Residual ultimate strength formulations of submarine pressure hull subjected to collisions of attendant vessels or floating objects

A pressure hull is a primary structural component of a submarine structure that is designed against hydrostatic pressure. When operating in seawater, these structures are constantly serviced by attendant vessels. Thus, collisions between these ships and submarine pressure hulls are unavoidable during its service. For the structural safety requirements, the present regulations and industrial practices have been required to improve the collision strength of these structures under hydrostatic pressure loads. However, the effects of local dents on the collapse strength of submarine pressure hull s remain a challenging problem in ocean engineering structures. Besides, the existing design methods were still limited to predicting these structures’ residual strength after accidental collision loads. It, therefore, needs to provide reasonable approaches for predicting the residual ultimate strength of submarine pressure hull. This study aims to develop numerical simulations and empirical equations to predict the ultimate residual strength of damaged submarine pressure hulls under hydrostatic pressure to solve this problem. The collision scenarios considered in this study could represent the collision accidents between submarine pressure hulls and attendant vessels or floating objects. For this purpose, first, numerical approaches were developed for dynamic collision and collapsed simulations. The accuracy of the developed numerical method was validated by comparing it with the existing test results provided by the authors. Then, the parametric studies were carried out with a series of numerical simulations on the actual submarine pressure hull dimensions with various collision loading scenarios using ABAQUS tools. Finally, the empirical equations were provided through the database of NFEA results. The reliability of derived equations was compared with NFEA results and the available test data. The results showed that derived formulations have pretty good accuracy with the mean value of uncertainty modeling factor (Xm) about 1.26 and a coefficient of variation (COV) around 2.83% compared to available test results. These equations are simple to use for initial design and serviceability limit state submarine pressure hulls subjected to collision accidents with attendant vessels or floating objects in real ocean engineering cases.