| The ultimate strength of ship hull has been widely paid attention to in international marine field in recent years. After many years research, the traditional elastic design which is considered as relatively conservative, doesn't make full use of the ductibility of metal, and wastes material; People gradually found that the safe factor should be defined as the difference between the ultimate strength of ship and the actual maximal load. Compared to the traditional design method, this method improves the safety and economical return of the ship. Therefore, the ship owners, insurance agents and naval architects have more and more concerns about the ultimate strength of the ship hull.In this paper, the stress-strain relation of the ship steel in non-linear range is approximatively expressed by a four-parameter analytical function. After the coefficients of the analytical function are calculated by a program and the mathematical expression of the stress-strain relation of the ship steel can be achieved. After error analysis, the above method is proved to be practicable.The ship hull can be considered as a thin-walled box girder constituted by stiffened panels. In order to research the ship ultimate strength, the ultimate strength of stiffened panel must be considered. And the web buckling and the stiffener tripping are the two main failure forms of stiffened panel. Based on the two main failure forms in this paper, according to the six failure modes of stiffened panel, the ultimate strength is solved by programming, and the failure mode is presented.Finally, the local buckling strength and the ultimate strength of the 50000 DWT bulk carrier is analysed by SafeHull Phase B software of ABS. The ultimate strength of the ship is solved by the program in this paper, and compared to the result of incremental-iterative method commended by IACS, to prove the practicability of the program in this paper. |
