A finite element model for the analysis of stiffened laminated plates

Abstract

A refined higher-order displacement model for the study of the behavior of concentrically and eccentrically stiffened laminated plates based on C 0 finite element discretization is presented. The model incorporates non-linear variations of longitudinal displacements through the thickness and hence eliminates the need to use shear correction coefficient(s). Transverse shear deformations are included in the formulation making the model applicable for both moderately thick and thin composite stiffened plates. The plate element used is a nine-noded isoparametric one with seven degrees of freedom at each node. The stiffener element is a three-noded isoparametric beam element with four degrees of freedom at each node. The stiffness of a stiffener is reflected at all nine nodes of the plate element in which it is placed. Accordingly, the stiffeners can be positioned anywhere within the plate element along lines of constant natural coordinates and need not necessarily be placed on nodal lines which gives a great flexibility in the choice of mesh size. The integrals are evaluated by a selectively reduced integration (SRI) technique with three and two Gauss quadrature rules for membrane-flexure and shear parts, respectively. The present formulation is checked for different examples of stiffened plates made of isotropic and fiber-reinforced composites, and results are compared with existing analytical and other finite element solutions.