Research On Ultimate Strength Of Intermittently Welded Stiffened Plates

Ships and marine structures are common large welded structures. The adverse effects of welding will significantly reduce the strength of the structure, and even cause serious accidents. How to accurately evaluate the influence of welding on structure strength is attracting more attention. In recent years, with the widely used of high strength aluminum alloy material in ships and marine structure, the study of the "ultimate strength" become an important aspect of the ships structure strength research. As a new welding form, intermittent welding has already been applied in ship structures. But until now, there are still many problems need to be solved on the effects of intermittent welding on structure strength.In this thesis, the author focuses on related issues of ultimate strength of intermittently welded stiffened plates. Based on current state of ultimate strength research of stiffened plates, this article gives a way to consider the initial imperfection of intermittently welded stiffened plates and does an influential factors research. At last, ultimate strength assessment method research have done by the author. Through this work, the application of intermittent welding is well founded.The main works of this paper are as following:(1) By simulating the temperature and stress fields during welding process, residual stress distribution can be obtained, along with initial disturbance deformation and heat-affected zone, these three factors all make up the initial imperfection of aluminum stiffened plate, which have obvious negative effects on ultimate strength.(2) Analyzing some influential factors such as plate slenderness, weld length and weld number, they all great effect on ultimate strength of aluminum stiffened plate.(3) Through a series of nonlinear finite element analysis, the ultimate strength formulas are obtained and qualitative analysis has been done on the permissible gap of aluminum intermittently welded stiffened plates. The calculation formula of permissible gap which is apply to chain intermittent welding is also given at last.