The buckling and layer failure characteristics of composite laminated cylinders subjected to hydrostatic pressure were investigated through finite element analysis for underwater vehicle application. The Tsai-Wu failure criteria were used as the failure criteria for the buckling analysis. A sensitivity analysis was conducted to research the influence of the number of elements on the critical buckling pressure. ANSYS, a finite element program, successfully predicted the buckling pressure with 5.3–27.8% (linear) and 0.3–22.5% (nonlinear) deviation from experimental results. The analysis results showed that the cylinders can carry more pressure after a slight decrease in pressure and recovery of the supporting load. For layer failure analysis, it was found that the failure that occurred in the 0° layer was more serious than that in the 90° layer within the neighboring layers at the inner layers (nos. 1–7) and outer layers (nos. 8–24).

Abstract.Composite is used to substitute aluminum alloy as material of the underwater vehicle in this study. Nonlinear buckling behaviors of composite cylindrical underwater shell are studied using ANSYS software. Carbon/Epoxy is selected as material of the vehicle through comparative analysis. Optimization of ply sequence, thickness and angle of composite cylindrical shell subjected to hydrostatic pressure is investigated. Both buckling and material damage is considered in the optimization, the results show that buckling is the major destroy form. The vehicle's buckling pressure is greatly increased after optimization. And the vehicle's working depth has a 32% increase without changing its shape and structure.