Non Convergence due to material failure or problematic contacts? Please HELP!!!
I am trying for over 6 months to model the post-cracking behavior of an ultra high performance concrete subjected to bending. After trying various suggestions that I found here in this community (solid65, microplane with elastic damage, menetrey-willam) I ended up using Drucker-Prager Model for Concrete as I can input stress-strain data obtained from experiments to describe the constitutive law of strain hardening ultra high performance concrete. From a quick look on the solver output I think the problem lies on the material ( "The material solution failed for element 21503 with material 1"). However, when I plot the Newton-Raphson Residual Forces it seems that the contacts between the prism and the supports or the supports and the steel bases are problematic. I changed set the stiffness to be updated after each iteration, but still nothing works. At the end of the day I want to be able to obtain the plateau and the descending branch on the Force-Midspan Displacement curve. Could someone please have a look on the attached model and help me? My deadline is approaching and I am in desperate need of help!!!