Modal Interaction Studies in Cylindrical Shell Buckling through Advanced Multimode Analysis Tools

Two advanced multimode procedures for the nonlinear buckling analysis of circular cylindrical shells are presented. The first approach corresponds to a semi-analytical method which can accurately take into account the effect of the boundary conditions at the shell edges. The second procedure is based on a perturbation approach and can be seen as a nonlinear reduced order model integrated in a Finite Element framework. The two approaches are described and modal interaction studies are presented for cylindrical shell buckling under axial compression. Results for a specific composite shell are shown, illustrating typical modal interactions and the corresponding decrease in shell buckling load for selected imperfection shapes. The understanding of the effect of modal interactions attained through dedicated tools such as the multimode procedures presented in this work can complement the information obtained from full model Finite Element analysis.