E4 AND MITC4+ SHELL FINITE ELEMENT PERFORMANCE ANALYSIS

Abstract

This paper presents a correction of the 4-node MITC (Mixed Interpolation of Tensorial Components) quadrilateral shell finite element, i.e., MITC4 element [1]. Correction refers to the improvement of membrane behavior, where the components of membrane strain in mid-surface of the shell are assumed using the concept of MITC method. In other words, the mid-surface of 4-node quadrilateral shell finite element is subdivided into four triangular domains, in order to construct the assumed membrane strain field by using the membrane strains obtained from those four triangular subdomains of the shell finite element [2]. The purpose is to reduce membrane locking that happen when the MITC4 shell elements are geometrically distorted in curved geometries, while the element retains good membrane behavior. Numerical results obtained with E4 shell finite element [3], which is implemented in software package PAK, are presented at the end of the paper and compared with those obtained with MITC4+ element. This numerical example shows the main problems of E4 element in the case of very thin shells and curved geometries, which should be significantly reduced by using the abovementioned modified element.