I noticed some odd behavior with sandwich panel composite laminates in LSDYNA and have traced the behavior to the variable NLOC, which is used to express whether the nodal coordinates depict the midplane of the shell elements or one of the outer surfaces of the elements. If NLOC is 0.0, which is typical, then the nodal coordinates are at the midplane of the elements. But in my case I am modeling a complex wing structure where the nodes are at the outer surface of the structure, thus NLOC = 1.0. <\/p>\n
But if I set NLOC to 1.0, I get odd unanticipated behavior. For my laminated plate shell elements, with a sandwich core, the laminate at the surface takes most of the load and very little of the force is transmitted to the laminate on the other side of the core. I clarified this problem with a simple planar example, a sandwich panel composite in tension, see:<\/p>\n