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How to determine volume fraction value

e_taralom

Hi all,

I'm new at optimization. I have been trying to optimize an automobile part with aid of tutorials.

I set up the model. I specified objective as minimization of weighted compliance and constraint as volume fraction.

But i couldn't decide value of volume fraction. Honestyl i didn't even understand what volume fraction is. Can anyone help me about this issue?

Best Regards

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Altair Forum User

Hello,

Volume fraction is the ratio between volume of design space at iteration i on initial volume of design space.

Benoit

Rahul_P1

Formulation for volume fraction:
Volume fraction = (total volume at current iteration – initial non-design volume)/initial design volume

we many times use 0.3 to start with , which means 30% of the 'design space' volume will be retained.

In OS help , see -

Altair OptiStruct > User's Guide > Design Optimization > Responses:

Internal Responses

e_taralom

thank you for your help.

Merula_20758

Finding the optimal value for your volumefrac is somewhat of a iterative procedude. So use 0.3 as a starting point and go from there....

maybe do a vf dconstraint of 0.4 and 0.2 and see, what changes.

Best Regards,

Merula