FEBio Export from AEVACMB defines surfaces as shells
Using AEVACMB 22.08 on the 9/12 nightly release:
When exporting a simple two component model, surfaces of the model are reported as elements, which is the incorrect definition for FEBio, as they then become zero thickness shell elements. The solution perhaps could be to ensure that anything exported to FEBio with a volume has the surface defined as a surface, as only "copy of Skin_All_Faces" is found in the surface panel. From the FEBio manual (https://help.febio.org/FebioUser/FEBio_um_3-4-Subsection-3.6.5.html):
"Surface elements cannot overlap element boundaries. That is, the surface element must belong to a specific element. Surface elements do not contribute to the total number of elements in the mesh. They are also not to be confused with shell elements."
See the below image for overview of febio file generated:
Here is the smtk file, and associated underlying files that produce this issue: Flat_Tissue.7z