Research On Ultimate Strength Of Stiffened Panels With Pitting Corrosion

The hull is a box structure which consisting of hull plates, longitudinal stiffeners, and beams, and under harsh marine environment, it buckles easily. Because of the marine corrosion, the ultimate strength of hull structure tends to be lower so that it buckles more easily. Many ships tend to be too old, so that corrosion has become one of the main reasons which reduce the life of ships. Therefore, it is very important for residual life assessment of aging ship hull structure to assess its residual ultimate strength after corrosion. Currently, the strength analysis of ship structures considering linear and nonlinear uniform corrosion has been more mature, but influence of pitting corrosion on structural strength still has a lot of problems to be solvedThe purpose of this study is to get ultimate strength reduction factor formulas of pitting stiffened plates and provide a basis for ultimate strength analysis of stiffened panels with pitting corrosion. The main work is as follows:(1) Elaborating the stability theory and FEM computing technique of the stiffened panels. Through selecting the model range, the initial imperfection, the shape of the pits, meshing, boundary conditions and so on, we establish calculation model of stiffened panels with pitting corrosion to calculate its ultimate strength.(2) Analyzing some geometrical and corrosion factors such as finite element type, the shape of the pits, the distribution of the pits, the depth of the pits, initial slenderness ratio, the number of the longitudinal stiffeners, corroded volume loss to find the main influence factor of ultimate strength reduction factor of stiffened panels.(3) Getting a lot of ultimate strength values of T-type and L-type pitting stiffened panels through a large number of nonlinear finite element analysis. The ultimate strength reduction factor formulas of pitting stiffened plates were obtained by analyzing the resulting data.The ultimate strength assessment method of stiffened panels can be applied to engineering practice. On the basis of the corrosion testing data, we can more accurately calculate the ultimate strength of the corroding structure.