Do you mean this: Perturbation parameter for the static step ?
It’s not that useful to be honest because it forces full linearity of a static step and subsequent steps are independend of each other. In Abaqus, it’s used mostly for linear load cases.
Yes - that was the prior discussion/finding.
I didn’t realize linearity would be enforced. Interesting.
This sounds more like application for import functionality in Abaqus (transferring the deformed mesh with material state between the analyses). In CalculiX, you can only manually reuse the deformed meshes.
However, with multiple nonlinear general static steps (where the state of the model from the end of one step is used as the base state in the second step), boundary conditions and loads that can be activated/deactivated within each step and controlled by amplitudes, this should be doable. Especially since you can even activate and deactivate elements and contact pairs with the custom *MODEL CHANGE keyword.
Yes - this seems plausible. I do not have Abaqus, only around the periphery. In terms of commercial codes, my familiarity has always been with ANSYS, COSMOS (well today “Solidworks Simulation” or whatever they call it now), and long ago, EMRC-NISA, which I see is still around today as just NISA.
Is this a path now using Keywords I could take? the first delving into that has been this project with hyperelasticity definitions, so admittedly, I am really new to that.
Indeed, force control often leads to non-convergence of nonlinear analyses. So it’s advised to use displacement control instead whenever possible (you can always adjust it based on the reaction forces or follow it with force control step). For preload as well.
On force control … yes, we’ll aware of that and I usually do use displacement control. I have made force control work at times with small displacements, which is where I was coming from thinking about it as a 3rd step since the bulk of the displacement would be “baked in” already in the first two steps. But if not, I would resolve to hold down the two split surfaces, which is where the washer would contact the top face, and let it move elsewhere. I would have to forego the ability to look specifically at the screw however within the same analysis.
A giant challenge I am facing here is the parts are all plastic, and the screws are thread forming. There is very little to no guidance on flange gaskets and covers pre-load of fasteners for the joint in cases like this. ASME guidance is strong for UNC/UNF/etc fasteners to do this sort of joint, with metals, happy linear elastic materials. So if I cannot simulate the screw joint together with it, I’ll have to do that separately. That’s fine if I land there. Just basically making this up as I go 