I’m having an issue with the visco-plastic material model specifically when using the 2D box geometry model. I have the model set to use default values for the material model and setting the strain weakening mechanism to none, with the viscosity averaging scheme set to harmonic and the viscous flow law as composite. The model fails after the first time step showing this error.
However, the model works if the flow law is diffusion or dislocation. It also works if I use a 2D cylindrical geometry with the exact same visco plastic material model. I’m assuming the issue is from the difference in geometry but I’m not sure how to get it to work.