AN EIGHT-NODE HEXAHEDRON ELEMENT WITH REDUCTION OF SHAPE SENSITIVITY AND HIGH PERFORMANCES IN SHELL APPLICATIONS

Abstract

In this paper an eight-node hexahedron finite element is presented. This type of elements are useful for modeling structures with shell and 3D configuration without the need to connect solid elements to shell nodes. The element is based on the displacement mode separation method, which is an unsymmetrical stress-hybrid formulation, with assumed boundary displacements and displacement derived internal stresses. The stress field parameters are grouped on constant stress modes, bending modes and higher order stress modes and are linked to the nodal displacements of the element. The element can reproduce exactly all the six constant strain modes, has correct rank and is of high accuracy in complex applications. The numerical results for known beam, plate and curved shell test problems show an excellent behavior of the proposed element, with a very low shape sensitivity. In some cases, for example beams and plates in constant bending, the elements are even insensitive to distortion.