Sound Absorption Properties Of Aluminum Foam Application And The Torpedo

Aluminum foam is a new type of multi-functional pore structurematerial, generated through the porous metal matrix composite withporous structure makes it has many excellent properties. As the structuraland functional material light weight, high specific strength, soundabsorption, sound insulation, heat insulation, excellent characteristics ofheat dissipation, electromagnetic shielding, etc, can develop applicationin the muffler, filter, shock absorber, radiator, catalyst carrier anddecorative materials and special properties of composite materials, etc.Thus aluminum foam has received the widespread attention at home andabroad, some of its unique performance remains to be further research,this paper made a further study on the performance of the aluminum foam,as to provide theoretical basis for the wide application of aluminum foam.This paper mainly studied the sound absorption performance ofaluminum foam, seepage casting prepared by different pore structure ofaluminum foam sample and carries on the sound absorption performancetesting and optimization analysis, it is concluded that the best structure ofaluminum foam sound absorption performance of the process parameters,according to the parameters according to the preparation of aluminumfoam sheet, and the aluminum foam plank in the torpedo acoustic noisereduction on the surface of the sea water pump performance test andstudy, and so for the aluminum foam application on submarine torpedoprovides the basis. The results of the study are as follows:(1) Seepage casting was prepared using porous aluminum foam, thekey is the choice of the filler particles and the modelling method.According to the characteristics of the seepage process, filler particlesshould choose to have fireproof, high strength, easy to clean and stablechemical properties of materials. This experiment adopts the NaCl asfiller particles, through the grain of different mixing ratio and differentarrangement of different pore structure of foam aluminium specimen wasprepared. (2) In this paper, a single pore structure was tested by standing wavetube method, mixed pore structure, gradient pore structure and porestructure of aluminum foam sample cycle in250Hz and500Hz and1000Hz,2000Hz and4000Hz and6000Hz and10000Hz frequency of soundabsorption coefficient, found that different pore structure of aluminumfoam in the high frequency sound absorption effect is best, in the highfrequency area, poor in low frequency area.(3) Different pore structure of aluminum foam sample, the aperturesize of0.8~1.1mm, the porosity of65%single pore structure of foamaluminum sample has the best sound absorption performance, followedby a gradient pore structure of aluminum foam sample, again for a hybridstructure and cycle structure of aluminum foam sample, sound absorptionperformance of the worst for the aperture size of3.2~2.2mm, theporosity of65%single pore structure of foam aluminum sample.(4) When the foam aluminium specimen phase at the same time, theporosity and height with gradient structure of aluminum foam sample ofsound absorption performance is better than with mixed structure andcycle structure of aluminum foam sample, and the hybrid structure ofaluminum foam sound absorption performance and cycle structure ofaluminum foam sound absorption performance close to. Aluminum foamsound absorption properties of gradient structure associated with theincident direction of sound waves, sound waves from a large hole into theholes from the sound absorption performance is superior to sound wavescoming from into big hole. Periodic structure of aluminum foam raised onthe sound absorption performance of high frequency area, and reduces thesound absorption performance in low frequency area.(5) To open sound absorption mechanism of porous metal as thebackground, through the contrast and the orthogonal experiment of soundabsorption performance and viscous effect and heat conduction effect ofaluminum foam microstructure analysis found that the sound absorptionperformance of aluminum foam and the size of the aperture size, porosity, pore size distribution of factors, such as there is a direct relationship,various factors, the size of the aperture size of foam aluminum soundabsorption performance of greatest influence, followed by aluminumfoam porosity, again for aluminum foam pore size distribution, but theheight of foam aluminum has a little effects on the sound absorptionperformance of the aluminum foam. If small size of aluminum foamaperture, the internal structure of aluminum foam is complex, with innerholes when sound waves enter the pore wall friction and collisionfrequency increases, thus the more sound energy into heat energydissipation, achieved the purpose of sound absorption.(6) Simulation to study the aperture size of1.1~0.8mm,65%porosity of foam aluminum plate mounted on the torpedo acoustic noisereduction on the surface of the sea water pump performance. Test thesimulation of torpedo sea water pump tooling surface with aluminumfoam and not add sound absorption noise reduction performance ofaluminum foam. The results showed that: after adding aluminum foamthan adding aluminum foam acoustic noise reduction of the average of6dB, with different values under different frequencies of sound absorptionnoise reduction up to15dB, which can show that open groove aluminumfoam for the application of the torpedo acoustic noise reduction of seawater pump is feasible.