Ummm, something is weird.
I’m doing a simple stress analysis of a surface under the self-weight.
I’m using membrane elements instead of shell elements to neglect bending moments.
I think the analysis was converged correctly, but the principal stresses draw radial bands, and between the bands, compression and tension forces show up alternately.
I don’t know I explained the issue well, but the below attached image shows the problem.
The same band appear when I used shell elements instead. And there is no big difference between linear/nonlinear analyses.
kiwi3d -shell3.gh (155.5 KB)