number of equilibrium iterations exceeded

[icetears]

thread569-272678

Hi ,
Can anyone help me with the past issue described in this thread:
thread569-272678

Many thanks

 

[kan123]

If you have significant plasticity, a sudden turn around in load can sometimes cause a problem. (I haven't seen this error message before, but I work in APDL.) Try a load of 1199 for your second load step before going to 0 in the next one. Make sure there are a sufficient number of substeps in the first and last load steps to reasonably track the nonlinear behavior. If you still have trouble at the turn-around load step, you can loosen the convergence criteria for that one, then tighten it back up for subsequent steps.

 

[icetears]

Hi kan,

Many thanks for your suggestions. I've made some research and finally I've noticed that it is not necessary to retry the load to zero to achieve plastic strain. Usually, plastic strain is almost the same in the last load step like the step where the load is applied. I could insert 90% of load in the last load step.
You said something about " loosen convergence criterion".
How can I make this? Is there an APDL command to do this?
I have experience only with Workbench.

Thank you once again

Best regards

 

[kan123]

The APDL command to control convergence criteria is CNVTOL. You can loosen the tolerance (TOLER) or change the error norm (NORM).

 

[SFLM]

icetaers,

Loosening the convergence tolerance criterion is something that you should never do according to ANSYS courses and to what I understand of FEA.

So, instead, you can apply the same load in the opposite direction to end up with zero resultant force. Or you can use displacement instead of force.

Could you clarify a little bit the way you applied the load in WB? You can either deactivate the LS or use 0. A snapshot would be great.

Cheers