膨胀腔类超材料的传递损失研究*

声学超材料及结构已被广泛研究，其超结构通常利用3D打印技术实现，当结构刚度较小或者面积较大时，由声固耦合所导致的声学效果与设计不符的情况广泛存在。本文针对含有膨胀腔类的超材料，研究了声固耦合对其声学性能的影响，采用有限元计算结合阻抗管实验的方法，得到其传递损失，分析了声固耦合现象对传递损失的影响。结果表明：薄壁膨胀腔结构的作用频率范围与只考虑声学理论计算的设计不符，声固耦合现象对传递损失产生显著影响；采用增加膨胀腔壁厚、减少膨胀腔内径或选择金属材料的方式，都可以使得声固耦合现象对传递损失的影响减小；仿真结果与实验结果基本吻合。该研究结果说明：对于膨胀腔类超材料，当刚度较小或者面积较大时，对其进行声固耦合分析是完全必要的。

Transmission loss of expansion chamber metamaterial

Acoustic metamaterials and artificial structures have been extensively studied. This superstructure was usually implemented using 3D printing technology. When the structural rigidity is small or the area is large, the acoustic effects caused by the acoustic-solid coupling do not conform to the design. In this paper, the effects of acoustic-solid coupling on the acoustic properties of expansion chamber acoustic metamaterials is investigated. The finite element analysis combined with the impedance tube experiment method is used to obtain the transmission loss, and the influence of the acoustic-solid coupling phenomenon on the transmission loss is analyzed. The results show that the frequency range of sound insulation of the thin-walled expansion chamber is inconsistent with the theoretical design without considering the acoustic-solid coupling. The transmission loss is significantly affected by the acoustic-solid coupling phenomenon. Increasing the wall thickness of the expansion chamber, reducing the inner diameter of the expansion chamber or selecting the metal material reduce the influence of the acoustic-solid coupling phenomenon on the transmission loss gradually decreases. The simulation results are basically consistent with the experiment results. This indicates that acoustic-solid coupling analysis of the expansion chamber metamaterial is absolutely necessary when the stiffness is small or the area is large.