access to not converged data in iterations

[ulman]

Hi,
I am doing a simple plasticity simulation on large deformations using UMAT.
The simulation is not converging even for very small time steps.

With URDFIL it is possible to access data for each increment (equilibrium).

Is it possible to access results (displacements for instance) for each iteration in an increment, so for the not converged data in the Newton-Raphson iteration scheme?

Indeed, I would like to code something like a routine which gives the unbalanced energy (displacement increments * (fext-fint) ) for the iterations.

Kind regards.

[Jorgen]

You can always print out the displacements, etc, from within the UMAT subroutine. That is still one of the best ways to debug a UMAT.

If you don't get convergence, then your caliculated stress or the Jacobian are likely wronge. I suggest that you print out the values that you calculate. That way you can verify that they are what you expect.

-Jorgen

[ulman]

Hi, thanks. I didn't know that I can print out the displacements directly in the UMAT subroutine. I thought that you only have access to data which are passed to UMAT from Abaqus. I will have a look on that in the manual, however, if you have time, please give me a hint, which function or routine i have to search for.
Regards.

[Jorgen]

My mistake, you don't have access to the displacements. But you can print and examine any of the other input (and output) variables.

-Jorgen