I’m currently using Nlgeom with the material having plastic properties. But I assume this is only valid up to a certain compression or material displacement? Think of a plastic O-ring under a cap. For example the oil plug in your car. A plastic material like copper/soft aluminum is used to create the seal between the screw and the oil pan. Except in my application, I start with a round O-ring and I want to end in a flat, thin ring of the same volume. Is this something that Mlgeom can get me to? or am I barking up the wrong tree?
Nlgeom only accounts for geometric nonlinearity. Material model is reponsible for a separate type of nonlinearity. If you want to simulate irreversible deformation of a metal then you have to use plasticity with proper data. Other material models like hyperelasticity are meant primarily for different types of materials and deformations.
In such a simulation problems might be caused mainly by mesh distortion and volumetric locking. Unfortunately, CalculiX (unlike Abaqus) doesn’t have special features to deal with those issues. However, incompatible mode elements might help with some of them.
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This is great feedback. I didn’t want to develop some big model and then find out that the real thing doesn’t really behave like that. I’ve been observing that the software does get stuck if it hydrolocks or if the mesh between parts gets too distorted.