Abstract
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.
Highlights
Due to the particularity of the underwater glider, the rest of the time will be in seawater except for charging or maintenance
The evaluation of the ultimate strength of the pressure-resistant shell with pit corrosion damage is the basis of the safety assessment for the overall structure
After further calculation and analysis, we found that the pressure-resistant shell with corrosion pits was obviously influenced by the position of the second reinforcing ring near the corrosion pits, which significantly reduced the ultimate strength
Summary
Due to the particularity of the underwater glider, the rest of the time will be in seawater except for charging or maintenance. The pit damage causes the thickness of the pressure-resistant shell to become thinner, which has great safety risks and has serious impact on the safety of the entire underwater glider structure. Yan Zhang et al got the ultimate strength calculation of pitted stiffened plates under uniaxial compression by the data analysis from lots of nonlinear finite element analyses [8]. L Pit center busbar length h Depth of pit t Shell thickness for ultimate strength analysis of stiffened plates with pitting corrosion [9]. The ultimate strength of the pressureresistant shell with pit corrosion damage is calculated by numerical simulation technology. The calculation results are regressed and analyzed by Matlab software, and the empirical formula of the ultimate strength of the pressureresistant shell with pit corrosion damage is obtained
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