22.1.4 - Frictional - behavior - - 摩擦行为(6)

接触，精确的分解粘着/滑移行为而带来的拉格朗日乘子方程增加的成本得不偿失。

Input File Usage: *FRICTION, LAGRANGE

ABAQUS/CAE Usage: Interaction module: contact property editor:

MechanicalTangential Behavior: Friction formulation: Lagrange Multiplier

Kinematic method for imposing frictional constraints in ABAQUS/Explicit 在ABAQUS/Explicit里强加摩擦约束的运动学方法

By default, the contact pair algorithm in ABAQUS/Explicit uses a kinematic method for imposing frictional constraints (see “Contact formulation for ABAQUS/Explicit contact pairs,” Section 21.4.4). The kinematic method applies sticking constraints in a way similar to the optional Lagrange multiplier method in ABAQUS/Standard; however, the algorithm is quite different. The value of the force required to enforce sticking at a node is first calculated using the mass associated with the node; the distance the node has slipped; the time increment; and additionally for softened contact, the current value of the elastic slip and the elastic slip versus shear stress slope. For hard contact this sticking force is that which is required to maintain the node's position on the opposite surface in the predicted configuration. For softened contact this force is consistent with the user-specified value for the slope of the shear stress versus elastic slip relationship. The sticking force for each node is calculated using the mass associated with the node, the distance the node has slipped, the shear traction-elastic slip slope (if softened contact is specified in the tangential direction), and the time increment. If the shear stress at the node calculated using this force is less than , the node is considered to be sticking and this force is applied to each surface in opposing directions. If the shear stress exceeds , the surfaces are slipping and the force corresponding to is applied. In either case the forces result in acceleration corrections tangential to the surface at the slave node and either the nodes of the master surface facet or the points on the analytical rigid surface that it contacts. ABAQUS/Explicit中的接触对算法默认使用运动学方法来强加摩擦约束（见“Contact formulation for ABAQUS/Explicit contact pairs,” Section 21.4.4）。运动学方法应用粘着约束的方法类似于ABAQUS/Standard中可选的拉格朗日乘子法；然而，算法却大不同。加强节点粘着约束所需力的值首先用节点质量、节点滑移距离、时间增量和附加的对软接触而言的当前弹性滑移值和弹性滑移对剪应力曲线斜率来计算。对于硬接触这种粘着力用来保持预测外形的对面

节点位置。对于软接触，这种力与用户定义的剪应力对弹性滑移关系曲线斜率值一致。每个节点的粘着力是用节点质量、节点滑移距离、剪应力-弹性滑移斜率（如果再切向定义了软接触）和时间增量来计算。如果用该力计算的节点剪应力小于，节点为粘着，且该力应用于每个相对方向的面上。如果剪应力超过

，表面为滑动状态，且应用相当于的力。任一情况该力都导致修正从面节点、主面接触节点或解析刚面接触点切向加速。

Defining a friction model in user subroutine FRIC or VFRIC

在用户子程序FRIC或VFRIC中定义摩擦模型

For more complex definitions of the shear stress transmission between contacting surfaces (including cases where solution-dependent state variables are needed in the formulation), ABAQUS/Standard provides user subroutine FRIC (“FRIC,” Section 25.2.8) and ABAQUS/Explicit provides user subroutine VFRIC (“VFRIC,” Section 25.3.2). You define the shear interaction between the contact surfaces in the subroutine.

对于更复杂的剪应力在接触面间传递（包括方程需要依赖解的状态变量的情况）的定义，ABAQUS/Standard提供用户子程序FRIC（“FRIC,” Section 25.2.8），ABAQUS/Explicit提供用户子程序VFRIC（“VFRIC,” Section 25.3.2）。你可以在子程序里定义两接触面间剪切相互作用。

You can indicate the number of solution-dependent state variables that will be defined in FRIC or VFRIC, n.

你可以指出在FRIC或VFRIC里定义的依赖于结果的状态变量的个数n。 You can enter data needed by the user subroutine directly in the friction definition. This method can be useful if the coefficients of friction used by the subroutine differ for various contact pairs in a model or are to be changed from analysis to analysis. They can be given as analysis data rather than incorporated directly into the subroutine, which means that the subroutine is simpler and does not have to be modified each time different coefficients are used.

你可以直接在摩擦定义里输入用户子程序需要的数据。如果模型里子程序用的摩擦系数在不同的接触对里不同或者在各个分析不同，那么此法非常有用。它们可作为分析数据给出而不是直接合并到子程序，这意味着子程序更简单且不用每当用不同摩擦系数时都修改子程序。

User subroutine VFRIC cannot be used in conjunction with softened tangential behavior or with the general contact algorithm.

Solution-dependent state variables defined in VFRIC cannot be output to the output database file (.odb) or to the results file (.fil). 用户子程序VFRIC不能与软切向行为和通用接触算法共用。VFRIC里定义的依赖解的状态变量不能输出到输出数据库文件（.odb）或结果文件（.fil）。 User subroutines FRIC and VFRIC allow for a more complex definition of frictional behavior. See “User-defined interfacial constitutive

behavior,” Section 22.1.5, for information on a more general interface for defining the complete mechanical interaction between surfaces, including the interaction in the normal direction as well as the frictional behavior in the tangential direction.

用户子程序FRIC和VFRIC允许定义更复杂的摩擦行为。见“User-defined

interfacial constitutive behavior,” Section 22.1.5，有更多信息是关于更一般定义表面间完全机械作用的接触面，包括法向和切向摩擦行为。

Input File Usage: *FRICTION, USER, DEPVAR=n, PROPERTIES=p

If p properties are specified, p data items

should be given on the data line.

ABAQUS/CAE Usage: Interaction module: contact property editor:

MechanicalTangential Behavior: Friction

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