ppt1、接触CONT-LA02-Oldelem1

Thefollowingtopicsarecoveredinthislesson.Lessoncontent:ContactElements,Appendix2:ContactElements,1hour,ContactElements,Surface-Basedvs.ContactElementApproachContactElementsContactElementOutputContactElementVisualization,Surface-Basedvs.ContactElementApproach(1/2),Certaintypesofproblemscurrentlycannotbedoneusingasurface-basedapproach:ContactbetweentwodiscretepointsContactbetweentwopipelinesortubesContactbetweenelementswithporefluidflowingacrossandtangentialtotheinterfaceContactinvolvingaxisymmetricelementswithasymmetricdeformation,Surface-Basedvs.ContactElementApproach(2/2),Intheseproblemscontactelements,ratherthancontactsurfaces,mustbedefined.Mostconceptsdiscussedinthelecturesareequallyvalidwiththecontactelementapproach.Formulation:LagrangemultiplierapproachLocalcontactmodelsFrictionmodels:penaltyandLagrangeapproachLogic:severediscontinuityiterationsMostmodelingtechniquesfromLecture8Conceptsthatdifferare:Inputsyntaxtodescribecontactsurfaces(elements)OutputandpostprocessingTheseconceptswillbediscussedinthislecture.,ContactElements(1/18),ThecontactelementfamiliesinAbaquseachrepresentadifferentgeometric/kinematicframework.GAPelements:small-slidingnode-to-nodecontactISLelements:large-slidingcontactbetweendeformablebodiesIRSelements:large-slidingcontactbetweenarigidandadeformablebodyITTelements:large-slidingcontactbetweentwopipesthatslidewithinornexttoeachother,ContactElements(2/18),GAPelementsGapelementsmonitornode-to-nodecontact.Thebasicvariablesare:ClearancebetweenthenodesDirectionofcontactForcetransmittedbetweenthenodes,ContactElements(3/18),GAPUNIelementsmonitorcontactbetweenanodepairinafixeddirection,n.Thecontactdirectionnneednotbethesameasthedirectionconnectingthenodes,v.Boththecontactdirectionandtheloadtransferpatharefixed.Usethemingeometricallylinearproblemsandwhenrestraintshaveafixeddirection(tubesupport).,ContactElements(4/18),GAPCYLelementsmonitorcontactbetweenanodepairrepresentingarigidcylinderinsidearigidtube(Case1)ortworigidcylinders(Case2):GAPSPHERelementsmonitorcontactbetweenapairofnodesrepresentingeitherarigidsphereinsidearigidsphericalobjectortworigidspheres.,ContactElements(5/18),Syntax:,y,x,*ELEMENT,TYPE=GAPUNI,ELSET=AGAP1001,4,102*GAP,ELSET=AGAP0.1,0.0,1.0,0.0,initialclearance,normaldirection,n(optional),ContactElements(6/18),GAPelementshaveunitareacontactstresscalculatedisactuallythecontactforce.ForelementtypeGAPUNIcontactdependsonlyoninitialclearanceandtherelativedisplacementsofthetwonodesinthedirectionofcontactn.Initialcoordinatesarenotusedatall.Exception:normaldirectioniscalculatedbasedonnodalcoordinatesifitisnotspecified.Dependingonthespecifiedclearance(andtheinitialcoordinatesfortypeGAPCYLandGAPSPH),gapelementsstartinaclosedoropencondition.,ContactElements(7/18),Gapelementscanbeeffectivelyactivatedanddeactivatedwiththe*CONTACTINTERFERENCEoption.,contactconstraint,steps,activate,deactivate,ContactElements(8/18),Gapelementexample:DetroitEdisonpipewhipexperiment(AbaqusExampleProblem2.1.2):Pipemodeledwith10B23elements(8horizontallyand2vertically).Piperestraintmodeledwithasingletrusselementandagapelement.Burstingdiaphragmmodeledasalumpedmass.Thematerialsinthepipeandtherestraintareelastic-plastic.Blowforcemodeledasafollowerpointloadattheendofthestick.,ContactElements(9/18),DetroitEdisonexperiment:,ContactElements(10/18),Gapforcehistory:,ContactElements(11/18),ISLelementsTheseelementsmodelcontactbetweentwodeformingbodiesthatslidealongeachother.Areneededonlywhenmodelingcontactinasymmetric-axisymmetricproblems(CAXAandSAXAelements).Requiresindependentcontactelementsoneachcircumferentialplane.Canbedoneonlyoncertaincircumferentialplanes.ThenodesoftheISLelementformtheslavesurfaceandslidealongtheslidelineattachedtothemastersurface.Useeitherlinear(ISL21A)orquadratic(ISL22A)interpolation.,ContactElements(12/18),Syntax:,*ELEMENT,TYPE=ISL21A,ELSET=SLIDES1001,201,2021002,203,2041003,203,2021004,204,2051005,205,206*INTERFACE,ELSET=SLIDES*SLIDELINE,ELSET=SLIDES,TYPE=LINEAR101,102,103,104,105,ContactElements(13/18),Remarks:Ifonebodyismuchharderthantheotherbody,theISLelementsshouldbeonthesoftbodyandtheslidelineshouldbeonthehardbody.Ifthetwobodiesareequallystiff,theslidelineshouldbeonthebodywiththecoarsemeshandtheISLelementsshouldbeonthebodywiththefinemesh.,ContactElements(14/18),IRSelementsCanbeusedtomodelcontactbetweenarigidsurfaceandadeformablebody.Areneededonlyforseveralspecial-purposeapplications:Whenasubstructurecontactsarigidsurfaceinaxisymmetricmodels.WhenCAXAorSAXAelementtypesareinvolvedincontact.Usethesame“master-slave”conceptsforenforcingcontactconstraintsthatareusedinthesurface-basedcontactcapability.Canbeeitherlinear(IRS21A)orquadratic(IRS22A)elements.Theirmotionisspecifiedviathereferencenode,whichisthelastnodespecifiedintheelementdefinition.The*ASYMMETRIC-AXISYMMETRICoptionspecifies:Theangularpositionofthecircumferentialplaneinwhichthecontactelements(IRSinthiscase)existandThenumberofFouriermodesusedwiththeCAXA(SAXA)elementsthatsharenodeswiththecontactelements.,ContactElements(15/18),Example:Contactinanasymmetric-axisymmetricanalysis*ELEMENT,TYPE=IRS21A,ELSET=elsetname3001,81,82,100004001,1081,1082,10000*INTERFACE,ELSET=elsetname*RIGIDSURFACE,ELSET=elsetname,TYPE=SEGMENTSSTART,.*ASYMMETRIC-AXISYMMETRIC,ANGLE=0.0,MODE=2*ASYMMETRIC-AXISYMMETRIC,ANGLE=180.0,MODE=4The*RIGIDSURFACEoptiondefinespotentialcontactinteractionsbetween:Therigidsurfacebeingdefined(TYPE=SEGMENTSabove)andTheELSETofrigidinterfaceelements.Node10000isthereferencenodeassociatedwiththerigidsurface.Nodes81,82,1082,1082alsobelongtoCAXA(orSAXA)elements.,ContactElements(16/18),ITTelementsITTelementscanbeusedintwo-dimensionalorthree-dimensionalproblems.ITTelementsmodelcontactbetweentwopipesthatslidewithineachother.ContactloadtransferoccursbetweenthenodesoftheITTelement,whichareattachedtotheinnerpipe,andaslideline,whichisattachedtotheouterpipe.ThenodesoftheITTelementsformtheslavesurfaceandslidealongtheslidelineattachedtothemastersurface.Theslidelineidentifiestheouterpipe.,ContactElements(17/18),Syntax:,*ELEMENT,TYPE=ITT21,ELSET=TUBE1001,1011002,1021003,103*INTERFACE,ELSET=TUBEa-b(radialclearance)*SLIDELINE,ELSET=TUBE,TYPE=LINEAR,(SMOOTH=)201,202,203,ContactElements(18/18),Remarks:ITTelementshaveunitarea,sothecontactstresscalculatedisactuallythecontactforce.Fortwo-dimensionalelementITT21contactcanoccuroneithersideofthepipe.Forthree-dimensionalelementITT31contactcanoccuronanysideofthepipe.Thecontactalgorithmisnotsensitivetotheorientationoftheslideline.TheslidelinecanbepartiallyorcompletelymadeintoarigidsurfacebyapplyingboundaryconditionsorMPCstoitsnodes.,ContactElementOutput(1/2),Whentheelementapproachisused,contactoutputisobtainedwiththestandardelementoutputcommands:*ELEMENTOUTPUTforoutputtotheoutputdatabasefile*ELPRINTforprintedoutput*ELFILEforfileoutputThe*CONTACTOUTPUT,*CONTACTPRINT,and*CONTACTFILEoptionscannotbeusedwiththecontactelementapproach.Syntax:*ELPRINT,ELSET=contact_elset_nameoutputvariableidentifiersTheavailableoutputvariablesare:Contactpressure:S11Contactopenings:E11Frictionalstresses:S12,S13Accumulatedrelativetangentialmotions:E12,E13,ContactElementOutput(2/2),Exampleof*ELPRINToutputforcontactelements:ELEMENTOUTPUTTHEFOLLOWINGTABLEISPRINTEDFORELSETISLANDELEMENTTYPEISL21AATTHEINTEGRATIONPOINTSELEMENTPTFOOT-S11S12E11E12NOTE10011CL942.50.0000E+005.7432E-351.0408E-1710012CL588.10.0000E+003.7144E-12-0.505210021CL588.10.0000E+003.7144E-12-0.505210022CL206.40.0000E+005.6593E-15-1.04010031CL206.40.0000E+005.6593E-15-1.04010032OP0.0000E+000.0000E+000.3566-1.29310041OP0.0000E+000.0000E+000.3566-1.29310042OP0.0000E+000.0000E+000.9931-1.40610051OP0.0000E+000.0000E+000.9931-1.40610052OP0.0000E+000.0000E+001.643-1.45610061OP0.0000E+000.0000E+001.643-1.456OP:GAPORINTERFACEOPENCL:GAPORINTERFACECLOSED;NOFRICTIONIntegrationpointsforcontactelementsarealwayslocatedatthenodesoftheelement.,ContactElementVisualization(1/4),Whentheelementapproachisused,youcanvisualizecontactentitiesjustasyoucanwhenusingsurface-basedcontact.Rigidsurfaces(two-dimensional/three-dimensional)Allc