打孔提高闭孔泡沫铝吸声性能的机理分析

采用驻波管吸声系数测试仪分别测定闭孔泡沫铝板、打孔闭孔泡沫铝板、打孔铝板的吸声系数,结合共振结构吸声特性曲线,分析闭孔泡沫铝打孔后的结构特征,对吸声机理进行探讨。结果表明,打孔后闭孔泡沫铝吸声系数峰值可达0.68,高于未打孔时的0.42,也高于打孔铝板的0.45,降噪系数同样有所升高。打孔闭孔泡沫铝吸声机理主要是由于表面漫反射的干涉消声、内部微孔和裂纹造成声波的能量耗散、打孔后与背板间形成共振结构及打孔对内部孔洞的结构改变增大了吸声。

Mechanism Analysis of Sound Absorption in Perforated Closed-Cell Aluminum Foam

Sound absorption coefficients of closed-cell aluminum foam board, perforated closed-cell aluminum foam board, and perforated ordinary aluminum board were measured respectively by Standing Wave Tube Tester to investigate structure characteristics of perforated closed-cell aluminum foam board and mechanism of sound absorption based on characteristic curve of resonance structure sound absorption. The results show that sound absorption coefficient peak value of perforated closed-cell aluminum foam is 0.68, which is higher than that of unperforated closed-cell aluminum foam board of 0.42 and perforated ordinary aluminum board of 0.45. Noise reduction coefficient also rises. Mechanism of sound absorption of perforated closed-cell aluminum foam includes noise elimination by interference of surface diffuse reflection, energy dissipation of acoustic waves caused by internal micro holes and cracks, resonance structure formed between hole and back board, and structure change of inner hole.