The Numerical Calculation Of Trimaran's Seakeeping And Wave Loads Affected By Hull Form Factors

With the development of Chinese economy, more and more new types of ship and ocean structure are developed. The new design method is required for achieving safe ships and ocean structures. With the wide use of the three-dimensional finite element method, the calculation of wave loads on floating body in the waves is in need more and more. It sets forth new requirements for the prediction of ship motions and wave loads.Presently, optimization is used by the designer as an important kind of measure for improving performance in the process of design. One more intuitionistic method for changing the performance is to control the hull form essentials which affect the performance. As it is familiar to us, the parameters that affect ship resistance are: length, beam, draft, prismatic coefficient, longitudinal center of buoyancy, midship coefficient and etc. As a new type of vessel, the highspeed trimaran designers must have a knowledge of the hull form parameters which affect the trimaran motions and wave loads to seek the hull form for better seakeeping performance. Thus it's available for selecting suitable parameters in the design process and getting improvements on the existed parameters in the process of performance optimization. Anciently, the designer expressed the primary and secondary extent of influence of hull form essentials affecting the performance through tank experiment. It will use a mass of manpower and material resources in this way. Recently, it provides a convenient approach for the ship design along with the development of computer and all kinds of commercial software springing up. The designer may work out ship performance conveniently in virtue of commercial software which has sufficient precision.However, just only one ship calculation has no practical significance, it's essential for a systematic calculation. In view of this point, series hull form variational program is needed. Change one parameter and keep the other parameters constant by adjust another variable. The program has four subroutines: STRETCH module, CMVRAY module, CHANGECP module, CDRAFT module, providing four varying patterns respectively: length, beam, draft scale transformation, section form transformation, prismatic coefficient transformation and displacement transformation.According to the series of hull form derived from the program, it carried out a detailed calculation in freedom movement of six degrees and the ship wave load taking into account the effects of side layout in this paper. First of all, I analyzed the influence of seakeeping performance affected by hull form coefficient, and sum up the results of the test in resistance and seakeeping at home and abroad. On the basis of conclusions above, the calculation of motions and wave loads of single vessel in different sea direction and speed and different hull form and side part layout in constant sea direction and speed is done partly. It analyzed the characteristics of motions and wave loads of trimaran and the impact of motions and wave loads affected by the hull form and side part layout on the basis of the result.