22.1.4 Frictional behavior 摩擦行为

An additional data point can be specified to characterize the exponential decay. If this additional data point is omitted, ABAQUS will automatically provide a third data point, (, ), to model the assumed asymptotic value of the friction coefficient at infinite velocity. In such a case is chosen such that

.

可以指定额外数据点来表征指数衰减。如果省略这些额外的数据点，ABAQUS会自动提供第三数据点(, )来模拟假定的在无限大速度的摩擦系数的渐近线值。这样，选择

使得

。

Input File Usage: *FRICTION, EXPONENTIAL DECAY, TEST DATA

,

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

MechanicalTangential Behavior: Friction

formulation: Static-Kinetic Exponential Decay: Friction, Definition: Test data

Using the optional shear stress limit 使用剪应力极限选项

You can specify an optional equivalent shear stress limit, , so that, regardless of the magnitude of the contact pressure stress, sliding will occur if the magnitude of the equivalent shear stress reaches this value (see Figure 22.1.4–4). A value of zero is not allowed.

你可以指定等效剪应力极限选项，从而使得如果等效剪应力大小达到该值，不管接触压应力多大，都将发生滑移（见图Figure 22.1.4–4）。该值不允许设为零。

Figure 22.1.4–4 Slip regions for the friction model with a limit on the critical shear stress.

This shear stress limit is typically introduced in cases when the contact pressure stress may become very large (as can happen in some manufacturing processes), causing the Coulomb theory to provide a critical shear stress at the interface that exceeds the yield stress in the material beneath the contact surface. A reasonable upper bound estimate for

is

,

where is the Mises yield stress of the material adjacent to the surface; however, empirical data are the best source for . 为了防止当接触压应力可能变得非常大，导致库仑理论产生的接触面上的临界剪应力值超过接触面下材料的屈服应力，通常引入剪应力极限。的一个估计的合理上界是数据是

，其中

是接近表面的材料的Mises屈服应力，然而经验

最好的来源。

Input File Usage: *FRICTION, TAUMAX=

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

MechanicalTangential Behavior: Friction

formulation: Penalty or Lagrange Multiplier: Shear Stress, Shear stress limit: Specify:

Limitations with the shear stress limit 剪应力极限的局限性

In ABAQUS/Explicit a shear stress limit cannot be used when a contact pair uses a node-based surface as one of the surfaces.

在ABAQUS/Explicit中若接触对用基于节点的面作为一个接触面，就不能使用剪应力极限。

Using the anisotropic friction model in ABAQUS/Standard 在ABAQUS/Standard中使用各向异性摩擦模型

The anisotropic friction model available in ABAQUS/Standard allows for different friction coefficients in the two orthogonal directions on the contact surface. These orthogonal directions coincide with the slip directions defined in “Contact formulation for ABAQUS/Standard contact pairs,” Section 21.2.2; and those for contact elements are described in the sections defining contact modeling with those elements. The orientation of the slip directions cannot be changed.

ABAQUS/Standard中可用的各向异性摩擦模型允许在接触表面两个正交方向有不同的摩擦系数。这些正交方向与滑移方向（“Contact formulation for

ABAQUS/Standard contact pairs,” Section 21.2.2）相符；在定义接触模拟那些单元的截面里描述接触单元里的滑移方向

If you indicate that the anisotropic friction model should be used, you must specify two friction coefficients, where is the coefficient of friction in the first slip direction and is the coefficient of friction in the second slip direction.

如果你需要使用各向异性摩擦模型，你必须指定两个摩擦系数：是第一个滑移方向的摩擦系数，是第二个滑移方向的摩擦系数。

The critical shear stress surface (see Figure 22.1.4–5) is an ellipse in – space with the two extreme points being

and

. The size of this ellipse will change with the change in

contact pressure between the surfaces. The direction of slip, orthogonal to the critical shear stress surface.

, is

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