FINITE ELEMENT ANALYSIS OF SHELLS : DEGENERATED SOLID APPROACH

Abstract

In this work, the three dimensional theory of continuum mechanics has been briefly reviewed. The process of degeneration of a three dimensional solid into more simpler element hads been discussed. Some comments on different theories on plate or shell element are given. Superiority of Mindin-Reissner hypothesis over Kichhoff-Love theory because of relaxed continuity requirment has been discussed. Problems associated with a fully integrated degenerated shell element which use biquadratic Lagrange interpolants has been elaborated. The shear and membrane Irking phenomena with its occurrence and &lamination is described. A general shear deformable 9-node shell element, with 6 degree of freedom at each node, has been implemented. The performance of element has been tested under exact and under integration. The problem of spurious zero energy modes resulting from using reduced integration rule to control the shear and membrane locking problem, is treated by using artificial•stabilization based on projection operator technique. The use of reduced shear integration improves the bending behaviour and this has been checked by means of test problems. The improvement of the element as a shell element however is more due to the reduced membrane integration than to the shear integration. This fact has also been reestablished by the test problems of shells. The importance of proper assessment of hourglass control parameter for deep shell has been se