Complex PLA Model Static Analysis

General Questions
1

Could someone please take a look and let me know if I am on the right track? I am a designer, am new to PrePoMax/mechanical engineering in general.

Recently I made a model for an installation and want to do a test in PrePoMax to see how it stands in general. After some research, this is what I ended up with:

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Material is wood fused PLA and has 3 properties assigned: elasticity, plasticity, density. Numbers are given by manufacturer. The “light material” is lighter because it’s hollow inside, so I give it a smaller density to simplify the problem. Step is static with iterative cholesky solver, 5s time period, 1s initial time increment, 1e -6s min increment. The goal of analysis is to see if there’s any point that has very high stress - something approximate is good enough, the model is already a simplified version of the original.

Besides the settings above, I’ve also tried other solvers, increments, or a model that is one single piece instead of 4 pieces, and I never get a result that converges. Anything I am missing?

2

Gravity load can be assigned to the whole model. If individual parts have different mass, it will be accounted for automatically. When it comes to the solver, default PaStiX or Pardiso should be sufficient. Make sure that all parts are properly connected by running a frequency analysis. Then you can try running it without plasticity since this can be the source of non-convergence as well. Also, try without Nlgeom if it’s already enabled.

3

Beauuuutiful model.
Keep in mind that NLA divergence doesn’t always mean the setup is “wrong”. Specially if it happens on a model that has been running well for some time. Your tree is under compression, and you have some thin tree roots on the base that might be buckling.
I would complement FEAnalyst excellent proposal about checking the contacts with an additional Buckling analysis checking those thin base roots, (Specially if they are hallow).
It’s amazing how nature build light lattice structures without even knowing what they are.