Stability of Orthotropic Stiffened Composite Plates

Energy method, together with Lagrangian multipliers, is used to solve the stability problems of orthotropic stiffened and unstiffened plates under various boundary conditions. Stretching modes in addition to the flexural mode are taken into consideration owing to the existence of the coupling terms in the orthotropic elastic relations. The effective widths and plastic deformations of the isotropic parts are incorporated into the stability configuration. The theoretical results compares favorably with those from tests and literature. Conventional concepts about isotropic materials are not always applicable to the more sophisticated orthotropic structure. Deep understanding to the behavior of the composites is a basic requirement for a sound utilization of the material.