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compression modelling of lattice: over closure

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May826

Materials
May 22, 2019
1
Hi All,
I am modelling a compression test (quasi-static) for a micro lattice structure till 60% of strain.
i run through implicit and also explicit but the problem is that I saw overclosure or penetration of top platen into the top surface of lattice at later time step (around 60% of strain). I tied top and bottom platen to lattices and also used self-contact for individual struts.
I also did hard contact for top and bottom for another simulation but I saw the same overclosure.
Moreover, I know that when I tied the top and bottom platen to the lattices , the initial stiffness is way higher than what I got from experimental test.
I am just wondering if BC and contact is correct.
Can anyone give me advice how I can sort out the problems (over-closure and high initial stiffness).
Many thanks for your help on this point.
I have attached a .inp file.

Untitled_yayomm.jpg
 
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Here are some tips:
- refine the mesh of the lattice
- use general contact instead of self-contact
- tie only one plate (contact will work for the other one)
- use Explicit solver
 
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