GEOMETRICALLY NON-LINEAR BEHAVIOR OF AN IMPROVED DEGENERATED SHELL ELEMENT

Abstract

The development of an improved degenerated shell element is presented for the analysis of the shell structures undergoing large deflection. In the formulation of the element stiffness, the combined use of three different techniques was made. They are: (1) an enhanced interpolation of transverse shear strains in the natural coordinate system to overcome the shear locking problem; (2) the reduced integration technique in in-plane strains to avoid the membrane locking behavior; and (3) selective addition of the nonconforming displacement modes to improve the element performances. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements and rotations. The resulting nonlinear equilibrium equations are solved by the Newton-Raphson method combined with load or displacement increment. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.