Converging forces, but diverging displacement
I'm running a non-linear, static structural model (plasticity, large deflections and frictional contacts), but it won't solve for fine meshes. The model consist of a plate fixed at one end, and bolted to a weight (represented as a solid block with planar face). Forces are applied to the weight. The residual forces are below the criterion, but the displacements are diverging at roughly 70% of max load, and the solution fails due to highly distorted elements. I've verified through hand calculations and a linear analysis that the load is appropriate for the structure. I'm not expecting large plastic deformations at all, just some plastic strain at corners and around bolt holes.
The highly distorted element is close to the bolt hole, and this is where I find the maximum residual force as well. However, there is no contact between this element and the bolt, so I'm surprised to find a large residual here. There is only the frictional contact with the weight, but as seen in the contact status, the status is "near" when the solution fails.
Any thoughts on what could be causing this issue?
Convergence plot (Step 1 is bolt pretension, step 2 and 3 is gradually applying the loading):