Study On Optimization Of Sound Absorption Performance Of Metal Foam And Its Composite Structure

Noise pollution is becoming more and more serious,and the use of sound-absorbing materials to absorb and reduce noise is the most effective noise control method.The foam metal material has the characteristics of both porosity and metallicity,and has an irreplaceable role compared with traditional sound-absorbing materials.This paper mainly studies the change of the sound absorption coefficient of open-cell and closed-cell aluminum foam and other non-metallic materials and non-metallic materials such as polyester fiber and glass wool with the thickness of the material and the depth of the cavity in different frequency ranges.According to the variation law of its single factor,a combination experiment of structural parameters is carried out;based on the results of the combination experiment,an orthogonal experiment is designed to give the optimal scheme.Finally,the optimal sound absorption model is established and verified by experiments.The combined sound absorption performance of aluminum foam materials with different cell structures was studied,and the sound absorption characteristics of open and closed cell aluminum foams in different frequency bands were combined to explore the law of combined sound absorption.The change of material density,thickness and cavity thickness has a great influence on its sound absorption coefficient.Increasing the material thickness and cavity can make the peak value of the sound absorption coefficient move to the low frequency region,and the cavity has the effect of "similar thickness".The medium-frequency open-cell aluminum foam combination of the same density and different thickness has a significant increase in the sound absorption coefficient in the medium and low frequency range,the average sound absorption coefficient reaches 0.836,the peak value reaches 0.959,the frequency range is wider,and the overall sound absorption performance is excellent.For the combination of open-cell and closed-cell aluminum foam,the peak value of closed-cell aluminum foam is sharper than that of open-cell foam,and the sound absorption effect is better when the noise source is close to the open-cell aluminum foam.The sound absorption of aluminum foam material was extended to other open-cell metal foam materials,and the sound absorption performance of different combinations of open-cell metal foam materials was explored.The sound absorption performance of opencell aluminum foam is relatively good,especially No.1 and No.2 open-cell aluminum foam,which have obvious high absorption peaks and wide half-peak widths.The highfrequency sound absorption performance of copper foam and nickel foam is better.The combination of open-cell aluminum foam and copper foam has the best effect,followed by the combination of copper foam and nickel foam,and the combination of stainless steel foam has the worst effect.The combination of low-frequency open-cell aluminum foam and copper foam improves the sound absorption performance of medium and high frequency,and the overall sound absorption performance of the composite structure is good.The low-frequency No.2 open-cell aluminum foam combination is better than No.1,and the low-frequency sound absorption performance is better.The combination of low-frequency foam metal and high-frequency metal has better sound absorption effect,and the optimal scheme obtained from the orthogonal experiment is basically consistent with the experimental results.The open-cell metal foam with good sound absorption performance is combined with other non-metal porous materials to study the sound absorption law of the combination of metal foam and non-metal materials with different properties,and further analyze and clarify the sound absorption mechanism.Except for foam glass,the sound absorption coefficients of other non-metallic porous materials increase with the increase of sample thickness and cavity depth.Changing the cavity depth changes the position of the sound absorption peak.The sound absorption effect of sound-absorbing cloth 2# is the best,especially in the middle and high frequency region,and its peak sound absorption coefficient is above 0.97.The combined sound absorption performance is better than that of the individual samples,and both the average sound absorption coefficient and the peak value are improved.Among them,the combination of porous ceramics,sound-absorbing cloth 2# and No.1 open-cell aluminum foam has the best sound absorption performance,and its average sound absorption coefficient reaches 0.887.