Topology optimization with optistruct objective minimizing compliance

mohajerb@uwindsor.ca
mohajerb@uwindsor.ca Altair Community Member
edited October 2020 in Community Q&A

In topology optimization problems with objective of minimizing compliance, we minimize the compliance which means the maximum deflection is decreased in the optimized structure. Then why the stress increases?

Is the optimized structure (minimized compliance) really stiffer than the original structure? How can we justify this increase in stresses?

I don't understand how the displacement decreases, stress increases and stiffness is maximized.

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Answers

  • Rahul_P1
    Rahul_P1
    Altair Employee
    edited March 2015

    have you used a stress constraint? you can do this using the topology panel itself i.e. within the dtpl card. note however 

     

    It is not recommended to use the global stress constraint along with a mass/volume constraint. The constrained mass/volume may not allow the stress constraint to be satisfied.

    The stress constraint definition in a topology optimization is a global constraint and does not target local stress concentrations. These areas can be addressed subsequently through size, shape, and free shape optimization or a combination thereof. Artificial stress concentrations are filtered out during topology optimization with stress constraints. These include regions around rigid connections, concentrations due to hard geometric features such as corners, etc.


  • mohajerb@uwindsor.ca
    mohajerb@uwindsor.ca Altair Community Member
    edited March 2015

    Thanks for your reply. No I haven't used stress constraint. I have used volume fraction constraint. I have limited the upper bound of volume fraction and the objective is minimizing compliance. I don't understand the relation between this decrease in displacement and increase in stress. Is that something related to shape functions? What is the theory behind that?

  • tinh
    tinh Altair Community Member
    edited April 2015
    Altair Forum User said:

    Thanks for your reply. No I haven't used stress constraint. I have used volume fraction constraint. I have limited the upper bound of volume fraction and the objective is minimizing compliance. I don't understand the relation between this decrease in displacement and increase in stress. Is that something related to shape functions? What is the theory behind that?

     

    Hello

    to reduce displacement (reduce compliance), we have to increase inertia moment of section by distribute material further from neutral axis

    but stress also increases by distance from neutral axis (bending stress at neutral axis is 0). That is the theory you can find in your engineering book

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