Comparison of approaches for determining the failure of stiffened cylindrical shells

Abstract

The thesis compares the analytical solution, two marine classification society design rules, and two design guides against experimental results for predicting the failure modes (general instability, axisymmetric buckling, and asymmetric collapse of the shell LOBAR BUCKLING) and failure pressures of ring-stiffened cylinders The analytical solution is first summarized based on several sources. The design rules for the classification societies and the design guidance from two sources are then presented with brief explanations for each one. The design rules used are: American Bureau of Shipping (Rules for Building and Classing Underwater Vehicles, Systems, and Hyperbaric Facilities, 1990) and Germanischer Lloyd (Rules for Underwater Technology, 1988). The design guides used were Society of Naval Architects and Marine Engineers (Submersible Vehicle Systems Design, 1990) and Massachusetts Institute of Technology Course 13A Professional Summer Notes (MIT 13A Submarine Design Trends, 2001). The United States Navy Naval Sea Systems Command, Submarine Structural Integrity Division supplied experimental data for four cylinders that covered the failure modes and allowed comparison between experiment and design rules/guidance. The comparison of experimental to predicted data found that the design codes and design guides performed adequately in predicting axisymmetric yield and asymmetric buckling. The performance of the design codes and guides in predicting failure by general instability was unsatisfactory. For the experimental failures by general instability, the design codes and guides predicted significantly higher failure pressures than those experimentally determined; resulting in the design codes and guides actually predicting failure by axisymmetric yield in stead of general instability. These inconsistencies in the predictions of failure mode and pressures for general instability should be further explored to determine causes and corrections.