Study On The Ultimate Strength And Structure Optimization Of River-to-sea Ships

With the increase of the investment of the Yangtze River in the twelfth five-year plan period, the research on new multi-functional river-to-sea ships becomes extremely urgent, in order to further release potential of the Yangtze River. Because river-to-sea ship designs must give attention to the limits of the draft, we have to increase molded breadth to make up Tonnage loss from the limits of the draft. The ultimate strength problems in rough seas are being received more and more attentions.For a long time, analysis of ultimate strength is based on the classical linear elastic theory. But with the analysis method improved, people are beginning to realize that the influence of buckling, yield and post-buckling of component must be considered. There are four main methods:nonlinear finite element method, direct calculation method ideal, structure element method, gradually failure analysis method.Compared to other calculating methods, the universal finite element program is applied in broader scope and easier to use. Many calculations showed that results of the universal finite element program can be guaranteed if we can take sufficiently into account influence of load and boundary of model, nonlinearity etc...The international popular finite element software includes ANSYS, ABAQUS, SAP, ADINA, MSC/NASTRAN, MSC/MARC, DYTRAN etc..In this paper, ultimate strength of single hull VLCC has been calculated by using the finite-element software MSC/MARC. The modeling method which is suitable for ultimate strength calculation is gained. At the same time, ultimate loading capacity’s variation of BTD series bulk carriers with length is gained. Finally the effective way of increasing ultimate loading capacity of river-to-sea ships has been obtained through changing thickness and material properties of key component of12400t river-to-sea ship. It provides references for the design of river-to-sea ships.