Researches On Aluminum Honeycomb Sandwich Material For Noise Control In Coaches

Along with the vigorous development of automobile industry, vehicles in China havebeen increased rapidly in recent years, but vehicle noise has become more and moreprominent and been increasingly attended. China is a country based on public transport, ofwhich the amounts on the road is much larger than the world’s average, so the pollution ofcoaches noise can‘t be ignored. In the design, safety and reliability of coaches products,domestic coaches production enterprises have reached international level, however there islittle work being done on reducing the noise so far.Aluminum honeycomb sandwich material is a multifunctional composite material with ahoneycomb structure of aluminum foil and manufactured by high strength adhesive. Becauseof the porous honeycomb structural features, this material shows good performances on soundabsorption, sound insulation and light weight, and becomes an ideal material for coach noisereduction.The thesis focuses on the problem of the coach interior noise. On the basis of theintegrated use of sound absorption, sound damping, sound insulation, an aluminumhoneycomb sandwich material is used to achieve the purpose of controlling the coach interiornoise. This aluminum honeycomb sandwich material is made up of sound-absorbing material,damping material and sound insulation material. First of all, the sound absorbing performanceof this material is studied, through a large number of materials preparation and the absorptioncoefficient determination experiments. The results show that the average absorptioncoefficient of this composite material with an excellent combination of structure reaches0.43,and the absorption coefficient is over0.5from the frequency of1000Hz to4000Hz, whichsupport that this material has good performance on sound absorbing. Then, according to theacoustic theory, the sound insulation performance of this material is analyzed, each layermaterial and structural parameters have been determined. The calculations show that theaverage sound insulation of this material can reach26.8dB (A) in theory. At last, a coachgenerator hood for sound insulation (GHSI) is made of this sandwich material. The Soundinsulation for GHSI and the coach interior noise have been tested.. The Sound insulation forGHSI testing results show that the average sound insulation for GHSI of this material actuallymeasured is19.0dB (A), which increasers4.1dB (A) sound insulation than the original GHSI,sound insulation performance raises27.5%. The interior noise measurement experiment results show that the noise reduction with the GHSI of this material has increased about1.7dB (A) than the original one, that makes a greater contribution to reduce the coach interiornoise. The theoretical and experimental studies have shown that aluminum honeycombsandwich material is a good material for coach noise reduction.