Reliability Analysis of Submarine Pressure Hulls With Failure Governed by Inelastic Buckling

Due to the complexity involved in the inelastic buckling collapse mechanism of stiffened shell structures, the reliability analysis of submarine pressure hull, in which failure is dictated by inelastic effects, assumes great significance among structural engineers. In spite of many years of efforts by different authors to develop good prediction techniques for plastic and elastic-plastic buckling of stiffened shells and also to use the reliability concepts in the submarine pressure hull structures, comprehensive and reliable methods are still scarce. Hence in this paper a rigorous Finite Element analysis of a typical internally ring stiffened submarine pressure hull with failure governed by inelastic overall buckling has been done using the general purpose finite element software NISA. The samples required for each random variable were generated using Random Polar Sampling Technique (RPST) in which the combinations of variates are obtained using a random polar sampling of Latin hypercube sampled values. For the obtained collapse pressures, the reliability of the pressure hull structure has been determined and the effect of mean service loads on reliability has been analysed by taking different Central Safety Factors. The results were validated using Johnson-Ostenfeld Inelastic Correction method and the conclusions are advanced.