GENERALIZED CONFORMING QUADRILATERAL MEMBRANE ELEMENT WITH VERTEX RIGID ROTATIONAL FREEDOM

By introducing vertex rigid rotation as a freedom, two new quadrilateral membrane elements with a simple form of formulation are derived from the concept of the generalized conforming finite element [Long and Xin, Finite Elements Anal. Design 5, 15-30 (1989)]. The elements pass the patch test for any geometry, therefore assuring convergence to an exact solution with consistent mesh refinement. The numerical results from selected test problems show that very good accuracy is achieved for both displacement and stress, even for a distorted finite element mesh.