Iterative free-edge stress analysis of composite laminates under extension, bending, twisting and thermal loadings

An iterative method has been applied to analyze free edge interlaminar stresses of composite laminates which are subject to extension, bending, twisting and thermal loads. The stresses, which satisfy the traction-free conditions not only at the free edges but also at the top and bottom surfaces of laminates, are obtained by using the complementary virtual work and the extended Kantorovich method. In order to obtain accurate interlaminar stresses, static and kinematic continuity conditions are applied at the interfaces between plies through iterations. To demonstrate the validity of the proposed method, cross-ply, angle-ply, and quasi-isotropic laminates are considered. Through the iteration processes, the convergence of the solutions is demonstrated. The present method provides accurate stresses in the interior and near the free edges of laminates. It can be utilized as an analytical tool to predict interlaminar stresses under the loads of mechanical and thermal combined. (C) 1999 Elsevier Science Ltd. All rights reserved.