Opening reinforcement design and buckling of spherical shell subjected to external pressure

This paper focuses on spherical shells with openings and reinforcement under uniform external pressure. To reduce the local weakening and buckling effects of the openings on these spherical pressure shells, the opening reinforcement parameters were optimized to minimize the buckling instability. According to the result of the optimization, two laboratory-scale models were manufactured and tested. The geometry, spherical shell thickness, wall thickness, buckling load, and final collapsed mode were measured for each spherical shell with an opening; the material properties of the corresponding sheets were also measured. The buckling behavior of a simulated spherical shell with an opening was demonstrated numerically according to experimental data. Numerical calculations involved considering the real geometrical shape, average values of parameters, and elastic-plastic modeling of true stress-strain curves. Moreover, the effects of initial geometrical imperfections on the critical load of the simulated spherical shell were analyzed numerically. The scanning model was calculated according to deterministic imperfections obtained from measured geometrical shapes. The theoretical model was calculated according to the equivalent geometrical imperfection valued as the first buckling mode of linear buckling. The results of the experimental and numerical investigations were compared in tables and figures.