Research On Vibration And Noise Transmission And Control For Steel-Aluminum Mixed Structure High-speed Ship

Vibration and noise problems of ship have always been attracting attention of people, especially for high-speed ship, the requirements of the level of which are higher than common cargo ship.The ship vibration and noise problems will not only affect the operation of instruments and equipment, but also affect the comfort of passengers and crew as well as hurt their health, what's more, may endanger the safety of the ship structure.In facts, if the noise control treatments are applied after ship has been built, in most cases the problem can only be solved partially, and also shipbuilding costs maybe increase greatly. If the research and prediction on characteristic of shipboard vibration and noise carried out in the early stages of ship design, together with corresponding acoustic design projects are proposed, which is of important value to improve the acoustic performence, meanwhile, it can shorten the shipbuilding cycle and reduce costs.Large number of high-speed ship adopt steel-aluminum mixed structure to reduce weight and improve speed of shipboard an so on,in another word,the material of main hulls is steel and that of superstructure is aluminum. The steel-aluminum mixed structure is different from general ship structure, the acoustic property takes on itself characteristic. The paper research object is based on it, the research contents are as follows.The sound insulation of stiffened-aluminium and stiffened-steel plates are investigated.Sound transmission function of stiffened plate is deducted by Statistical Energy Analysis method and sound transmission lost of stiffened aluminium plate and stiffened steel plate is investigated by SEA module of VAOne software and a genenral simulation model for calculating sound insulation of stiffened plate is established. The validity of simulation model of stiffened plate which is adopted to investigate sound insulation by comparing simulation results with former experiments datas. The influence of related parameters on sound transmission lost of stiffened plate also is studied based on the front principle.The research provide references for the design of sound insulation about stiffened plates, especially bulkhead of aluminium superstructure and insulation apron of bulkhead.Transmission law of elastic waves through line form and L form steel-aluminium junction by using Wave guide theory, and numerical value estimation of transfer parameters is carried on synchronously by using matlab software.The calculation results are accord with correlative scientific law and research conclusion of former researcher.The research conclusion is that Transmission law of elastic waves through line form and L form steel-aluminium junction is different from Homogenous plate juctions. Some measures and advice of augmenting transmission loss of vibration elastic waves are proposed.As for vibration control aspect, optimization of the inactive vibration control by damping treatments With Modal Analysis Method and Finite Element Method.Paper compared the effect of absorption of continuous laying damping and discontinuous laying damping, and also analyzed the effect of laying location and laying thickness of damping and other parameters on vibration response.Then optimization method of vibration control by damping treatments is proposed, location and thickness of damping are gained corresponded to the optimization goal in succession. As for noise control aspect, first the impact of the application of unconstrained and constrained damping lay along the waves transimission paths on shipboard cabin noise pressure level.Then The impact of thickness on sound absorption of three kind of hackneyed composite absorption material is studied,and cabin noise pressure level of shipboard after of the application of multilayer-composite structure is predicted,several kinds of optimization structure combination form are put forward and the sound insulation frequency traits of multilayer-composite structure are also analysised. All of these control measure has a certain reference value for the acoustic design of the ship structure.