Free-size optimization as part of the 3 phase composite structure optimization.
Hello, I am currently practicing 3-phase optimization of a simple laminated model—a flat plate under bending—where my layup sequence is as follows: 0/-45/45/90/45/-45/0. All plies have the same thickness, and I want to carry out the optimization following the 3-phase process described in Altair. However, I am facing several issues during the first phase:
a) My first issue arises when attempting a free-size optimization to minimize compliance. For this, I use a zone-based optimization, manually defining zones via sets in the DSIZE card (my goal is for all the elements in my flat plate model to have the same thickness for each ply bundle created). I create a set containing all the elements and introduce it in the "manual group" option. The problem is that, according to the .hist file, the compliance has reduced as expected, but the ply thickness has not changed. When performing a free-size optimization, shouldn’t the thickness be modified to reduce the compliance of my structure?
b) My second question is whether, once this is resolved, I could use the TSAI-Hill response for each ply to minimize it, or if it would be better to include this response later during the shuffle phase.
Answers
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- a) free-size changes the ply/elment thickness individually, at the element level, not at the laminate itself. You should have each element/ply with a different thickness. If you open HyperView with your _des.h3d file, you should see one of the results as thickness, and this should show you along the iterations the design changes.
- b) I'd include the ply failure response probably on phase 2 or 3. At phase 1, you're probably using SMEAR so stacking squence is not taken into account yet, so to speak
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Yes, i'm agree with you about using tsai-hill at the second and third phase, because, as you say, i am using SMEAR, so i am not taking in to account the failure values due to the stacking sequence and thus de coupling of bending and extensional efforts; so, i think it is a good option to modify the thickness of the ply bundles created, by minimizing the compliance (deformation energy); but, answering the first question; Mayby, once i have a distribution of thickness along the elements, Could i use the Ply Smoothering Tool to give constant ply thickness, per orientation? This is a constrain that i have; Summarizingl, i want to obtain a value of optimal thickness per orientation, once i have obtain the results of minimizing the Compliance.
Best Regards, Pablo
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Altair Employee