Kim Jiwan, Jeon Wonju
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
J Acoust Soc Am. 2021 Apr;149(4):2323. doi: 10.1121/10.0003435.
We propose a sound-absorbing nonplanar metasurface by considering locally different incidence angles along the metasurface. Perfect sound absorption is realized with the aid of hybrid resonance between two different subwavelength Helmhwoltz resonators comprising a unit cell. We theoretically investigate the effect of incidence angles on the sound absorption of the unit cells, and present a design method of the nonplanar metasurface that achieves perfect absorption by considering locally different incidence angles along the metasurface. The perfect absorption of plane sound waves on nonplanar surfaces is numerically demonstrated at the target frequency of 1 kHz. The numerical results show that at least 99.8% of the incident wave energy is absorbed by the designed metasurfaces with a thickness of λ/24. A nonplanar metasurface is fabricated via three-dimensional printing, and perfect sound absorption is experimentally validated at the target frequency of 1 kHz. Furthermore, we design nonplanar metasurfaces that can perfectly absorb cylindrical sound waves when a line source is located near the metasurface. While previous sound-absorbing metasurfaces focused only on planar surfaces, the proposed method achieves perfect sound absorption on nonplanar surfaces, expanding the range of practical applications in various industrial areas.
我们通过考虑沿超表面局部不同的入射角，提出了一种吸声非平面超表面。借助由一个单元结构组成的两个不同亚波长亥姆霍兹谐振器之间的混合共振，实现了完美吸声。我们从理论上研究了入射角对单元结构吸声的影响，并提出了一种非平面超表面的设计方法，该方法通过考虑沿超表面局部不同的入射角来实现完美吸收。在1kHz的目标频率下，通过数值模拟证明了非平面表面上平面声波的完美吸收。数值结果表明，厚度为λ/24的设计超表面至少吸收了99.8%的入射波能量。通过三维打印制造了一个非平面超表面，并在1kHz的目标频率下通过实验验证了完美吸声。此外，我们设计了非平面超表面，当线源位于超表面附近时，该超表面可以完美吸收柱面声波。虽然以前的吸声超表面仅关注平面表面，但所提出的方法在非平面表面上实现了完美吸声，扩大了在各个工业领域的实际应用范围。
