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发表于 2011-8-5 08:54:40
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来自 香港
感谢拉布索思的回复。
由于问题本身与模型无关,我也就没有给出具体模型,计算是静力的,有一点比较特殊的接触面是 Gasket 单元,Inter195. 目标面是法兰 solid186。(这可能是另外的一个话题了,这里我就不讨论了)
你说的一下comand neqit=100,设小子步等等,我都试过的,问题还是一样。
output我也详细查看过,我自己的理解和你差不多:是除了力控制,他还根据穿透和接触状态是否稳定来判据. 其中的2个参数就是FTOLN , TNOP
The pure Lagrange multiplier method enforces zero penetration when contact is closed and "zero slip" when sticking contact occurs. The pure Lagrange multiplier method does not require contact stiffness, FKN and FKT. Instead it requires chattering control parameters, FTOLN and TNOP. This method adds contact traction to the model as additional degrees of freedom and requires additional iterations to stabilize contact conditions. It often increases the computational cost compared to the augmented Lagrangian method.
Chattering Control Parameters
The Lagrange multiplier methods (KEYOPT(2) = 3, 4) do not require contact stiffness, FKN and FKT. Instead they require chattering control parameters, FTOLN and TNOP, by which ANSYS assumes that the contact status remains unchanged. FTOLN is the maximum allowable penetration and TNOP is the maximum allowable tensile contact pressure.
The behavior can be described as follows:
If the contact status from the previous iteration is open and the current calculated penetration is smaller than FTOLN, then contact remains open. Otherwise the contact status switches to closed and another iteration is processed.
If the contact status from the previous iteration is closed and the current calculated contact pressure is positive but smaller than TNOP, then contact remains closed. If the tensile contact pressure is larger than TNOP, then the contact status changes from closed to open and ANSYS continues to the next iteration.
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