Hi David,

On 02/22/2013 06:40 PM, David Mashburn wrote:

Thanks Robert, that already helps a lot. Glad to know it is a non-trivial question.

We are actually trying to cross-check some analytical solutions, so I would like to get this to work at least to some degree of confidence.

Do you think that those would be a good tests to add to sfepy test suite?

I've tried swapping out a simple neohookean system with bulk penalty and all that like in the example. A warp violation seems to be causing an exception after one iteration with a nominal amount of stress.

I've been digging through the nonlinear solver's parameters and can't find a way to shrink the initial step size. The other work-around I can think of is to use a time stepper to gradually increase the stress. Is there another/easier way to do this?

Yes, this is the way to do it - use time stepping to increase the load gradually. I am not aware of other ways. In nonlinear analysis with the Newton solver, a good initial guess is required.

Also, is it normal for a system with a fairly large deformation to throw a warp violation and then still recover afterwards (if so, then maybe this exception is a bug?)

How does it recover? I assume it just throws off the warped solution and the nonlinear iteration does not converge, right?

r.