Prediction Of Interior Noise Via Air-borne And Structure-borne Sound Transmission And Optimization Of Floor Structure Above The Bogie Areas Of High-speed Trains

The increasing speed of high-speed trains can bring great convenience to people's life;however,it also brings the problem of the interior noise.From the results of the interior noise test and sound source identification,it can be seen that the interior noise above the bogie area is 3-5dBA higher than the other areas,bogie area can be regarded as the most significant noise sources to the interior noise,causing a seriously affects to the comfort of the passengers.Therefore,it is of great significance to study the acoustic vibration characteristics of the floor above the bogie area to the interior noise.In this paper,the interior noise above the bogie area of a typical high-speed train is tested and analyzed,the prediction model based on the hybrid FE-SEA method is used to implement the optimization design of the interior noise above the bogie area.The main research works are listed as follows:(1)The domestic and international research progress and current status of the interior noise of high-speed trains by testing or simulation methods are summarized.The shortcomings of the research on the interior noise of the train above the bogie and the possible research directions need to be solved are clarified.(2)Based on the line test,the interior noise characteristics above the bogie under different conditions were tested.Results show that there exists a significant peak value of the interior noise at the center frequency of 630 Hz.The distribution of the noise source in the vehicle is mastered based on the interior noise source identification test,the contribution of different areas to the interior noise is quantified.It can be found that floor structure is the main noise radiating area to the interior noise.Meanwhile,air-borne and structure-borne sound transmission of bogie area excitation sources to the interior noise are analyzed,results show that the peak of the interior noise has a strong correlation with the pressure excitation of the bogie area.(3)Based on the hybrid Finite Element-Statistical Energy Analysis(FE-SEA)method,the prediction model of the interior noise of the train above the bogie is established.The innovation of the model is that the model considers the multi-layer of the car body,the radiation and transmission characteristics of the floor structures are studied.By establishing response points of the interior cavity section of the train,the sound field distribution is obtained.The interior noise prediction model above the bogie is verified with the line test data.Based on the verified model,the contribution of the air-borne and structural-borne sound transmission are analyzed.Results show that the air-borne sound transmission in the mid-low frequency range in 80-315 Hz is slightly higher than that of structural-borne sound transmission,structural-borne sound transmission plays the main role of the interior noise of the mid-high frequency range in 400-800 Hz.(4)Based on the line test and the interior noise prediction model,it can be found that the floor structure above the bogie is the main contribution area of the interior noise.According to the characteristics of the floor structure,a prediction model of the interior noise above the bogie is established based on the FE-SEA method.The effects of structural and material parameters on the noise and vibration performance of the floor are analyzed,the acoustic optimization design of the floor structure is also carried out.Investigations are made on the noise and vibration performance of the floor above the bogie due to the influence factors such as the materials and structures of the exterior panel of aluminum extruded panel,the interior panel of wood,the connector structures of interior and exterior floor.Results show that the aluminum extruded panel and wood bones are the most effective structures for reducing the radiated sound power of composite floors,the aluminum extruded panel and the interior floor are the most effective structures for improving the sound transmission loss.(5)Based on the optimization results of prediction model and the acoustic vibration performance of the floor above the bogie,the noise reduction effect of the optimized floor structure on the interior noise above the bogie is evaluated via the air-borne and the structureborne sound transmission.Based on these works studied,they can provide a reference and basis for the low noise design of the interior noise above the bogie.