinedasasurfaceinteractionproperty.Damageforcohesivesurfacesisaninteractionproperty,notamaterialproperty.Thekinematicsofcohesivesurfacesisdifferentfromthatofcohesiveelements.Bydefault,theinitialstiffnessoftheinterfaceiscomputedautomatically.,CohesiveElementTechnology,CohesiveElementTechnology,Elementtypes*3DelementsCOH3D8COH3D62DelementCOH2D4AxisymmetricelementCOHAX4Theseelementscanbeembeddedinamodelviasharednodesortieconstraints.,*Cohesiveporepressureelementsarealsoavailable.,CohesiveElementTechnology,Elementandsectiondefinition*ELEMENT,TYPE=COH3D8*COHESIVESECTION,ELSET=.,RESPONSE=TRACTIONSEPARATION,CONTINUUM,GASKET,THICKNESS=SPECIFIED,GEOMETRY,MATERIAL=.Specifythicknessindataline（defaultis1.0）,CohesiveElementTechnology,DefaultthicknessofcohesiveelementsTraction-separationresponse:

UnitthicknessContinuumandgasketresponseGeometricthicknessbasedonnodalcoordinates,CohesiveElementTechnology,OutputvariablesScalardamage（i.e.,degradation）variableSDEGVariablesindicatingwhetherdamageinitiationcriteriametorexceededDiscussedshortlyElementstatusflagSTATUS,CohesiveElementTechnology,ImportofcohesiveelementsThecombinationofAbaqus/StandardandAbaqus/Explicitexpandstherangeofapplicationsforcohesiveelements.Forexample,youcansimulatethedamageinastructureduetoanimpacteventthenstudytheeffectofthedamageonthestructuresloadcarryingcapacity.,ConstitutiveResponseinCohesiveElements,ConstitutiveResponseinCohesiveElements,DelaminationapplicationsTractionseparationlawTypicallycharacterizedbypeakstrength（N）andfractureenergy（GTC）ModedependentLinearelasticitywithdamageAvailableinbothAbaqus/StandardandAbaqus/ExplicitModelingofdamageunderthegeneralframeworkintroducedearlierDamageinitiationTractionorseparation-basedcriterionDamageevolutionRemovalofelements,Typicaltraction-separationresponse,ConstitutiveResponseinCohesiveElements,LinearelasticitywithdamageLinearelasticityDefinesbehaviorbeforetheinitiationofdamageRelatesnominalstresstonominalstrainNominaltractiontoseparationwithdefaultchoiceofunitthicknessUncoupledtractionbehavior:

nominalstressdependsonlyoncorrespondingnominalstrainCoupledtractionbehaviorismoregeneral,*ELASTIC,TYPE=TRACTION,COUPLEDTRACTION,ConstitutiveResponseinCohesiveElements,Theelasticmodulusforthetractionseparationlawshouldbeinterpretedasapenaltystiffness.Forexample,fortheopeningmode:

Kn=Nmax/dninitInAbaqus,nominalstressandstrainquantitiesareusedforthetractionseparationlaw.Ifunitthicknessisspecifiedfortheelement,thenthenominalstraincorrespondstotheseparationvalue.ElasticresponsegovernedbyKn.Ifyouspecifyanon-unitthicknessforthecohesiveelement,youmustscaleyourdatatoobtainthecorrectstiffnessKn.Exampleonnextslide.,ConstitutiveResponseinCohesiveElements,Example:

Peeltestmodel,A,En=Knheff,Geometricthickness（basedonnodalcoordinates）oftheadhesivehgeom=1e-3,B,DamageinitiationMixedmodeconditionsMaximumstress（orstrain）criterion:

Output:

MAXSCRTMAXECRT,ConstitutiveResponseinCohesiveElements,*DAMAGEINITIATION,CRITERION=MAXS,MAXE,ConstitutiveResponseinCohesiveElements,Forexample,forModeI（openingmode）theMAXSconditionimpliesdamageinitiateswhensn=Nmax.,*Damageinitiation,criterion=MAXS290.0E6,200.0E6,200.0E6,Damageinitiationpoint,Nmax,Tmax,Smax,ConstitutiveResponseinCohesiveElements,Quadraticstress（orstrain）interactioncriterion:

NodamageinitiationunderpurecompressionOutput:

QUADSCRTQUADECRT,*DAMAGEINITIATION,CRITERION=QUADS,QUADE,ConstitutiveResponseinCohesiveElements,Summaryofdamageinitiationcriteria,n:

nominalstressinthepurenormalmodes:

nominalstressinthefirstsheardirectiont:

nominalstressinthesecondsheardirection,n:

nominalstraininthepurenormalmodes:

nominalstraininthefirstsheardirectiont:

nominalstraininthesecondsheardirection,wheren,s,andtarecomponentsofrelativedisplacementbetweenthetopandbottomofthecohesiveelement;

andToistheoriginalthicknessofthecohesiveelement.,ConstitutiveResponseinCohesiveElements,DamageevolutionPostdamage-initiationresponsedefinedby:

disthescalardamagevariabled=0:

undamagedd=1:

fullydamageddmonotonicallyincreases,ConstitutiveResponseinCohesiveElements,DamageevolutionisbasedonenergyordisplacementSpecifyeitherthetotalfractureenergyorthepostdamage-initiationeffectivedisplacementatfailureMaydependonmodemixModemixmaybedefinedintermsofenergyortraction,ConstitutiveResponseinCohesiveElements,Displacement-baseddamageevolutionDamageisafunctionofaneffectivedisplacement:

Thepostdamage-initiationsofteningresponsecanbeeitherLinearExponentialTabular,Linearpost-initiationresponse,ConstitutiveResponseinCohesiveElements,Keywordsinterfacefordisplacement-baseddamageevolutionForLINEARandEXPONENTIALsoftening:

Specifytheeffectivedisplacementatcompletefailuredfailrelativetotheeffectivedisplacementatinitiationdinit.ForTABULARsoftening:

Specifythescalardamagevariableddirectlyasafunctionofddinit.Optionallyspecifytheeffectivedisplacementasfunctionofmodemixintabularform.Abaqusassumesthatthedamageevolutionismodeindependentotherwise.,*DAMAGEEVOLUTION,TYPE=DISPLACEMENT,SOFTENING=LINEAR|EXPONENTIAL|TABULAR,MIXEDMODEBEHAVIOR=TABULAR,ConstitutiveResponseinCohesiveElements,Abaqus/CAEinterfacefordisplacement-baseddamageevolution,ConstitutiveResponseinCohesiveElements,Energy-baseddamageevolutionThefractureenergycanbedefinedasafunctionofmodemixusingeitheratabularformoroneoftwoanalyticalforms:

PowerlawBK（Benzeggagh-Kenane）,Forisotropicfailure（GIC=GIIC）,theresponseisinsensitivetothevalueof.,ConstitutiveResponseinCohesiveElements,Keywordsinterfaceforenergy-baseddamageevolutionSpecifyfractureenergyasfunctionofmodemixintabularform,orSpecifythefractureenergyinpurenormalandsheardeformationmodesandchooseeitherthePOWERLAWortheBKmixedmodebehavior,*DAMAGEEVOLUTION,TYPE=ENERGY,SOFTENING=LINEAR|EXPONENTIAL,MIXEDMODEBEHAVIOR=TABULAR|POWERLAW|BK,POWER=value,ConstitutiveResponseinCohesiveElements,Abaqus/CAEinterfaceforenergy-baseddamageevolution,ConstitutiveResponseinCohesiveElements,ExampleTheprecedingdiscussionwasverygeneralinthesensethatthefullrangeofoptionsformodelingtheconstitutiveresponseofcohesiveelementswaspresented.Inthesimplestcase,Abaqusrequiresthatyouinputtheadhesivethicknessheffand10materialparameters:

*Elastic,type=tractionEn,Et,Es*Damageinitiation,criterion=maxsNmax,Tmax,Smax*Damageevolution,type=energy,mixedmodebehavior=bk,power=GIC,GIIC,GIIIC,Whatdoyoudowhenyouonlyhave1propertyandtheadhesivethicknessisessentiallyzero?

Normal（opening）mode:

Diehl,T.,ModelingSurface-BondedStructureswithABAQUSCohesiveElements:

Beam-TypeSolutions,ABAQUSUsersConference,Stockholm,2005.,ConstitutiveResponseinCohesiveElements,Exam