Ship Form Optimization Method Research For Minimum Resistance

The goal of designing an optimal ship form with minimum resistance is a research emphasis for ship designers when main dimensions, displacement and ship speed are offered. Ship model test is used to choose a good ship form with a good resistance performance from a series of ship forms. A lot of labour, financial and time resources will be wasted if this method is used. In this paper, Ship form design method for minimum resistance is discussed by theoretic calculation.Presently, A lot of ship form optimization is researched based on wave resistance. SUMT programming, quadratic programming and etc of nonlinear programming are often used to solve the optimal problem, These optimal methods proved serviceability. In the paper, Sequence linear programming is used to solve ship form model to obtain an optimal ship form with minimum resistance based on LINGO software. Object function is the total resistance which consists of wave resistance and frictional resistance, The wave resistance is expressed by Michell integral formula, Frictional resistance is expressed by the equivalent plank frictional resistance; The design variables is expressed by two formats: hull offsets taken as design variables and parameter of hull modification function taken as design variables; Two basic constraints of necessary volume and hull offsets more than or equal to zero.First, Hull offsets taken as design variables, Optimal model is constructed to optimize the fore and whole part of hulls of Wigley and S-60. The optimiation result is compared with the result of SUMT programming to show that this method of sequence linear programming is feasible. Secondly, Parameters of hull modification function taken as design varibles, Optimal model is constructed to optimize the fore part of hulls of Wigley and S-60. The optimization result is compared with hull offsets optimization result to show that the resistance reduction of the two methods is close. The method of taking less parameters of hull modification function as design variables to optimize ship hull is feasible. Sequence linear programming is realized by Lingo software. The optimization result shows that the LINGO software taken as a optimization tool to optimize ship forms is feasible. It will save a lot of time and provide a researching method for the future ship form optimization research.