用于低频隔声的类Fano共振型声学超材料设计

Design of Fano resonance-like acoustic metamaterials for low-frequency acoustic isolation

  • 摘要: 由于当前铁路声屏障存在低频降噪效果差、降噪量较低及通风性能不佳的情况,本文研究创新设计了一种基于类Fano共振原理的声学超材料,旨在显著提升对低频噪声的隔绝效果。利用基于离散状态的共振散射和连续状态的背景散射之间的干扰,从而诱导出类Fano的非对称传输剖面。该超材料单胞为环绕型迷宫结构,将其周期性排列后得到类Fano共振的低频隔声型超材料声屏障,本结构设计为兼顾隔声效果和可通风全向性的几何形状,中空部分还能够节省成本。首先介绍了超材料单胞的几何构型以及传声理论,分析了结构参数对所提出声学超材料性能的影响,为优化其声学特性提供了重要依据。另外对超材料性能进行数值模拟与仿真分析,深入探究其声学特性,计算出结构在20, 2900Hz时,平均声传输损失达到50 dB左右。将超材料单元周期性排列嵌套在单元板内组成声屏障模型,发现超材料单元个数的增加不会影响声屏障隔声性能。最后将3D打印的声学超材料进行声学实验验证了仿真结果的准确性,为声屏障设计与工程应用提供了思路。

     

    Abstract: Due to the poor low-frequency noise reduction, low noise reduction and poor ventilation performance of the current railroad sound barriers, the research in this paper innovatively designs an acoustic metamaterial based on the Fano-like resonance principle, aiming to significantly enhance the insulation effect on low-frequency noise. The interference between the resonant scattering based on the discrete state and the background scattering in the continuous state is utilized, thus inducing a Fano-like asymmetric transmission profile. The metamaterial single cell is a wrap-around labyrinth structure, and the Fano resonance-like low-frequency acoustic isolation type metamaterial acoustic barrier is obtained by arranging it periodically. The structure is designed to be a geometry that takes into account the acoustic isolation effect and ventilatable omni-directionality, and the hollow part is also able to save the cost. Firstly, the geometrical configuration of the metamaterial cell and the theory of sound transmission are introduced, and the influence of structural parameters on the performance of the proposed acoustic metamaterial is analyzed, which provides an important basis for optimizing its acoustic properties. In addition, numerical simulation and simulation analysis of the metamaterial properties are carried out to explore its acoustic properties in depth, and the average acoustic transmission loss of the structure is calculated to be about 50 dB at 20,2900 Hz. The acoustic barrier is modeled by periodically arranging the metamaterial units nested inside the unit plate, and it is found that the increase in the number of metamaterial units does not affect the acoustic performance of the acoustic barrier. Finally, the 3D printed acoustic metamaterials are subjected to acoustic experiments to verify the accuracy of the simulation results, which provides ideas for sound barrier design and engineering applications.

     

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