Membranes for 2D Axisymmetric Models
The Membrane interface for 2D axisymmetric models can be active on interior and exterior boundaries of a solid, as well as on edges that not adjacent to a solid.
The dependent variables are the displacements u and w in the global r and z directions, and the displacement derivative unn in the direction normal to the membrane in the rz-plane. For anisotropic materials, the tangential displacements derivatives u1n and u2n are additionally added as dependent variables.