Unloading, Mullins Effect on HYPERFOAM

I am newbie to Finite Element Method analysis and CalculiX.
I would like to perform dynamic nonlinear contact analysis including the “unloading” part of foamed resin material (HYPERFOAM) with Mullins Effect. How should I do it with CalculiX?
There is the keyword “* MULLINS EFFECT” in Abaqus, but I can’t find it in CalculiX.

I think the loading and unloading parts need to be in separate steps, but is there any way to do it in one step?
If the steps are separated, is it necessary to separate the material definitions and switch the material definitions?

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Hi @suzuki_h, I believe that the Mullins effect is not implemented yet in CalculiX.

Definitely, the keyword is not in the current ccx manual.
So, the option here would be to implement your own user material subroutine (UMAT), where you specify the parameters for the foam material + the damage due to Mullin’s effect.- A good starting point would be the same format as in Abaqus in terms of coefficients and data needed.

I’ve done it both ways and the results are the same, but I find it more convenient to break it down into two steps.

I don’t think so, but I’m not sure if you can change material definitions within two steps in ccx- I would have to look into that.

Hopefully you can implement the UMAT and contribute to the main code.
Good luck with this!

Thank you for your prompt reply.
After all, you say that I have no choice but to use UMAT or Mfront.
But they are high hurdles for beginners.
I will consider options including the use of another non-commercial solver such as Code_Aster.
(However, it seems that Code_Aster did not have HYPERFOAM…)

I am using ccx_paradiso_dynamic.exe and PrePoMax.