Composite plates with two concentric layups under compression

A new concept for designing composite panels with improved performance under compression is presented. In this concept, the panel consists of two different concentric layups. A Rayleigh–Ritz-based approach to model such rectangular panels under compression is presented. The buckling load and the in-plane stresses everywhere in the plate are determined using an energy minimization approach. The results are compared to detailed finite element models and, for special cases, to other published finite element solutions and are shown to be in good to excellent agreement except for cases where twisting–bending coupling (not accounted for by the present method) is significant. As shown by specific examples, the present method can be used to obtain lighter configurations than single-layup geometries. In addition, the method can be applied to plates with rectangular cutouts and plates with terminated stiffeners.