Ultimate Strength of Pit Corrosion Damnification on Pressure-Resistant Shells of Underwater Glider

The ultimate strength of the pressure-resistant shells is degraded due to corrosion pit on the surface of the shells. The underwater glider is prone to pit corrosion damage after working in the water for a long time. This study is aimed at development of an assessing formula for ultimate strength of pressure-resistant shells with pit damage. Firstly, a parameterized geometry model of the pit is determined under the assumption that the pits are elliptical. Secondly, a finite element numerical simulation model is established and the numerical simulation results are analyzed to find that the effect of pit damage on the pressure-resistant shell is obvious. Thirdly, the influences of some parameters (relative length, relative width, and relative depth) of pit on the ultimate strength are studied. The regular curve of the influence of geometric parameters on ultimate strength is drawn. Lastly, the ultimate strength assessment formula of pressure-resistant shells was obtained from the data by nonlinear FEM based on the regression function of multiple nonlinear regression analysis by nonlinear regression analysis function regress which can provide the foundation to assess the ultimate strength of damaged pressure-resistant shells.