改善ANSYS中接触分析收敛性的几项设置

1、过粗的网格尺寸可能导致收敛困难。

2、过大的接触刚度可能引起总刚度矩阵的病态

http://s16/mw690/9f5beef7gdb41d823c1ff&690

3、拉格朗日法相对于罚函数法而言，不易引起病态条件。

http://s5/mw690/9f5beef7gdb41d2c1d6b4&690

4、接触刚度的更新方式可能有影响

  接触法向和切向刚度有5种更新方式，如下：

• KEYOPT(10) = 0, the contact stiffness will be updated at each load step if FKN or FKT is redefined by the user. Stiffness and other settings (ICONT, FTOLN, SLTO, PINB, PMAX, and PMIN) are averaged across contact elements in a contact pair. The default contact stiffness is determined by underlying element depth and material properties.

      FKN or FKT 在每个荷载步内更新，刚度值和其他数值均为平均值。

• KEYOPT(10) = 1 (covers KEYOPT(10) = 0), the normal contact stiffness will be updated at every substep based on the mean stress of the underlying elements from the previous substep and the allowable penetration, FTOLN, except in the first substep of the first load step. The default normal contact stiffness for the first substep of the first load step is the same as described for KEYOPT(10) = 0. If bisections occur in the beginning of the analysis, the normal contact stiffness will be reduced by a factor of 0.2 for each bisection. The tangential contact stiffness will be updated at each iteration based on the current contact pressure, MU, and allowable slip (SLTO).

     FKN 在每个子步内更新， FKT 在每次迭代内更新，刚度值和其他数值均为平均值。

• KEYOPT(10) = 2 (covers KEYOPT(10) = 1), the normal contact stiffness will be updated at each iteration based on the current mean stress of the underlying elements and the allowable penetration, FTOLN, except in the very first iteration. The default normal contact stiffness for the first iteration is the same as described for KEYOPT(10) = 0. If bisections occur in the beginning of the analysis, the normal contact stiffness will be reduced by a factor of 0.2 for each bisection. The tangential contact stiffness will be updated at each iteration based on the current contact pressure, MU, and allowable slip (SLTO).

      FKN 在每次迭代内更新， FKT 在每次迭代内更新，刚度值和其他数值均为平均值。

• KEYOPT(10) = 3, same as KEYOPT(10) = 0, except stiffness and settings are not averaged across the contact elements in a contact pair. If bisections occur in the beginning of the analysis, the normal contact stiffness will be reduced by a factor of 0.2 for each bisection.

     同KEYOPT(10) = 0，只是刚度值和其他数值不为平均值。

• KEYOPT(10) = 4, same as KEYOPT(10) = 1, except stiffness and settings are not averaged across the contact elements in a contact pair.

     同KEYOPT(10) = 1，只是刚度值和其他数值不为平均值。

• KEYOPT(10) = 5, same as KEYOPT(10) = 2, except stiffness and settings are not averaged across the contact elements in a contact pair.

     同KEYOPT(10) =2，只是刚度值和其他数值不为平均值。

    In most cases we recommend that you use KEYOPT(10) = 2 to allow the program to update contact stiffnesses automatically.

    一般情况下，建议使用KEYOPT(10) = 2 ，允许程序自动更新接触刚度。

5、某些时候使用不对称求解可改善收敛性

http://s15/mw690/9f5beef7gdb41de301d2e&690