Element Out-of-Plane Stiffness Matrix

Out-of-plane bending accounts for Dz, Dox and Doy of the local coordinate system.  By default, the MITC4 thick plate formulation is used [Ref. 1].  If the thin plate option is chosen, elements with rectangular shapes will be calculated based on the Kirchhoff thin plate formulation [Ref. 1].  Full two by two numerical integration is used in either case to calculate the out-of-plane stiffness matrix of the element.