I always thought PrePoMax could not handle multi-step analysis with the previous step being the initial condition for the next one, and even check other threads such as this one and that as well.
However, I set a two-step analysis (static with plasticity, 10 increments in each step) in one joint, and the second step’s first increment maintains the final state of the first step!
I double-checked the input file, all steps have “OP=NEW” in both boundary, Cloads, and Dloads. How is that even possible? I cannot attach the file I’m using, but I’ll create a simpler model and try to recreate this. Did someone ever have something similar?
Yes, that’s how it works in Abaqus and CalculiX. Non-perturbation steps use the state of the model from their predecessors. It’s visible when plasticity is involved. The OP parameter is just to control the boundary conditions, loads and other step-dependent features. When set to NEW (always in PrePoMax), all those features that are supposed to be still working have to be redefined in each step. The remaining ones are removed. When set to MOD, they are carried over automatically and there’s no need to respecify them. You can modify them or add new ones though. But this parameter doesn’t affect the material state.
It makes sense. I would like to use the same input file to run multiple plasticity analyses (more than one load case), so I need one input file for each, correct?
I decided to use OP NEW since exporting the model to the .inp file is easier and more consistent. What is seen in the model tree is also written in the .inp file. If I would use MOD, the model tree and the .inp file would not be consistent for a novice/easy user of PrePoMax. It is hard to understand the settings of the 5th step by looking at the .inp file if MOD is used in all previous steps.