Learning Forum

[maverick007]

Hello everyone,

I am running 3 deep drawing simulations with different punch and drawig edge radius. Two of the simulations converged without much difficulties but the third one isn't converging. In the two simulations which converged without much of a hassle, I saw a certain pattern in force convergence where the criterion increased from two digit number to a 6 digit number. I am not able to understand how this happened or how can I achieve this again for the simulation I am stuck on. I keep getting 'solution failed to converge' error after 10-12 hours of running the simulation.

I am using weak springs, MPC contacts, large displacements on, initial contact results dont show gaps, force is applied gradually in 5 steps and a direct solver is used in all of the simulations.

Please have a look at the pictures of the convergence criteria and also the model.

I am stuck on this problem since last 1 month and I don't know how to proceed. Please help!

[Erik Kostson]

I would start by using a remote displacement rather than a remote force to push it down. This will make convergence easier.
You will get the applied force in the end of the analysis by looking on the force reaction result of the applied remote displacement.
If you still have issues, attach your problematic model ( wbpz model) and someone might be able to look at it.

All the best
Erik

[maverick007]

Hi Erik
Thank you for your reply. I am trying it now.
And do you have any idea why the force criterion increased and accelerated convergence in the other simulations which had the same boundary conditions? The only thing which varies here is the drawing edge and punch edge radius.

with regards Maverick

[Erik Kostson]

Hi

The only thing I can think of is that the contact at that point changes and we get much higher forces in the parts hence the criteria changes. See below where a frictional contact becomes active in the last iteration.

All the best

Erik