Im running a study where I am accelerating a piston in a bore with a spring connector. The piston eventually hits a stop and I want to calculate the resulting impact forces. The issue I am having is with the spring connector. I notice when I have it in the model I get an error about stiffness on an element that is higher than the total elements I have in my solid mesh. I set up a simple non-linear dynamic model of two masses with a spring in between and it seams to solve fine. When the spring connector element is enveloped by another part (like a spring in a bore) the solver fails, even though the elements are not overlapping. I tried this in my simple two mass model and noticed when I raised the side walls of the larger mass to envelope the spring (but still not overlap it in volume), I get the same error.