Research On Application Of Noise Reduction Technology Based On Composite Strcture In Cabin Noise Control Of A Hospital Ship

With the development of economy and the increasing attention to human rights in the international community,more and more attention has been paid to the prediction and control of ship cabin noise.Excessive cabin noise will not only affect the comfort of the crew and threaten the life and health of the crew,but also cause fatigue damage to the ship structure and affect the normal operation of the electronic equipment on board.It can be said that the prediction and control of ship cabin noise is a problem that the shipbuilding industry has been committed to solving.In this paper,two kinds of composite noise reduction structures are firstly proposed,one is the multi-layer composite noise reduction structure,the other is the composite noise reduction structure based on the corrugated bulkhead;Then,a hospital ship is taken as the research object to establish the model and predict the cabin noise based on the statistical energy analysis method.At the same time,the influence of the selection of steel loss factor and cavity loss factor on the noise prediction results is studied.Finally,the noise reduction effects of two kinds of composite noise reduction structures on different cabins under different noise excitation are studied.According to the research results,the two kinds of composite noise reduction structures are applied to the appropriate position on the hospital ship.Through the research on the composite noise reduction structure,a multi-layer noise reduction structure of "5mm steel plate + 30 mm damping material + 20 mm cavity + 20 mm light glass wool + 1mm aluminum plate" is finally formed.It is found that the structure can effectively reduce the noise in the frequency range of 500-2000 Hz.For the structural noise excitation source,the structure can effectively reduce the noise of the source cabin,but has little effect on the cabin outside the source cabin;for the air noise excitation source,the structure can effectively reduce the noise of the cabin outside the source cabin,but has no effect on the cabin itself.Adding 1mm aluminum plates on both sides of the corrugated l bulkhead to form the cavity structure and laying damping materials on the bulkhead can significantly improve the sound insulation,and filling glass wool in the middle cavity structure can effectively reduce the noise within the frequency range of 500-2000 Hz.The noise reduction effect of different cabins under the action of different noise excitation sources is consistent with the characteristics of the noise reduction effect of the multi-layer composite structure.Through the research on the selection of loss factors of steel structure,it is found that when the cabin is dominated by medium and low frequency noise,the result of noise prediction by using the loss factor calculated by empirical formula is quite different from that by using the loss factors recommended by China Classification Society,and the farther away from the source cabin,the greater the difference between the results of noise prediction using two kinds of loss factor of steel structure.Through the research on the selection of cavity loss factor,it is found that the results of noise prediction by using the loss factors calculated by empirical formula are more conservative than that by using the cavity absorption coefficient recommended by China Classification Society.1% absorption coefficient can replace the loss factor calculated by empirical formula,and it is more simple and convenient.