Comparison of analytical and numerical approaches for determining failure of ring-stiffened cylindrical shells

Abstract

The thesis compares the analytical solution, two marine classification society design rules, and numerical analysis against experimental results for predicting the failure modes (general instability, axisymmetric buckling, and asymmetric collapse of the shell) and failure pressures of ring-stiffened cylindrical shells. The analytical solution is first summarized based on several sources. Design rules for the classification societies are then presented with brief explanations for each one. The design rules used are: American Petroleum Institute (Bulletin on Stability Design of Cylindrical Shells, API Bulletin 2U, Second Edition, October 2000) and Det Norske Veritas (Buckling Strength of Shells, Analysis Evaulation and Structural Optimization (MAESTROtm, version 8.5, Proteus Engineering) The United States Navy Naval Sea Systems Command, Submarine Structural Integrity Division supplied experimental data for four test cylinders that covered the failure modes and allowed comparison between experimental and analytical / numerical results. The comparison of experimental to predicted data found the design rules and numerical solution performed adequately in predicting asymmetric buckling and general instability failure modes, but the predictions for failure pressure were unsatisfactory. The design rules were overly conservative in their predictions of failure pressure due to the semi-empirical solutions used in the rules. The numerical solution was only slightly better for the same failure pressure predictions. The results indicate the predicted failure pressure for a cylinder is closely tied to the size and dimensions of the cylinders used for determining the empirical solutions. These results should be further explored to determine causes and corrections.