How to use an external excel file for topology optimization in optistruct as an objective?

I am not sure I follow all that you are trying to do but would a DRESP3 work for this?  It sounds like it would be a good fit.
https://2022.help.altair.com/2022.1/hwsolvers/os/topics/solvers/os/dresp3_bulk_r.htm

Using a Compose function might help.

https://2022.help.altair.com/2022.1/hwsolvers/os/topics/solvers/os/compose_function_for_dresp3_response_example_problem_r.htm

I am not sure I follow all that you are trying to do but would a DRESP3 work for this?  It sounds like it would be a good fit.
https://2022.help.altair.com/2022.1/hwsolvers/os/topics/solvers/os/dresp3_bulk_r.htm

Using a Compose function might help.

https://2022.help.altair.com/2022.1/hwsolvers/os/topics/solvers/os/compose_function_for_dresp3_response_example_problem_r.htm

Hi,

thank you for your answer.

Yes, I have read about the DRESP3 card. But the problem is, in the examples, the inputs of the DRESP3 card are always some internal (DRESP1) response, and the strain energy density of each element is not available as an internal response, only in the result files (.h3d files).

Sadly it cannot be calculated either, using equations because the stress and strain values cannot be obtained in the integration points as internal responses.

If somehow after each iteration during topology optimization, I can calculate from the h3d files my objective value and give it to optistruct to continue the optimization, that would be the solution. 

But surprisingly I cannot find any method or example for this. 

Hi,

thank you for your answer.

Yes, I have read about the DRESP3 card. But the problem is, in the examples, the inputs of the DRESP3 card are always some internal (DRESP1) response, and the strain energy density of each element is not available as an internal response, only in the result files (.h3d files).

Sadly it cannot be calculated either, using equations because the stress and strain values cannot be obtained in the integration points as internal responses.

 

If somehow after each iteration during topology optimization, I can calculate from the h3d files my objective value and give it to optistruct to continue the optimization, that would be the solution. 

But surprisingly I cannot find any method or example for this. 

Ok. I understand a little more the challenges you are facing.  I am not sure when the information for each iteration is written but it might not be available when the responses are calculated.  If that is the case I think you would have to try a HyperStudy approach (which may be the best option any ways).   If the information is available you could probably have dummy inputs into your DRESP3 and use your scripts to feed back in the right answer.  That is a big if though.

So using HyperStudy you would actually take out all the optimization setup and instead set those things up in HyperStudy.  I am not an export in HyperStudy but I know there is lots of information out there.  And you could post another question on the HyperStudy forum but to get you started here are 2 tutorials that may help.

https://2022.help.altair.com/2022.1/hwdesktop/hst/topics/tutorials/hst/tut_hs_1515_t.htm

https://2022.help.altair.com/2022.1/hwdesktop/hst/topics/tutorials/hst/tut_hs_1680_t.htm

Hope that helps.