Limit load carrying capacity for spherical laminated shells under external pressure

Abstract

The aim of the present paper is to discuss possible failure modes encountered in the analysis of multilayered laminated spherical shells having different shallowness parameters and subjected to external pressure. Two various approaches are proposed: the first based on the global buckling analysis and local determination of FPF for each individual layer in a laminate and the second postulating global investigations of both buckling as well as failure (in the sense of LPF) phenomena in laminated structures. The intersection of two curves corresponding to bifurcation buckling and breaking of fibres forms the limit load carrying capacity curve for the analysed shells. The first part of the work is devoted to the analytical prediction of the LLCC curves. Next, the theoretical results are compared with the numerical ones obtained with the use of strict geometrically nonlinear formulation for composite shells. Various types of materials are analysed herein, i.e. both unidirectional as well as woven roving composite materials. The analysis includes also some remarks dealing with the possibility of composite topology optimization in order to obtain the maximal LLCC.