Buckling and post-buckling response of curved, composite, stiffened panels under combined loads including pressurization

In recent years, metal stiffened shells for aerospace applications have been gradually replaced by composite shells, which are widely used in fuselage, tail, and wing structures due to their advantageous properties. Under operating conditions, stiffened panels are subjected to different types of loads, combined in various ways, which can lead to instability. Like their metallic counterparts, allowing post-buckling within the operational envelope could lead to significant weight reductions for composite structures, but unlike the metal case, their response in this state is not fully understood and the potential of composites is not fully exploited. In this context, the main objective of the present work is to investigate the buckling and post-buckling behavior of composite curved panels subjected to combined loads. The buckling behavior of a representative stiffened curved panel has been simulated by non-linear finite element analyses, from the simplest pure compression and pure shear cases to the final analysis of the panel subjected to pressurization, shear, and compression simultaneously. The results of this study quantify the reduction of the critical compression and shear loads due to their simultaneous action, as well as the effect of the pressurization load, which was generally beneficial, but remarkably so in the case of pure shear.