For general-use elements, you must define the element's surface area and the direction cosines of the normal to the acoustic fluid-structural interface, pointing into the fluid.

For elements for use in planar models, you must specify the thickness (out-of-plane) of the element. The default is unit thickness if no thickness is specified.

For elements for use in three-dimensional and axisymmetric models, no additional data are required.

*INTERFACE