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Ultimate Longitudinal Strength of Hull refers to the overall collapse of the hull to resist the maximum capacity, the ultimate moment of its criteria, it is a ship structural design analysis and calculation of the basic tasks, but also determine the carrying capacity of the hull is an important indicator. This paper analyzes the hull girder stiffened panels under compression may occur in a variety of buckling modes, a simple list of the specification is given in a variety of stress-strain relationship, and as a theoretical basis for this preparation software. Since the longitudinal hull girder ultimate strength of the calculation process, the need to consider the material and geometric non-linear effects, if still use the traditional method to calculate the hull girder ultimate strength, certainly not able to meet the hull simulate the real situation. Therefore, this paper analyzes the gradual destruction method to calculate the hull girder ultimate strength, setting artificially loading to the hull girder cross-section step load to failure, and ultimately get the limit. In this paper, the VB development environment, designed to complete the interface is simple, convenient data input calculation software, which greatly improve the computational efficiency, and also to ensure accuracy. Another very effective method is to use a nonlinear finite element software to calculate the longitudinal hull girder ultimate strength. Nowadays widely used finite element analysis software ANSYS, MARC, MSC / NASTRAN, ABAQUS, ADINA, etc. If we can better simulate the structure of rational truth, nonlinear finite element software is also able to obtain accurate ultimate strength values. In this paper, based on modeling using Prtran with Marc in the arc-length method to calculate Nishihara box girder and a large bulk carriers preferred real ship, and came with the results of this paper close to data compiled software. The paper pointed out that according to the specification ABS SafeHull residual strength of the hull girder damage assessment criteria, calculation models and methods of computation in the original ship complete unit on the basis of the cut to simulate damaged ship, to calculate the remaining ultimate strength. Because damaged hull girder is in a very state of the hull girder will occur at an angle of roll, so the neutral axis translation adjustments not only to consider, but also the need for the angle of rotation. Finally, in order to gradually undermine the development of a practical method of preparing the hull girder ultimate strength and ultimate strength of the remaining damage calculation program, the calculated results with the results of many scholars value and the finite element value comparison, this paper has better software developed accuracy, can be easily applied to the hull girder ultimate strength calculations and checking.
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