Analysis On Sound Insulation Characteristics Of Light Floor Of Urban Rail Train

With the rapid development of economy,both the urbanization and population are increasing, which leading to the urban traffic more and more crowded. In order to alleviate this situation, urban rail transit has came into being, its rapid development will undoubtedly bring great convenience to people’s travel. However, noise pollution accompanied by which has received more and more attention.The noise and vibration of urban rail train not only affect the comfort of passengers, but also lead to the damage of train components, which greatly reduce the life span of the train. These have become the factors that hinder their further development. Under this background, the lightweight design on urban rail train can reduce interior noise on the one hand, and can also save resources on the other hand, and it has become an effective way to reduce the interior noise of urban rail train. So it has important practical significance.This paper made urban rail train floor as the research object and lightweight design the floor as the research target.Moreover,it calculated acoustic performance of floor structures by transfer matrix method, and investigated the various material parameters on the acoustic performance within floor low noise design and provide the basis for selection.The paper firstly introduced the basic knowledge of acoustics and described in detail mass law and coincidence effect,derived the transfer matrix method based on the basic knowledge of acoustics and Biot theory. In order to verify the feasibility of the method, it calculated the sound insulation quantity of the double-layer plates model and compared with the experiment.Then, the paper researched the sound insulation performance of double-layer plates.It analysed the influencing factors of sound insulation of double-layer plates from two aspects: the surface layer material of the inner floor and the porous layer. For the porous layer, the surface density, flow resistance,surface density,elastic modulus and Poisson’s ratio of the mobile phase were mainly investigated. The analysis revealed that different parameters have different influence on the sound insulation performance of the inner floor.In order to further study the effects of the material parameters to sound insulation of the floor, triple-layer plates structures were established based on the doule-layer plates.The study including the arrangement of the plate, the thickness distribution of the porous layer and the change of the thickness of the air layer. What’s more, the sound insulation performance of the double-layer plates were compared with that of triple-layer plates. The results showed that the sound insulation effect of triple-layer plates are better than that of double-layer plates.Changing the order of plates has little influence to sound insulation of the floor,and the smaller thickness difference between two sides of the porous layer is, the overall sound insulation higher.In addition, the change of the thickness of the air layer has little effect on the sound insulation of the inner floor.Finally, the paper focused on the lightweight design of the inner floor. By setting aluminum-steel and aluminum-honeycomb plates,the sound insulation property of the structure of aluminum-aluminum plates which was established in the previous paper was compared.The results showed that when aluminum-aluminum structure compared to aluminum-steel structure, the weight is not as good as the latter,but the sound insulation was significantly improved after the addition of air layer,and the more layers of air layer, the more obvious advantages of sound insulation. The sound insulation quantity is increased by the increasing the layers of aluminum plates. Compared the sound insulation property of aluminum-honeycomb plates structure with that of aluminum-aluminum plates,the sound insulation quantity of the former is higher than the latter in low frequency, so it is suitable for the structure of low frequency section.To sum up, the article investigated the material parameters of the floor and compared the insulation of double-layer plates and triple-layer plates,find out the main factors of sound insulation for the floor,and designed lightweight floor based on that.lt reflects the role of air layer and the layer number of the floor, and provided the basis for low noise and lightweight design and material selection of the floor in the urban rail train.