The Efficient Absorption Structure Optimization Design Based On The Sound And Vibration Characteristics Of High Speed Train

Along with the rapid development of economy, high speed railway transport hasbecome the Chinese railway development of important strategic objectives. Railwayproduced enormous high economic and social benefit, and also brought manyenvironmental problems, including the influence of the external and internal cabinenvironment noise. It is very outstanding.The sound environment internal high-speed train cabin is one of the importantfactors which decide the passenger comfort. Along with the ascension of the trainspeed, the interior noise problem causes the more and more attention of people. So it isnecessary to study and analyze the interior noise source characteristics and the acousticfield distribution characteristics of high-speed train cabin. And then do some effectivecontrol for the interior noise.Micro-perforated panel absorption structure was put forward by Mr. MAADah-You. It has been widely used in recent years. And it becomes one of the effectiveways for noise control which can be optimization designed according to thecharacteristics of interior noise. It will achieve good sound absorption effect.This paper first introduced the main sound sources and its mechanism ofhigh-speed train noise. Through multiple operating condition of different models ofreal vehicle testing experiment, we analysis the characteristics of main noise sourceinside the cabin and the contribution in total noise. Clear the noise distributioncharacteristics interior high-speed train.Paper involves three kinds high speed car, A B and C. We did three tests for them.Through the test result analysis, we found that: the vibration and pressure level of thevehicles increase with the train speed increased, but different regional value-added arenot identical. The vibration of the bow roof area is different from other local floor and wall. The internal and external vibration level of this area is similar, all in higheramplitude. At other positions (central car roof, floor, wall, etc), the vibration is similarinside and outside the car in the low frequency. But the vibration significantly reduceand to be agreement at high frequency. The increase of vibration outside the car isobvious with the frequency increased, far higher than the inside car. Through thecomparison of the vibration in the three kinds of models, found that: under the samespeed per hour (350km/h), the inside roof floor and wall vibration of type B car aresignificantly lower than type A car and C car. The sound pressure level at the front ofthe car is more than the central pressure level.On the other hand, in order to find the effective absorption structure whichsuitable for high speed train structure characteristics and the characteristics of soundfield, based on the basic principle of noise reduction of the micro-perforated panelacoustic absorption structure, this paper discusses the absorption characteristics ofmicro-perforated panel sound absorption structure. For high-speed train interior noisespectrum characteristics, puts forward new micro-perforated panel absorption structure—Arc-Tapered MPP, and the absorption characteristics of the new structure aregiven, and the design parameters adapted to the high speed train interior noisespectrum characteristics are given.Through the MATLAB simulation analysis, get the following conclusions:(1)When the angle is little smaller than90, sound absorption effect is better at the lowfrequency, but with a narrow suction audio; If the noise focus on high frequency, it isbetter choose of a little bigger than90.(2) With the aperture declining, the peak ofabsorption is increasing, but its resonant frequency points also to move to highfrequency, and the influence of the bandwidth is not obvious.(3) When the angle islittle smaller than90, the absorption resonant frequency move to the high frequencywith the increase of perforation rate, and the absorption peak evidently decreased, andabsorption bandwidth do not change significantly. This time the perforation rate shouldnot be too big. When the angle is little bigger than90, the absorption resonant frequency move to the high frequency with the increase of perforation rate, absorptionbandwidth do not change significantly, but the absorption peak evidently increased.(4)The resonance frequency move to the low frequency with the increase of the cavitydepth, the effect to the peak and bandwidth of sound absorption is not obvious.