Model simplification for topology optimization

Hello,

I have a question about model simplification. In the attached sketch you see  my model in simplyfied form. The black solid is very large and complex. So it takes a lot of time to optimize the model.

Is there a way replace the black solid with something like a spring? I imagine to do one analysis at the beginning, reduce the model and optimize the model without the black body.

But i dont know how to implement this. It would be great if there is any solution.

Thank you very much

Andreas

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