Study On Ultimate Strength Calculating Method For Ship Hull In Its Entire Life

Ultimate strength of ship hull structure is the largest ability to resist the collapse of the whole ship structure. Calculation of the ultimate strength of ship hull structure in its life cycle is benefit for evaluating the actual safety margin of ship structure in its service time, using material rationally, reducing the ship weight, lowering manufacturing and maintenance costs and increasing load capacity.The method of calculating the ship hull ultimate strength is considering the variety of strength in design, construction, and operation in order to provide technical support rationally. The structure ultimate strength mentioned above is ultimate strength of the ship hull structure without defect. During the operating period, damages caused by corrosion and fatigue reduce the ultimate strength of hull structure variety gradually. Obviously, ship hull structure ultimate strength is a time dependent issue considering the structural fracture and corrosion. It is necessary to study the ship hull ultimate strength with damage.In this paper, calculating ship hull ultimate strength in its life cycle is based on the Smith method and considering the effect of time-varying factors such as corrosion damage, fatigue crack damage. In order to propose a method of calculating the ultimate strength of the plate with arbitrary located crack and the ultimate strength of the stiffened panel with complex crack, non-dimensional parametric analysis is conducted. In the end, a method of calculating ship hull ultimate strength in its life cycle is proposed and the corresponding program is developed.The results demonstrate that Smith method can describe the collapse of the hull structure model correctly. The effect of corrosion damage and fatigue crack damage factors on the ultimate strength can be quantified with Smith method. The method of calculating ship hull ultimate strength in its life cycle is validated with test data and FEM results. The results show the present method has good applicability and application prospects.