Sometimes, you want to write expressions that are functions of the coordinates in the thickness direction of the shell. If you write expressions based on the usual coordinates, like x, y, and z, such an expression will be evaluated on the reference surface (the meshed boundaries). In addition to this, you can access locations in the through-thickness direction by making explicit or implicit use of the coordinates in the extra dimension.

The extra dimension coordinate has a name like x_llmat1_xdim. The middle part of the coordinate name is derived from the tag of the layered material definition where it is created; in this example a Layered Material Link.