Hello fellow students, researchers, technical staff, etc...

I am currently pursuing my master thesis at the University of Twente. In this project I am working with the software package nTopology for its capabilities with regard to lattice structures. Therefore, I am also utilising the FEA tool within nTopology to simulate the compressive deformation of lattice structures.

The problem related to my question is that I define lattice structure as shown in the image (see attached file): a top plate, a bottom plate, and in between an arbitrary lattice infill. In reviewing the FEA results I see considerable deformation in the top plate rather then in the lattice structure itself. Intuitively, I believe this is wrong. Therefore, I would like to introduce the plates as being rigid bodies such that the entire deformation occurs within the lattice structure, which is the component of interest.

I have not found a solid solution to this problem yet. The only alternative solution I figured was applying a much higher stiffness to the plates to let them approach rigid bodies. This seems to work but requires a much higher input force to achieve marginal deformation.

Anyone that has encountered a similar issue and managed to find a more fitting solution?