VFRIC界面的帮助文档内容

1.2.4 VFRIC 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;能够用来定义接触对表面间的摩擦行为；can be used when the classical Coulomb friction model is too restrictive and a more complex definition of shear transmission between contacting surfaces is required;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；must provide the entire definition of shear interaction between the contacting surfaces;必须在接触表面之间提供完整的“交互剪切”的定义；can use and update solution-dependent state variables;可以使用并更新基于解的状态变量；cannot be used in conjunction with softened tangential surface behavior; and不能够与软化的切向表面行为一起使用；cannot be used with the general contact algorithm.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-dimensional surfaces cannot be used with the general contact algorithm.二维表面不能与通用接触算法一起使用TerminologyThe use of user subroutine VFRIC requires familiarity with the following terminology.使用VFRIC子程序要求熟悉下列术语。

Surface node numbers 表面节点编号The “surface node number” refers to the position of a particular node in the list of no des on the surface. For example, there are nSlvNod nodes on the slave surface. Number n, n=1, 2 ... nSlvNod, is the surface node number of the n th node in this list; jSlvUid(n) is the user-defined global number of this node. An Abaqus/Explicit model can be definedin terms of an assembly of part instances (see “Defining an assembly,” Section 2.9.1 of the Abaqus Analysis User's 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“Defining an assembly,” Section 2.9.1 of the Abaqus Analysis User's Manual）。

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。

Contact points 接触点The nodes on the slave surface 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.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。

Local coordinate system 局部坐标系A 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 surface, and it is defined by 1s s t d d =, where s d is the incremental slip vector. The incremental slip vectorused to define 1t corresponds to the incremental slip in the current time increment for penalty contact and the predictedincremental slip for kinematic contact. The master surface normal direction, n, is the 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 21t n t =⨯, which is also tangent to the master surface. The vectors are shown inFigure 1.2.4–1 and Figure 1.2.4–2. The direction cosines for 1t and n with respect to the global coordinate system are available in dirCosT1 and dirCosN, respectively. In the case of zero incremental slip (0s d =) we choose an arbitrarydirection for 1t that is orthogonal to the normal direction, 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1s s t d d =，其中s d 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 。

21t n t =⨯给出了三维接触的局部2-direction的定义，它也相切于主接触面。

Figure 1.2.4–1和 Figure 1.2.4–2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（0s d =），我们为1t 选择一个任意方向，那就是正交于法线方向，n 。

Figure 1.2.4–1 Local coordinate system for two-dimensional contact with VFRIC .Figure 1.2.4–2 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 tangential 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 f irst component of the frictional force need be specified since the second component should be zero. A “stick force” 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（标量）as it would act in the direction opposite tot. The stick force is computed1prior 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 User's Manual, for descriptions of the kinematic 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 will 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 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.在子程序的局部坐标系中的每一个接触点上，你要指定摩擦力，fTangential。