jsboy,
The ELFORCE (or FORCE) card generates the nodal forces at the four corners of the 2 dimensional element and/or at the center of the element.
If CENTER is specified, only the force at the center is output which is the average of the nodal forces at the corners of the element. ((C1+C2+C3+C4)/4) with C(N) being the nodal forces at the corners)
If CORNER is specified, the nodal forces at the corners as well as at the center is output.
Hope this helps,
Hombre
The CENTER option is the default, by the way.