Abstract
Composite materials are well known to have superior specific stiffness and strength to conventional metal materials. Due to the excellent material properties, composites contribute to lighten the structures in various industrial fields. Moreover, it is known that engineers can intentionally change dynamic properties of composites by designing their lay-up configuration. Among the composites, shell structures are often found in the automotive and aerospace industries, but this type of structures has technical problem causing the buckling due to various external loads. Therefore, it is important to investigate buckling response of those structures on the safety design. In this study, the effect of generally shaped pressure on buckling eigenvalues of laminated composite shells is studied and those lay-up configurations are optimized to maximize non-dimensional buckling load or buckling parameters. First, stress distributions of shells under general external pressure are calculated by the Ritz method. Then, eigenvalues as critical buckling loads under in-plane stresses are derived by the Ritz method again where in-plane stress distributions determined in the first step are included as the potential energy. Finally, the layerwise optimization (LO) method is applied to optimize lay-ups and to maximize buckling load of laminated composites shells, and obtained optimum solutions are successfully result in higher buckling load compared with the typical lay-ups.
