I did two material topology optimization and when I look the output there is three color so three material.

Oğuz Kalaycı
Oğuz Kalaycı Altair Community Member
edited June 2023 in Community Q&A

If the blue one is the represent the empty, how can I reassign material to empty elements. (Constrains; MassFrac upper bound is 0.4 and minimize compliance.)

Is there a structural difference between making massfrac and volfrac? What is the best method for multi-material for minimize mass and maximize stiffness?

 

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Answers

  • Robert Hoglund
    Robert Hoglund
    Altair Employee
    edited June 2023

    Hi Oguz,

    You are looking at a plot for material type.  In the legend, the numbers represent the different material IDs.  In the contour plot, material 2 is red, material 1 is green,  and no material is blue.

    I'm not sure what you mean by reassigning material to empty elements, but you can review the optimization result and organize the elements by material result with the .tcl files that are generated at the end of the optimization.

    Massfrac is the mass fraction, while volumefrac is the fraction of volume for the design domain in the topology optimization.  This can make a difference if you have materials with different densities in the model (as is the case here).

    Multi-material optimization is useful if you have two or more materials with competing properties: for instance a lightweight aluminum; and a stiffer steel and you want to design the optimal structure containing both of the materials.  It can also be useful if you have some known cost function limiting the amount of material usage between one material or the other.

    For stiffness, minimizing compliance with mass fraction is a good starting place: you can also constrain massfrac or volfrac by individual material as well on the DRESP1 card.

    Here is an example model:

    https://help.altair.com/hwsolvers/os/topics/solvers/os/topology_optimization_multi_material_cradle_example_r.htm

    Thanks,

    Rob H.

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