薄膜型声学超材料的结构设计与隔声特性*

为探讨薄膜型声学超材料用于汽车前围声学包、提高其中低频隔声能力的可行性，设计一种米字摆臂多质量块薄膜型声学超材料，构建其隔声分析有限元模型 ，分析其隔声特性及影响因素，开展结构优化及其在汽车前围声学包上的应用探索。研究表明，所设计的薄膜型声学超材料单胞在中低频区域具有较宽的隔声频带；增加薄膜上质量块半径或厚度会使传声损失曲线整体向低频区域移动，且质量块半径的增加还会拓宽高频区域的隔声频带；增加薄膜厚度或预应力会使传声损失曲线整体向高频区域移动；优化后的薄膜型声学超材料与钢板组合应用于汽车前围板，可明显提高其中低频隔声能力。

Structural design and sound insulation characteristics of the membrane-type acoustic metamaterial

In order to explore the feasibility of applying the membrane-type acoustic metamaterials (MAMs) in soundproof treatment of automobile dash panels and thus to improve their acoustic insulation performance at the range of medium and low frequencies, a type of multi-mass MAM was designed. The finite element model of sound insulation analysis was built, the sound insulation characteristics and influencing factors were analyzed, the structural optimization and its application in acoustic treatment of automobile dash panels were investigated. Research results show that the MAM cell that designed in this paper has wide sound insulation frequency band during the middle and low frequency. With increasing of the radius or thickness of the mass block on the membrane the sound transmission loss (STL) curve moves to the low-frequency region. Moreover, the increase in the radius of the mass also widens the sound insulation frequency band at the high frequency region. With increasing of the thickness or pre-stress of the membrane the STL curve moves to the high-frequency region. The application of the optimized MAM combining with the steel plate in the acoustic treatment of automobile dash panels can obviously improve the sound insulation ability at the low and middle frequencies.