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How to determine volume fraction value

User: "e_taralom"
e_taralom
Altair Community Member
Updated by 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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    User: "Altair Forum User"
    Altair Forum User
    Altair Employee
    Updated by Altair Forum User

    Hello,

     

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

     

    Benoit

    User: "Rahul_P1"
    Rahul_P1
    Altair Employee
    Updated by 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

    User: "e_taralom"
    e_taralom
    Altair Community Member
    OP
    Updated by e_taralom

    thank you for your help.

    User: "Merula_20758"
    Merula_20758
    Altair Community Member
    Updated by 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

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