Force and moment corrections for the warped four-node quadrilateral plane shell element

Abstract

A four-node quadrilateral plate element can be used as a facet shell element only if provision is made to allow for non-coplanarity of the four nodes. The element stiffnesses are generated for a 'mean plane' equidistant from the four nodes, and are corrected by introducing equilibrated forces and moments as the element is 'moved' to the original nodes. In this paper we introduce a rational procedure for determining the 'kick-off forces' and show that the procedure used in NASTRAN violates a virtual work condition and leads to difficulties in certain warped configurations.