Research On Acoustic Characteristics And Optimization Design Of Layered Composite Material For High-speed Train

In recent years, our country’s high-speed train got rapid development, the construction of the high-speed train has been risen as a national strategy and the development of it has strengthened the comprehensive national strength. Many supporting industries and related basic subjects has got rapid development. With the improving of the design speed of high-speed train, the noise and vibration problem has emerged, it has an effect on the feeling of the comfort of passenger and the service time of the mechanical facility, even sometimes the noise and vibration will endanger the safety of the train. At present, according to some noise test results of high-speed train, the noise level of some certain areas of the interior carriage has affected passengers’ comfort, so we need to take reasonable and effective measurements to control the interior noise. The key point to solve this problem is how to insulate the route of sound transmission. The most effective method is to develop acoustic materials and structures.Supported by the National Science Foundation project-Active control study on multidimensional vibration of precision equipment based on flexible metamorphic mechanism(51275275)、Shandong Young Scientist Research Award Fund-Study on active vibration control of precision equipment based on flexible metamorphic mechanism(BS2010ZZ006) and National863project-Key techniques of vibration and noise reduction in high-speed train(2011AA11A103). The acoustic materials and structures have been optimized and the noise level of the interior carriage has been reduced based on the noise characteristics of high-speed train. At the same time, the weight of the material inside the carriage has also been reduced. Finally we have achieved the goal of green design requirements of lightweight and low energy consumption.Firstly, the numerical simulation model of elastic thin plate is verified by the classical theoretical solution of sound insulation and the experimental test results. It provides technical preparation for the sound insulation forecast of composites. The FEM-Biot-Allard theory is introduced and the equivalent model of porous sound absorbing material is obtained by the experiment test correction.Secondly, the roles of porous sound absorbing materials and air layers have been studied by the transfer matrix theory and the finite element model through proper simplification. The study found that a reasonable distribution of the porous materials and air layer can improve the sound insulation quantity. In addition, plenty of acoustic tests have been done in order to get good sound insulation performance of composite structure. The experiment result can also be useful for further optimization design of the medium parameters of each layer.Thirdly, based on the experiment result, the acoustic optimization design of the thickness of each layer in the composite materials has been done by genetic algorithm. The optimization works mainly focus on some certain specific frequency points and certain band of high noise level. The best thickness distribution of each layer can be achieved by optimize. The final optimization result indicates that the sound insulation property of the composite materials can be increased as well as the weight of the composite materials has been reduced.Fourthly, a large amount of experimental studies on the composite materials based on the material and structure of the real vehicle have been done. Based on the real car aluminum structure and the lining board, the mechanisms of the air layers and the porous materials on composite materials have been discussed. At the same time, preliminary research on the rooves of different quality in composite materials used in the sound insulation has been carried out. In the high-speed train pantograph test bench, the test environment is more close to the real vehicle condition. By a series of contrast tests, it has been verified that the design of composite materials has a good sound insulation performance and has achieved the goal of lightweight, low energy consumption and effective sound insulation.In this paper, the air layer and porous materials in composite materials have been designed for the reduction of the internal sound and vibration of high-speed train under the noise characteristics of the carriage. The composite materials have advantages of lightweight, low energy consumption and high efficiency of sound insulation. It can achieve the goal of "quiet" high-speed train as well as can control the cost of production with significant economic effect and application prospect.