Study On Vibration Characters Of Catamaran

In recent years,the SWATH catamaran has developed rapidly for its advantages in seakeeping performance,wide decks and excellent maneuverability.The vibration characteristics of SWATH is more complicated than the monohull ship because of its special structure.At present,the forecast method of catamaran’s vibration characteristics is mainly based on the three-dimensional finite element model,which requires much work on modeling and can’t be used in the early design.Therefore,it is very necessary to study the vibration characteristics and the simplified calculation methods of vibration analysis for SWATH catamaran.The main contents and conclusions are as follows:(1)Vibration characteristics analysis of the whole ship.The threedimensional finite element model of one SWATH was established.Modal analysis based on the finite element method and dynamics theory was conducted,so the particular vibration characteristics of catamaran compared with monohull was summarized.In addition,the effects of the added mass to vibration characteristics was discussed.(2)Study on simplified calculation method.The simplified models of one dimensional single-beam and space beam series model were established.Their applicability to the catamaran was studied on the natural frequency and vibration mode.The existing empirical formula of the natural frequency was amended and applied to the SWATH in the paper.(3)The effects of the design parameters.The design dimension such as cross deck and strut length,and design stiffness such as moment of inertia were took as the study parameters.Their influences on vibration characteristics of catamaran were studied.(4)Vibration characteristics of the local structure.Three key issues including the integration of the mixed model,scope of the local model and boundary conditions while establishing the vibration analysis model,were studied for the tail,the dive body and the partial plate structure.