I am running a displacement-control simulation to a knee model to measure the contact stresses on the cartilage. I followed the same boundary conditions that was defined in the knee model developed by the Cliviland clinic group (Dr.Erdemir). Specifically, I used a sliding interface between the two cartilages with high penalty and facet-on-facet contact size. I aslo defined low densities for all components and used dynamic analysis. However, the solution did not converge and produced a bunch of negative jacobians at the contact elements. I am using FEB 2.5.

Can anyone advise?

You may downlaod the feb file from this link: https://drive.google.com/open?id=18z...Y7UVv_E6IsOhOs

Thank you,