The Sound Absorption Properties Of The Porous Metal

The porous metal is the advancing material in recent ten years. It is structural material with low densitie and high strength ratio and function material having many physical properties, such as shock absorption, damping, sound absorption and so on. Then the application prospects of the porous metal is very good in the high-technology field and the industrial field. Researching the porous metal is the one of frontier topics in the interdiscipline such as material science and the rheology.Based on the sufficient analyses of development about porous and sound absorptive material at home and abroad, this paper announces the validity and feature of porous metal used in sound absorption project. According to acoustic structure theory, acoustic principle of multi-holes absorption material and influencing factors about sound absorption are analysed in the paper. The wave propagation in the porous metal and the BIOT theory are introduced briefly in the paper. In the base of BIOT theory, the model of wave propagation is analysed in the porous metal. The macro perforation plate as the special case of perforated plate,its dissipation potential is injection. However, the sound absorption properties of porous metal is different, its dissipation of the porous metal is nonlinear static resistance. The paper makes the perforated plate as the ideal model, establishes the sound propagation model in the porous metal and analyses the sound absorption characteristic, then analyses the parameters which influence the sound absorption in the porous metal with the Biot-allard model.The parameters which influence the sound absorption of the material are material thickness, porosity, cavity thickness, temperature and so on. The main analysis is the material thickness and porosity which influence the sound absorption in the porous metal badly. Finally the conclusion is that the trend of the sound absorption with the increasing of frequency is "increase-wave crest-fall-trough-increase". The sound absorption is increasing with the increased thickness. But when the thickness gets some number, the sound absorption changes no more. The sound absorption increased with the augment of the porosity and is the best in the porosity as 0.8.