Effects of Secondary Structure on the Stress and Stability of Submarine Pressure Hulls

摘要

This report presents an investigation into the localized effects of secondary structure such as decks, tanks and cutouts, and other deviations from axisymmetry on thee global failure load estimation of axisymmetric submarine pressure hulls. Three dimensional finite element analysis predictions of stress, elastic bifurcation buckling, and nonlinear collapse loads of a representative complete section of a conventional submarine are compared to those of axisymmetric analysis methods applied to the pressure hull alone. Four different methods of analyzing the basic axisymmetric pressure hull are also compared. Stress patterns, buckling mode shapes and failure loads of the fully developed structural models were found to differ significantly from those obtained assuming complete axisymmetry. The inclusion of decks and tanks increased the fialure loads, whereas cutouts and dents in he pressure hull lowered the failure loads. In addition to analytical results experimental strain measurements made on an Oberon class pressure hull are compared to finite element predictions.