The Direct Design and Research of the Double-side Skin Bulk Carriers Converted from a Tanker

According to market demand and design specifications, the conversion of ship uses the old ship, and convert or modify the ship type. And its main advantages are its relatively low investment, short construction cycle and efficiency significantly. The accidents of single-hull tankers became so frequent that the International Maritime Organization had developed a phase-out plan about single-hull tanker. In recent years, it has become common that converse the single-hull tanker to bulk carrier.The basic idea of finite element method discrete structure, and use many finite elements of being analyzed easily to express the complicate object, and apply the finite nodes to interconnect between elements , then make a comprehensive solution according to the conditions of deformation. the direct calculation of hull structural strength use the finite element model, and simulate the actual connection and loading case of the various component respectively by rod, plate, shell and beam element. With the finite element software we can solve the deformation and the stress results of various components. At present, this method is an accurate and perfect method ralatively on hull strength analysis.As the complexity of the hull structure itself and environmental conditions, the direct calculation of hull structural strength is divided into two types: the finite element analysis of module model and the finite element analysis of full-ship model. At present, in the direct calculation of hull structural strength, various country has developed a unique calculation method and strength standard, and widely applied in the practical works. Its applicability is verified by practical works. In the direct calculation of hull structural strength, there is a larger difference about the concrete regulation among the classification societies. But it is roughly the same in main content and calculation process. And include choosing and establishing finite element model, imposing boundary conditions, definiting loading cases, calculating and imposing load, calculating, and analyzing results.In this paper, with the large-scale finite element software MSC.Patran and MSC.Nastran, there will directly design and research the bulk carrier converted from 80 000DWT single-hull tankers. In accordance with the actual design drawings of bulk cargo carrier, this paper establish three-dimensional finite element model of its hull structure, to analyze yield strength and buckling strength by the direct calculation of the finite element,and provide necessary foundation for the designation of this carrier. The cargo loading, wave loading, bending moment of end face are calculated according to Guidelines for Direct Strength Analysis of Double Side Skin Bulk Carriers, 2004 (CCS). While the allowable stress in structure strength evaluation are selected according to Guidelines for Direct Strength Analysis of Double Side Skin Bulk Carriers, 2004 (CCS). And this paper analyzes the buckling strength of the bulk carrier by CCS buckling calculation plug-ins.