1、1.2.4VFRIC Abaqus User Subroutines Reference ManualUser subroutine to define frictional behavior for contact surfacesOverviewUser subroutine VFRIC: can be used to define the frictional behavior between contact pair surfaces;能夠用來(lái)定義接觸對(duì)表面間的摩擦行為； can be used when the classical Coulomb friction model is

2、too restrictive and a more complex definition of shear transmission between contacting surfaces is required;能夠在經(jīng)典的庫(kù)倫摩擦模型太具限制性，并且接觸表面之間需要一個(gè)更為復(fù)雜的剪切傳輸?shù)亩x時(shí)使用； must provide the entire definition of shear interaction between the contacting surfaces;必須在接觸表面之間提供完整的“交互剪切”的定義； can use and update solution-depe

3、ndent state variables;可以使用并更新基于解的狀態(tài)變量； cannot be used in conjunction with softened tangential surface behavior; and不能夠與軟化的切向表面行為一起使用； cannot be used with the general contact algorithm.不能與通用接觸算法一塊使用。通用接觸算法只可以被用于三維表面；Two-dimensional surfaces cannot be used with the general contact algorithm.二維表面不能與通用接

4、觸算法一起使用TerminologyThe use of user subroutine VFRIC requires familiarity with the following terminology.使用VFRIC子程序要求熟悉下列術(shù)語(yǔ)。Surface node numbers 表面節(jié)點(diǎn)編號(hào)The “surface node number” refers to the position of a particular node in the list of nodes on the surface. For example, there are nSlvNod nodes on the

5、slave surface. Number n, n=1, 2 . nSlvNod, is the surface node number of the nth node in this list; jSlvUid(n) is the user-defined global number of this node. An Abaqus/Explicit model can be defined in terms of an assembly of part instances (see “Defining an assembly,” Section 2.9.1 of the Abaqus An

6、alysis Users Manual). In such models a node number in jSlvUid is an internally generated node number. If the original node number and part instance name are required, call the utility routine VGETPARTINFO (see “Obtaining part information,” Section 2.1.5). “表面節(jié)點(diǎn)編號(hào)”指的是表面上節(jié)點(diǎn)列表里一個(gè)特殊點(diǎn)的位置。例如，在從接觸面上有nSlvNo

7、d個(gè)節(jié)點(diǎn)。編號(hào)n，n=1,2, . nSlvNod，是該節(jié)點(diǎn)列表里第n個(gè)節(jié)點(diǎn)的節(jié)點(diǎn)編號(hào)；jSlvUid(n)是該節(jié)點(diǎn)用戶自定義的全局編號(hào)。Abaqus/Explicit模型可以按照零件實(shí)體的安裝來(lái)定義（see “Defining an assembly,” Section 2.9.1 of the Abaqus Analysis Users Manual）。在這樣的模型里，jSlvUid里的節(jié)點(diǎn)編號(hào)是一個(gè)內(nèi)部生成的節(jié)點(diǎn)編號(hào)。如果要求原始節(jié)點(diǎn)編號(hào)和零件實(shí)體的名字，則調(diào)用實(shí)用程序VGETPARTINFO。Contact points 接觸點(diǎn)The nodes on the slave surfac

8、e that are in contact in the current time increment are defined as “contact points.” The number of contact points is passed into this subroutine as nContact. The array jConSlvid(nContact) gives the surface node numbers for the contact points. 從接觸面上的那些在當(dāng)前時(shí)間增量接觸的節(jié)點(diǎn)被定義為“接觸點(diǎn)”。接觸點(diǎn)的數(shù)量作為nContact被傳到子程序中。數(shù)組j

9、ConSlvid(nContact) 給出了接觸點(diǎn)的表面節(jié)點(diǎn)編號(hào)。Local coordinate system 局部坐標(biāo)系A(chǔ) local coordinate system is defined for each contact point to facilitate specification of frictional forces and incremental slips. The local 1-direction for both two-dimensional and three-dimensional contact is tangential to the master s

10、urface, and it is defined by, where is the incremental slip vector. The incremental slip vector used to define corresponds to the incremental slip in the current time increment for penalty contact and the predicted incremental slip for kinematic contact. The master surface normal direction, n, is th

11、e local 2-direction for two-dimensional contact and the local 3-direction for three-dimensional contact. The local 2-direction for three-dimensional contact is given by, which is also tangent to the master surface. The vectors are shown in Figure 1.2.41 and Figure 1.2.42. The direction cosines for a

12、nd n with respect to the global coordinate system are available in dirCosT1 and dirCosN, respectively. In the case of zero incremental slip () we choose an arbitrary direction for that is orthogonal to the normal direction, n. 為每個(gè)接觸點(diǎn)都定義一個(gè)局部坐標(biāo)系以促進(jìn)摩擦力和增量滑移的規(guī)范。對(duì)二維和三維接觸來(lái)說(shuō)，局部1-direction是切向于主接觸面的，并且被定為，其中

13、是增量滑移矢量。增量滑移矢量用來(lái)定義相當(dāng)于在當(dāng)前時(shí)間增量下對(duì)罰接觸的增量滑移和對(duì)運(yùn)動(dòng)學(xué)接觸的預(yù)測(cè)到的增量滑移。主接觸面的法線方向，n，對(duì)二維接觸來(lái)說(shuō)是局部2-direction，對(duì)三維接觸是局部3-direction。給出了三維接觸的局部2-direction的定義，它也相切于主接觸面。Figure 1.2.41和 Figure 1.2.42給出了矢量圖。的方向余弦和與全局坐標(biāo)系相關(guān)的n分別在dirCosT1和dirCosN里可行。在0增量滑移的情況下（），我們?yōu)檫x擇一個(gè)任意方向，那就是正交于法線方向，n。Figure 1.2.41 Local coordinate system for tw

14、o-dimensional contact with VFRIC.Figure 1.2.42 Local coordinate system for three-dimensional contact with VFRIC.Frictional forcesYou specify the frictional force, fTangential, at each contact point in local coordinates in this subroutine. The array fTangential is dimensioned such that only the tange

15、ntial components can be specified. Any components of the frictional force that are not specified will remain equal to zero. For three-dimensional contact with isotropic friction, only the first component of the frictional force need be specified since the second component should be zero. A “stick fo

16、rce” at each contact point is provided in the array fStickForce to the assist you in setting appropriate frictional force values. The stick force is the force required to prevent additional “plastic” slipping. The stick force at each contact point is provided as a scalar value（標(biāo)量） as it would act in

17、 the direction opposite to . The stick force is computed prior to calling user subroutine VFRIC by either the kinematic or the penalty contact algorithm. See “Contact constraint enforcement methods in Abaqus/Explicit,” Section 34.2.3 of the Abaqus Analysis Users Manual, for descriptions of the kinem

18、atic and penalty contact algorithms and the user interface for choosing between them. The first component of the frictional force should be in the range between zero and minus the stick force value. Typically, the stick force will be positive and the first component of the applied frictional force w

19、ill be negative, opposing the incremental slip. Penalty contact includes an elastic slip regime due to finite penalty stiffness, so occasionally, during recovery of elastic slip, the stick force will be negative, indicating that it is appropriate for the first component of the frictional force to be

20、 positive (i.e., acting in the same direction as the incremental slip). A noisy or unstable solution is likely to result if the first component of fTangential is set outside of the range between zero and negative the value of the stick force.在子程序的局部坐標(biāo)系中的每一個(gè)接觸點(diǎn)上，你要指定摩擦力，fTangential。ftangential數(shù)組被標(biāo)出，這

21、樣只有切線分量能夠被標(biāo)明。任何沒(méi)有標(biāo)明的摩擦力分量將仍為0。對(duì)三維各向同性的摩擦接觸，只有摩擦力的第一個(gè)分量需要被表明出來(lái)，既然第二個(gè)分量為0。在數(shù)組fStickForce每個(gè)接觸點(diǎn)上提供了一個(gè)“粘附力”來(lái)幫助你設(shè)定恰當(dāng)?shù)哪Σ亮χ?。該粘附力是避免額外的“塑性”滑移所需要的力。每一個(gè)接觸點(diǎn)上的粘附力都是標(biāo)量，它能夠沿著與相反的方向。該粘附力在調(diào)用用戶子程序之前就被或者動(dòng)態(tài)接觸算法或者罰接觸算法計(jì)算出來(lái)。See “Contact constraint enforcement methods in Abaqus/Explicit,” Section 34.2.3 of the Abaqus Anal

22、ysis Users Manual，After user subroutine VFRIC is called, frictional forces that oppose the forces specified at the contact points are distributed to the master nodes. For balanced master-slave contact we then compute weighted averages of the frictional forces for both master-slave orientations. Thes

23、e forces are directly applied if the penalty contact algorithm is being used. If the kinematic contact algorithm is being used, the frictional forces are converted to acceleration corrections by dividing by the nodal masses.User subroutine interface(用戶子程序界面)subroutine vfric(C Write only - 1 fTangent

24、ial, C Read/Write - 2 statev,C Read only - 3 kStep, kInc, nContact, nFacNod, nSlvNod, nMstNod, 4 nFricDir, nDir, nStateVar, nProps, nTemp, nPred, numDefTfv, 5 jSlvUid,jMstUid, jConSlvid, jConMstid, timStep, timGlb, 6 dTimCur, surfInt, surfSlv, surfMst, lContType, 7 dSlipFric, fStickForce, fTangPrev,

25、 fNormal, frictionWork, 8 shape, coordSlv, coordMst, dirCosSl, dircosN, props, 9 areaSlv, tempSlv, preDefSlv, tempMst, preDefMst) C include vaba_param.incC character*80 surfInt, surfSlv, surfMstC dimension props(nProps), statev(nStateVar,nSlvNod), 1 dSlipFric(nDir,nContact), 2 fTangential(nFricDir,n

26、Contact), 3 fTangPrev(nDir,nContact), 4 fStickForce(nContact), areaSlv(nSlvNod), 5 fNormal(nContact), shape(nFacNod,nContact), 6 coordSlv(nDir,nSlvNod), coordMst(nDir,nMstNod), 7 dirCosSl(nDir,nContact), dircosN(nDir,nContact), 8 jSlvUid(nSlvNod), jMstUid(nMstNod), 9 jConSlvid(nContact), jConMstid(n

27、FacNod,nContact) 1 tempSlv(nContact), preDefSlv(nContact,nPred), 2 tempMst(numDefTfv), preDefMst(numDefTfv,nPred) user coding to define fTangential and, optionally, statev return endVariable to be definedfTangential(nFricDir, nContact)為摩擦力分量矩陣，不存在摩擦力時(shí)，它為零矩陣，一直到人為地更新重設(shè)為止；This array must be updated to

28、 the current values of the frictional force components for all contact points in the local tangent directions. See Figure 1.2.41 and Figure 1.2.42 for definition of the local coordinate system. This array will be zero (no friction force) until you reset it.Variable that can be updatedstatev(nstateVa

29、r, nSlvNod)：該矩陣包含了從接觸面所有節(jié)點(diǎn)上用戶定義的solution-dependent狀態(tài)變量；This array contains the user-defined solution-dependent state variables for all the nodes on the slave surface. You define the size of this array (see “Frictional behavior,” Section 33.1.5 of the Abaqus Analysis Users Manual, for more informatio

30、n). This array will be passed in containing the values of these variables prior to the call to user subroutine VFRIC. If any of the solution-dependent state variables is being used in conjunction with the friction behavior, it must be updated in this subroutine. The state variables are available eve

31、n for slave nodes that are not in contact. This may be useful when, for example, the state variables need to be reset for slave nodes that are not in contact.Variables passed in for informationkStep: 為載荷步； Step number.kInc ：為增量步； Increment number.nContact：為發(fā)生接觸的從接觸面節(jié)點(diǎn)數(shù)； Number of contacting slave no

32、des.nFacNod：值等于2時(shí)主接觸面為二維，等于3時(shí)為三維接觸，如果把主接觸面作為剛性面，則其值為零； Number of nodes on each master surface facet (nFacNod is 2 for two-dimensional surfaces, nFacNod is 4 for three-dimensional surfaces). If the master surface is an analytical rigid surface, this variable is passed in as 0.nSlvNod：為從接觸面節(jié)點(diǎn)數(shù) Number

33、of slave nodes.nMstNod：為主接觸面節(jié)點(diǎn)數(shù)； Number of master surface nodes, if the master surface is made up of facets. If the master surface is an analytical rigid surface, this variable is passed in as 0.nFricDir：為接觸點(diǎn)處的切向數(shù)； Number of tangent directions at the contact points (nFricDir = nDir - 1).nDir：為接觸點(diǎn)的參考

34、坐標(biāo)維數(shù)； Number of coordinate directions at the contact points. (In a three-dimensional model nDir will be two if the surfaces in the contact pair are two-dimensional analytical rigid surfaces or are formed by two-dimensional elements.)nStateVar：用戶定義的狀態(tài)變量的數(shù)目; Number of user-defined state variables.nPro

35、ps：摩擦模型需要調(diào)用的用戶定義屬性值數(shù)目； User-specified number of property values associated with this friction model.nTemp：等于1考慮溫度影響，等于0不考慮溫度的影響； 1 if the temperature is defined and 0 if the temperature is not defined.nPred：為預(yù)定義的場(chǎng)變量數(shù)； Number of predefined field variables.numDefTfv： Equal to nContact if the master su

36、rface is made up of facets. If the master surface is an analytical rigid surface, this variable is passed in as 1.jSlvUid(nSlvNod)：為用戶定義的從接觸面節(jié)點(diǎn)全局坐標(biāo)矩陣；This array lists the user-defined global node numbers (or internal node numbers for models defined in terms of an assembly of part instances) of the n

37、odes on the slave surface.jMstUid(nMstNod)：為用戶定義的主接觸面節(jié)點(diǎn)全局坐標(biāo)矩陣； This array lists the user-defined global node numbers (or internal node numbers for models defined in terms of an assembly of part instances) of the nodes on the master surface. If the master surface is an analytical rigid surface, this

38、array is passed in as a dummy array.jConSlvid(nContact)：為從接觸面發(fā)生接觸的節(jié)點(diǎn)號(hào)矩陣； This array lists the surface node numbers of the slave surface nodes that are in contact.jConMstid(nFacNod, nContact)：為主接觸面發(fā)生接觸的節(jié)點(diǎn)號(hào)矩； This array lists the surface node numbers of the master surface nodes that make up the facet

39、with which each contact point is in contact. If the master surface is an analytical rigid surface, this array is passed in as a dummy array.timStep：為時(shí)間步的大?。?Value of step time.timGlb：為所需的總時(shí)間； Value of total time.dtimCur：為當(dāng)前時(shí)間增量； Current increment in time from to .surfInt：為用戶指定的相互作用表面的名稱，向左對(duì)齊； User-s

40、pecified surface interaction name, left justified.surfSlv：為從接觸面的名稱； Slave surface name.surfMst：為主接觸面的名稱； Master surface name.lContType：為接觸類型標(biāo)志符； Contact type flag. This flag is set based on the type of constraint enforcement method (see “Contact constraint enforcement methods in Abaqus/Explicit,” Se

41、ction 34.2.3 of the Abaqus Analysis Users Manual) being used: 1 for kinematic contact and 2 for penalty contact. Stick conditions are satisfied exactly with the kinematic contact algorithm; they are satisfied only approximately (subject to an automatically chosen penalty stiffness value) with the pe

42、nalty contact algorithm.dSlipFric(nDir, nContact)：為當(dāng)前時(shí)間增量步下的局部坐標(biāo)系中每個(gè)接觸點(diǎn)的增量摩擦滑動(dòng)力； This array contains the incremental frictional slip during the current time increment for each contact point in the current local coordinate system. These incremental slips correspond to tangential motion in the time in

43、crement from to . For penalty contact this incremental slip is used to define the local coordinate system at each contact point (see Figure 1.2.41 and Figure 1.2.42) so that only the first component of dSlipFric can be nonzero in the local system. The contact points for kinematic contact are determi

44、ned based on penetrations detected in the predicted configuration (at ), and the predicted incremental slip direction is used to define the local coordinate system at each contact point. If the slip direction changes between increments, dSlipFric may have a nonzero component in the local 2-direction

45、 and, if the surface is faceted and the contact point moves from one facet to another, in the local 3-direction.fStickForce(nContact)：為在每個(gè)接觸點(diǎn)上執(zhí)行粘著接觸時(shí)索要求的摩擦力的大小矩陣； This array contains the magnitude of frictional force required to enforce stick conditions at each contact point. For kinematic contact t

46、his force corresponds to no slip; for penalty contact this force depends on the previous frictional force, the value of the penalty stiffness, and the previous incremental slip. The penalty stiffness is assigned automatically. Occasionally, during recovery of elastic slip associated with the penalty

47、 method, the stick force will be assigned a negative value.fTangPrev(nDir, nContact)：為之前載荷步計(jì)算出的摩擦力組件值矩陣； This array contains the values of the frictional force components calculated in the previous increment but provided in the current local coordinate system (zero for nodes that were not in contact

48、).fNormal(nContact)：當(dāng)前時(shí)間步的最后接觸點(diǎn)上的正應(yīng)力的大小矩陣； This array contains the magnitude of the normal force for the contact points applied at the end of current time increment; i.e., at time .frictionWork：為分析過(guò)程中整個(gè)模型的所有摩擦損耗大?。?This variable contains the value of the total frictional dissipation in the entire model from the beginning of the analysis. The units are energy per unit area.shape(nFacNod, nContact)：為主接觸面上點(diǎn)的形狀函數(shù)矩陣； For each contact point this array contains the shape functions of the nodes o