22.1.4 - Frictional - behavior - - 摩擦行为(3)

coefficients can be functions of contact pressure, temperature, and field variables.

在默认模型中，静摩擦系数对应零滑移率给出的值，动摩擦系数对应最大滑移率给出的值。静动摩擦系数间的转换定义为给出的中间滑移率的值。在该模型中静动摩擦系数可以定义为接触压力，温度和场变量的函数。

ABAQUS also provides a model to specify a static and a kinetic friction coefficient directly. In this model it is assumed that the friction coefficient decays exponentially from the static value to the kinetic value according to the formula:

ABAQUS还提供直接指定动静摩擦系数的模型。在该模型中假定摩擦系数从静摩擦系数指数衰减到动摩擦系数，依据的公式：

where is the kinetic friction coefficient, is the static friction coefficient, is a user-defined decay coefficient, and is the slip rate (see Oden, J. T. and J. A. C. Martins, 1985). This model can be used only with isotropic friction and does not allow dependence on contact pressure, temperature, or field variables. There are two ways of defining this model.

其中，是动摩擦系数，是静摩擦系数，是用户定义衰减系数，是滑移率（见Oden, J. T. and J. A. C. Martins, 1985）。只有各向同性且不与接触压力，温度和场变量相关的摩擦才能使用该模型。

Providing the static, kinetic, and decay coefficients directly 直接规定静动和衰减系数

You can provide the static friction coefficient, the kinetic friction coefficient, and the decay coefficient directly (see Figure 22.1.4–2). 你能直接规定静动和衰减系数（见图Figure 22.1.4–2）

Input File Usage: *FRICTION, EXPONENTIAL DECAY

, ,

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

MechanicalTangential Behavior: Friction

formulation: Static-Kinetic Exponential Decay: Friction, Definition: Coefficients

Figure 22.1.4–2 Exponential decay friction model.

Using test data to fit the exponential model 使用试验数据拟合指数模型

Alternatively, you can provide test data points to fit the exponential model. At least two data points must be provided. The first point represents the static coefficient of friction specified at , and the second point, (, ) (shown in Figure 22.1.4–3), corresponds to an experimental measurement taken at a reference slip rate . 同样，你可以提供试验数据点来你和指数模型。最少需要提供两个数据点。第一个点表示指定在的静摩擦系数，第二点（, )（见图Figure 22.1.4–3）对应于在参考滑移率的试验测量值。

Figure 22.1.4–3 Exponential decay friction model specified with test data points.

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 …… 此处隐藏：3633字，全部文档内容请下载后查看。喜欢就下载吧 ……