Hello Dr. Bergstrom,

I found why the multi-element test quits. The codes terminates when the F matrix (defgradNEW) of one element becomes [1 0 0, 0 1 0, 0 0 1] which means no deformation at all. Then stress of this element becomes zero and singularity occurs.

How could that happen: during simple tension, the deformation of one of the element is identity? When I introduce a artificial perturbation (1d-8) to F matrix to avoid the sigularity, then it can be completed, but the yield point was jumped. BTW, I am modeling Argon model for PC. However the data for one-eleemt and four-elemet test are very good, since no elements is assigned to be zero deformation during the calculation by ABAQUS.

Any suggestions for this kind of problem?

Thanks.

Best,

Yaning