泡沫金属及其复合结构吸声性能优化

Optimization of Sound Absorption Performance of Metal Foam and Its Composite Structure

为了改善单层泡沫金属低频的吸声效果并拓宽其吸声频带,本工作将不同结构参数泡沫铝和泡沫镍的单层试样按其吸声峰值所对应频率段进行组合,并交换其前后顺序进行吸声性能研究。利用响应曲面分析法得到吸声性能最优的复合结构的构建参数,并通过实验进行验证。结果表明,将泡沫铝与泡沫镍进行复合并添加背后空腔,组成双层多孔-共振式复合结构。泡沫铝在前的复合结构表现出共振型吸声体的特性,而泡沫镍在前的复合结构表现出多孔材料吸声的特性。复合结构在全频率范围内的吸声效果良好,且单层结构彼此耦合时出现多个吸收峰,其中心频率向低频区移动。泡沫镍在前的复合结构中高频吸声效果优于泡沫铝在前的复合结构。响应曲面分析的结果表明,当泡沫镍厚度取20 mm靠近声源放置、泡沫铝厚度取15 mm靠近刚性壁放置、两者之间添加34 mm的空腔、泡沫铝和刚性壁之间添加28 mm的空腔时,组合具有良好的吸声性能,可以准确获得平均吸声系数达0.920的最优复合结构。实验采用传递函数法测量该构建参数下复合结构的吸声系数,得出测量值为0.916,与响应曲面法得到的预测值基本一致。

In order to improve the low-frequency sound absorption effect of single-layer metal foam and widen its sound absorption frequency band,this work combined the single-layer samples of aluminum foam and nickel foam with different structural parameters according to the frequency bands corresponding to their sound absorption peaks,and exchanged their order before and after for conducting sound absorption performance studies.The construction parameters of the composite structure with the optimal sound absorption performance were obtained by the response surface analysis method,and verified by experiments.The results show that the double-layer porous-resonant composite structure is formed by compounding aluminum foam and nickel foam and adding a back cavity.The composite structure with aluminum foam in front shows the characteristics of resonant sound absorber,while the composite structure with nickel foam in front shows the sound absorption characteristics of porous material.The composite structure has a good sound absorption effect in the whole frequency range,and when the single-layer structures are coupled with each other,multiple absorption peaks appear,and the center frequency moves to the low frequency region.The high-frequency sound absorption effect of the composite structure with nickel foam is better than that of the composite structure with foam aluminum.The results of the response surface analysis show that when the thickness of nickel foam is 20 mm close to the sound source,the thickness of foam aluminum is 15 mm close to the rigid wall,a 34 mm cavity is added between the two,and a 28 mm cavity is added between the foam aluminum and the rigid wall,the combination has good performance.The sound absorption performance can accurately obtain the optimal composite structure with an average sound absorption coefficient of 0.920.In the experiment,the transfer function method was used to measure the sound absorption coefficient of the composite structure under the construction parameters,and the measured value was 0.916,which was basically consistent with the predicted value obtained by the response surface method.