Hybrid quadrilateral element based on mindlin/reissner plate theory

Abstract

Two quadrilateral hybrid Mindlin plate elements QPL4 and QPL6 based on a new functional [1] are proposed here. In this formulation the displacements are decomposed into two parts, and the internal displacements are able to impose two different types of constraints on the shear strains of the element. For the first type, locking is eliminated indirectly through increasing the constraints on the shear forces and bending moments, while for the second type the constraints are imposed on the shear strains directly, and corresponds to the technique employed for the displacement type models. It will be shown that the element QPL6, which belongs to the first type, is a superior element and can achieve high accuracy and convergence without oscillation over a wide range of plate thickness/span ratios. By adopting the natural coordinate interpolation system, the elements are coordinate invariant. Furthermore, the separation of stress field variables enables the element to yield more accurate stresses. A number of examples is used to demonstrate the accuracy and reliability of the proposed elements. © 1989.