topology optimization with multiple load cases

Hi Mike,

What is the objective and constraints you want to use?

So far I used min compliance as objective function and volume fraction as constraint

Hi Mike,

You can use Wcomp (Weighted compliance) and select all loadsteps along with volume fraction. This way you are considering all loadcases. 

Thank you!!

So I create the response 'weighted compliance' and, in my case of 5 load cases of equivalent importance, I set each weighting factor to 0.2, correct?

And then as usual in the objective I set minimize the weighted compliance, correct?

Thank you!

Mike,

See the equation below for WC, where W is the weight factor. 

If your weight factor is 0.2, the compliance considered for load case1 for example will be 0.2 times of actual compliance. 

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So if I want all the five load cases to have same weight, what should I set the weight factors to?

Set the weight factor to 1 

What if I want to minimize the mass as objective function? Is it possible to still add multiple load cases?

Mass response is subcase independent.

Thank you for your answers...last question.

What would be the best approach if I want to:

• minimize the volume of the model (or the mass) with multiple load cases and
• and as constraint use the static stress

Is there a possibility? Or how would you suggest to run the optimization?

Hi Mike,

Stress as a global response with mass or volume response is not recommended

from OptiStruct help:

It is not recommended to use the global stress constraint along with a mass/volume constraint. The constrained mass/volume may not allow the stress constraint to be satisfied.

To start of with, Try with Complinace as objective and volume fraction to get  a concept and further you can fine tune the design for stress and other parameters.

Perfect thank you very much!!

Hi,

I have a design that is made of several 1D bar elements (about 15) of circular cross section.

I now want to perform a size optimization on the cross section radius of these beams.

I have multiple load cases (3)!

I would like to minimize the mass and subject the stress.

How should I do that?

Thank you

Hi Mike,

You can select loadsteps when you create Stress constraint.