Assigning Null or Void Material Properties to Elements in CalculiX

Hello everyone,

I’d like to learn how to assign elements with a null or void material property in CalculiX.
This would be similar to the “Void Materials (LAW0)” feature in OptiStruct, which allows for defining elements to function as empty space or void.
Is there a way to do. if yes!!, could you explain how to achieve this in CalculiX?

Thanks,
Anoop

there’s compression or tension only materials but stress dependent

So you want to perform a topology optimization ? The easiest way would be to define a material with very low (almost zero) mechanical constants and assign it via section to selected elements.

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@Calc_em ,yes!! I am performing Topology optimization. Thank you for your suggestion

is nearly zero value material constants did not make ill-conditioned in CalculiX? i have tried before by factor 1/1000 of neighbor element and shown no problem. However, the support condition is ideally fixed and knot exist at another test.

It could be very small but not too small to avoid such issues.

But there are also ready-made solutions for topology optimization with CalculiX. Like Beso: GitHub - calculix/beso: Python code for topology optimization using CalculiX FEM solver.

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i checked again, CalculiX solver seems to be good enough for jumping of stiffness between neighbor element e.g 1/1000000000 still shown not a problem in my simple case. However, tension or compression only may have more stable and it can be a general solution.

indeed, topology optimization like Beso usually removes the element below criteria and generate final shape to be refined or redraw in CAD.

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