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Optimization: Thickness decrease on size optimization

Hi,

I am trying to perform an monocoque optimization. I make the first step, freesize optimization, and the maximum thickness on last iteration is 9.5.

After changing control card to SZTOSH, update the laminate on desvar and also introduce the manufacture thickness, I run size optimization. However, the element thickness decrease instead of keep almost the same but with a multiple number of the manufacture thickness.

I have realized that the first iteration on size has the thickness of the last iteration on freesize (9.5) maybe is something wrong on the setup.

Could anybody help me please?

Thank you

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Adriano_Koga

did you change the optimization setup from free-size to size? In terms of responses or contraints?

Remember that free-size is a conceptual optimization only, and the most important thing from it should be 'where' to place fiber layers, and not exactly how thick.

Thickness should be given by size optimization, including your more detailed deisgn criterea.

It is normal to change thickness values from one to the ohter.

You should look if your design and manufacturing constraints are respected in the end.

Dani_20

Yes, I have changed to composite size and update the new laminate. I do not modify neither responses nor constraints because are the same than on free size.

I thought that the element thickness have not to change because I have followed a tutorial made by Altair of carbon fiber monocoque and the thickness of the size optimization was almost the same than on free-size. However, I have checked the upper weight constraint and are respected.

So I understand that the process is correct and the optimization is also correct.

Thanks for the information, I do not know how exactly an optimization works.

Adriano_Koga

If your responses and constraints are similar, I would expect them to be close, but not necessarily the same as free-size.

In this case the design variables are different, so the solver needs to make decisions based on different scenario than before. In order to change something, it needs to change a bigger area than before.