穿孔机械阻抗板的吸声特性研究

Study on the Acoustic Absorption Properties of Mechanical Impedance Panel With Micro-perforations

为提高低频吸声性能,在机械阻抗板（MIP）上穿少量微孔形成穿孔机械阻抗板（MIPMP）吸声结构。对MIPMP结构吸声性能进行初步研究,建立计算模型,用驻波管测量吸声系数。结果表明,MIPMP结构的吸声为机械阻抗和微穿孔的共同作用。吸声曲线出现两个吸声峰：一个在200~300 Hz,由机械阻抗引起,吸声系数可达0.95;一个出现在300~600Hz,由微穿孔引起。计算模型与实验结果所示趋势一致：随穿孔率的增大,机械阻抗单元吸声峰值先增大后减小,向高频移动,微穿孔单元吸声峰值逐渐减小,带宽增大,向高频移动;随背腔的增厚,机械阻抗单元吸声峰值变大,频率基本不变,微穿孔单元吸声峰值略减小,向低频移动。MIPMP与微穿孔板（MPP）构成的复合吸声结构在200~1 600Hz有好的吸声性能。

The mechanical impedance panel with micro-perforations （MIPMP） absorber is fabricated by piercing micropores on a mechanical impedance panel （M/P） to improve the low-frequency absorption properties. The calculation model of MIPMP is established and several samples are tested by using the standing wave tube. The results show that the absorption mechanism of the MIPMP absorber is a combination of mechanical resonance and cavity resonance. The sound absorption curves appear two peaks which are caused by mechanical impedance from 200 Hz to 300 Hz, in which the absorption coefficient is 0.95 at its highest and micro-perforations form 300 Hz to 600 Hz respectively. The calculation model and the experimental results show the same variation trends： as the perforation rate rises, the peak caused by mechanical impedance increases at first then decreases and moves towards higher frequency, the peak caused by micro-perforations decreases and moves towards higher frequency but the bandwidth becomes wider; as the air-cavity extends, the peak caused by mechanical impedance highly increases but the peak frequency basically has no variation, the peak caused by micro-perforations slightly drops and moves towards lower frequency. The combined absorber composed of MIPMP and micro-perforated panel （MPP） shows good acoustic properties from 200 Hz to 1 600 Hz.