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MAC Optimization between two models.

How can I optimize the MAC between two models (FE vs. Test) to align the frequencies between those models?

I am trying to use the material properties of the FE model as design variables and the frequencies as responses, then constrain the frequencies. The problem is that one has to use an objective, and that objective is limited to Min, MAX ...

Any thoughts?

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OptiStruct

v2021.1

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Adriano Koga_20259

You can try using the System Identification response. (DSYSID).

once you have created a System Identification response, you need to specify which responses need to be controlled, in your case freq1, freq2, freq3, ...

These will be selected as RID.

For each of then, you can specify a target value (T).

Let's say FREQ1, target 100Hz., FREQ2, target 150Hz. ...

Then this DSYSID will be pointed as your objectice>> minimize DSYSID

What it does is to build a Least Squares minimization problem (take a look at OptiStruct help for DSYSID):

Community-Pasted-Attachment-1613147775537.png

Numair

Hi Adriano,

Thank you for your response. Do you have an example? I could not get it to run. It seems you need one DSYSID card to minimize as objective, but you cannot call all the responses from that card!

Numair

Hi Adriano,

Thank you for your response. Do you have an example? I could not get it to run. It seems you need one DSYSID card to minimize as objective, but you cannot call all the responses from that card!

I guess, I found it. The number in circle needs to be changed to 4. And there has to be 4 responses.

Numair

Can you have constraints on the frequency, or is that satisfied by the DSYSID?