Hello everyone, i'm new on the forum and I don't have so much experience in Ls-Dyna. I am a master's degree student and i'm am performing impact analysis of aircraft structures in Ls-Dyna for my thesis. I modelled all components of a full-composite fuselage barrel structure as shell as part_composite with ELFORM 2, while the composite material through the material card 54. I bonded components through the contact_tied_surface_to_surface_offset approach and applied an initial velocity to nodes of the structure, in order to simulate a drop test on a rigid surface.
At the beginning of the phenomenon i get several unespected shell elements failure before the structure hits the ground, as in the attached images. Some elements of the stringers fail, and the skin and stringers deform, as if the nodes were approaching each other. This is unespected at the beginning of the phenomenon as the structure is falling without any collision. Have you any suggestions to solve this issue? Are there any mandatory controls cards on contact, element, material, etc that i have to set?
