Chattering classes

[corus]

In a contact analsysis the results show 1 node opening and closing with no convergence of the results (so-called chattering). I've tried automatic tolerances, didn't work, I've tried setting maxchp=2,uerrmx=0.01, didn't work, I've tried using a soft exponential contact, didn't work, I've tried combinations of the 3, didn't work.
Any ideas on how to get convergence?

 

[barryodonnell]

Hi

Try *STATIC, STABILIZE in conjunction with the *CONTACT CONTROLS, AUTOMATIC TOLERANCES option, this has helped me in the past. If you have access to bersion 6.4, I have had some success with the new Augmented Lagrangian algorithm with models that had difficulty converging in 6.3 (this can be invoked with the following in the surface interaction definition:
*SURFACE BEHAVIOR, AUGMENTED LAGRANGE

Barry

 

[corus]

Thanks Barry, I don't have 6.4 yet but I'll see if the *static option is available in 6.3 and try that.

corus