VFRIC界面的帮助文档内容

1.2.4VFRICAbaqusUserSubroutinesReferenceManualUsersubroutinetodefinefrictionalbehaviorforcontactsurfacesOverviewUsersubroutineVFRIC:canbeusedtodefinethefrictionalbehaviorbetweencontactpairsurfaces;能够用来定义接触对表面间的摩擦行为；canbeusedwhentheclassicalCoulombfrictionmodelistoorestrictiveandamorecomplexdefinitionofsheartransmissionbetweencontactingsurfacesisrequired;能够在经典的库伦摩擦模型太具限制性，并且接触表面之间需要一个更为复杂的剪切传输的定义时使用；mustprovidetheentiredefinitionofshearinteractionbetweenthecontactingsurfaces;必须在接触表面之间提供完整的“交互剪切”的定义；canuseandupdatesolution-dependentstatevariables;可以使用并更新基于解的状态变量；cannotbeusedinconjunctionwithsoftenedtangentialsurfacebehavior;and不能够与软化的切向表面行为一起使用；cannotbeusedwiththegeneralcontactalgorithm.不能与通用接触算法一块使用。通用接触算法只可以被用于三维表面；Two-dimensionalsurfacescannotbeusedwiththegeneralcontactalgorithm.二维表面不能与通用接触算法一起使用TerminologyTheuseofusersubroutineVFRICrequiresfamiliaritywiththefollowingterminology.使用VFRIC子程序要求熟悉下列术语。Surfacenodenumbers表面节点编号The“surfacenodenumber”referstothepositionofaparticularnodeinthelistofnodesonthesurface.Forexample,therearenSlvNodnodesontheslavesurface.Numbern,n=1,2...nSlvNod,isthesurfacenodenumberofthenthnodeinthislist;jSlvUid(n)istheuser-definedglobalnumberofthisnode.AnAbaqus/Explicitmodelcanbedefinedintermsofanassemblyofpartinstances(see“Defininganassembly,”Section2.9.1oftheAbaqusAnalysisUser'sManual).InsuchmodelsanodenumberinjSlvUidisaninternallygeneratednodenumber.Iftheoriginalnodenumberandpartinstancenamearerequired,calltheutilityroutineVGETPARTINFO(see“Obtainingpartinformation,”Section2.1.5).“表面节点编号”指的是表面上节点列表里一个特殊点的位置。例如，在从接触面上有nSlvNod个节点。编号n，n=1,2,...nSlvNod，是该节点列表里第n个节点的节点编号；jSlvUid(n)是该节点用户自定义的全局编号。Abaqus/Explicit模型可以按照零件实体的安装来定义（see“Defininganassembly,”Section2.9.1oftheAbaqusAnalysisUser'sManual）。在这样的模型里，jSlvUid里的节点编号是一个内部生成的节点编号。如果要求原始节点编号和零件实体的名字，则调用实用程序VGETPARTINFO。Contactpoints接触点Thenodesontheslavesurfacethatareincontactinthecurrenttimeincrementaredefinedas“contactpoints.”ThenumberofcontactpointsispassedintothissubroutineasnContact.ThearrayjConSlvid(nContact)givesthesurfacenodenumbersforthecontactpoints.从接触面上的那些在当前时间增量接触的节点被定义为“接触点”。接触点的数量作为nContact被传到子程序中。数组jConSlvid(nContact)给出了接触点的表面节点编号。Localcoordinatesystem局部坐标系Alocalcoordinatesystemisdefinedforeachcontactpointtofacilitatespecificationoffrictionalforcesandincrementalslips.Thelocal1-directionforbothtwo-dimensionalandthree-dimensionalcontactistangentialtothemastersurface,anditisdefinedby1sstdd,wheresdistheincrementalslipvector.Theincrementalslipvectorusedtodefine1tcorrespondstotheincrementalslipinthecurrenttimeincrementforpenaltycontactandthepredictedincrementalslipforkinematiccontact.Themastersurfacenormaldirection,n,isthelocal2-directionfortwo-dimensionalcontactandthelocal3-directionforthree-dimensionalcontact.Thelocal2-directionforthree-dimensionalcontactisgivenby21tnt,whichisalsotangenttothemastersurface.ThevectorsareshowninFigure1.2.4–1andFigure1.2.4–2.Thedirectioncosinesfor1tandnwithrespecttotheglobalcoordinatesystemareavailableindirCosT1anddirCosN,respectively.Inthecaseofzeroincrementalslip(0sd)wechooseanarbitrarydirectionfor1tthatisorthogonaltothenormaldirection,n.为每个接触点都定义一个局部坐标系以促进摩擦力和增量滑移的规范。对二维和三维接触来说，局部1-direction是切向于主接触面的，并且被定为1sstdd，其中sd是增量滑移矢量。增量滑移矢量用来定义1t相当于在当前时间增量下对罚接触的增量滑移和对运动学接触的预测到的增量滑移。主接触面的法线方向，n，对二维接触来说是局部2-direction，对三维接触是局部3-direction。21tnt给出了三维接触的局部2-direction的定义，它也相切于主接触面。Figure1.2.4–1和Figure1.2.4–2给出了矢量图。1t的方向余弦和与全局坐标系相关的n分别在dirCosT1和dirCosN里可行。在0增量滑移的情况下（0sd），我们为1t选择一个任意方向，那就是正交于法线方向，n。Figure1.2.4–1Localcoordinatesystemfortwo-dimensionalcontactwithVFRIC.Figure1.2.4–2Localcoordinatesystemforthree-dimensionalcontactwithVFRIC.FrictionalforcesYouspecifythefrictionalforce,fTangential,ateachcontactpointinlocalcoordinatesinthissubroutine.ThearrayfTangentialisdimensionedsuchthatonlythetangentialcomponentscanbespecified.Anycomponentsofthefrictionalforcethatarenotspecifiedwillremainequaltozero.Forthree-dimensionalcontactwithisotropicfriction,onlythefirstcomponentofthefrictionalforceneedbespecifiedsincethesecondcomponentshouldbezero.A“stickforce”ateachcontactpointisprovidedinthearrayfStickForcetotheassistyouinsettingappropriatefrictionalforcevalues.Thestickforceistheforcerequiredtopreventadditional“plastic”slipping.Thestickforceateachcontactpointisprovidedasascalarvalue（标量）asitwouldactinthedirectionoppositeto1t.ThestickforceiscomputedpriortocallingusersubroutineVFRICbyeitherthekinematicorthepenaltycontactalgorithm.See“ContactconstraintenforcementmethodsinAbaqus/Explicit,”Section34.2.3oftheAbaqusAnalysisUser'sManual,fordescriptionsofthekinematicandpenaltycontactalgorithmsandtheuserinterfaceforchoosingbetweenthem.Thefirstcomponentofthefrictionalforceshouldbeintherangebetweenzeroandminusthestickforcevalue.Typically,thestickforcewillbepositiveandthefirstcomponentoftheappliedfrictionalforcewillbenegative,opposingtheincrementalslip.Penaltycontactincludesanelasticslipregimeduetofinitepenaltystiffness,sooccasionally,duringrecoveryofelasticslip,thestickforcewillbenegative,indicatingthatitisappropriateforthefirst