22.1.4 - Frictional - behavior - - 摩擦行为(4)

边界剪应力面（见图Figure 22.1.4–5）是–空间中以和

为极值点的椭圆。椭圆大小随接触面间接触压力变化而变。滑移方

向

与边界剪应力面正交。

Figure 22.1.4–5 Critical shear stress surface for the anisotropic friction model.

The friction coefficient can depend on slip rate, contact pressure, temperature, and field variables. By default, it is assumed that the friction coefficients do not depend on field variables.

摩擦系数可以决定于滑移率、接触压力、温度和场变量。默认情况下，假定摩擦系数不决定于场变量。

Input File Usage: *FRICTION, ANISOTROPIC, DEPENDENCIES=

,

,

, , ,

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

MechanicalTangential Behavior: Friction

formulation: Penalty: Friction, Directionality: Anisotropic

If necessary, toggle on Use slip-rate-dependent data, Use contact-pressure-dependent data, and/or Use

temperature-dependent data; and/or specify the Number

of field variable dependencies in addition to slip rate, contact pressure, and temperature.

Preventing slipping regardless of contact pressure

防止滑移，不管接触压力多大

ABAQUS offers the option of specifying an infinite coefficient of friction (). This type of surface interaction is called “rough” friction, and with it all relative sliding motion between two contacting surfaces is prevented. ABAQUS/Standard uses Lagrange multipliers to enforce this constraint; ABAQUS/Explicit uses either a kinematic or penalty method, depending on the contact formulation chosen.

ABAQUS提供指定无穷大的摩擦系数选项（）。这种面相互作用称为“粗”摩擦，且不允许两接触面间有任何相对滑移运动。ABAQUS/Standard用拉格朗日乘子来加强这种约束；ABAQUS/Explicit用运动学或罚函数法，取决于所选接触方程。

Rough friction is intended for nonintermittent contact; once surfaces close and undergo rough friction, they should remain closed. Convergence difficulties may arise in ABAQUS/Standard if a closed contact interface with rough friction opens, especially if large shear stresses have developed. The rough friction model is typically used in conjunction with the no separation contact pressure-overclosure relationship for motions normal to the surfaces (see “Using the no separation relationship” in “Contact pressure-overclosure relationships,” Section 22.1.2), which prohibits separation of the surfaces once they are closed.

粗摩擦计划供间歇的接触使用； 一旦两表面接触且为粗摩擦，他们应该保持接触状态。在ABAQUS/Standard里，如果一接触的粗摩擦接触面开始分开，尤其是有大剪应力时，可能会导致收敛问题。典型的，在接触面的法向运动上联合使用粗摩擦模型与不分开的接触压力-过盈关系（见“Using the no separation relationship” in “Contact pressure-overclosure relationships,” Section 22.1.2），一旦表面接触，这样做就能阻止它们再分开。

When rough friction is used with the no separation relationship for hard contact in ABAQUS/Explicit specified with the kinematic contact method, no relative motions of the surfaces will occur. For hard contact in ABAQUS/Explicit specified with the penalty contact method, relative motions will be limited to the elastic slip and penetration corresponding to the inexact satisfaction of the contact constraints by the applied penalty forces. When softened tangential behavior is specified in ABAQUS/Explicit (see “Defining tangential softening in

ABAQUS/Explicit” below), the relative surface motions will be governed by the specified softening behavior.

在ABAQUS/Explicit中，当联合使用粗摩擦和硬接触、运动学接触算法和不分开关系时，接触面就不会出现相对运动。在ABAQUS/Explicit中，使用硬接触、罚函数接触算法时，相对运动将限于弹性滑移和侵彻，相当于不精确的满足应用惩罚力的接触约束要求。当在ABAQUS/Explicit中使用软切向行为时（见下面的“Defining tangential softening in ABAQUS/Explicit），指定的软行为将控制表面间的相对运动。

Input File Usage: *FRICTION, ROUGH

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

MechanicalTangential Behavior: Friction formulation: Rough

Shear stress versus elastic slip while sticking 粘着时，剪应力对弹性滑移

In some cases some incremental slip may occur even though the friction model determines that the current frictional state is “sticking.” In other words, the slope of the shear (frictional) stress versus total slip relationship may be finite while in the “sticking” state, as shown in Figure 22.1.4–6.

有时，尽管摩擦模型确定当前接触状态为“粘着”，但也可能会产生一些滑移。换句话说，在“粘着”状态，剪（摩擦）应力对总滑移量关系曲线的斜度可能是有限值，见图Figure 22.1.4–6。

Figure 22.1.4–6 Elastic slip versus shear traction relationship for sticking and slipping friction.

The relationship shown in this figure is analogous to elastic-plastic material behavior without hardening: corresponds to Young's modulus, and corresponds to yield stress; sticking friction corresponds to the elastic regime, and slipping friction corresponds to the plastic regime. A finite value of the sticking stiffness may reflect a user-specified physical behavior or may be characteristic of the constraint enforcement method.

上图显示的关系类似于没有热处理的弹塑性材料行为，相当于杨氏模量，相当于屈服应力；粘着摩擦相当于弹性状态，滑移摩擦相当于塑性状态。一个有限的粘着刚度值可能反映一中用户定义物理行为，也可能是强制约束法的特征。 Frictional constraints are enforced with a stiffness (penalty method) by default in ABAQUS/Standard and for the general contact algorithm in ABAQUS/Explicit; in this case the sticking stiffness will have a finite value. An infinite sticking stiffness, in which case the elastic slip is always zero, can be achieved with the optional Lagrange multiplier method for imposing frictional constraints in ABAQUS/Standard or with the kinematic constraint method (available only …… 此处隐藏：6001字，全部文档内容请下载后查看。喜欢就下载吧 ……