搜索

x
中国物理学会期刊

基于低额外相位延迟声学超材料与莫尔效应的可调声场器件设计及验证

Design and Verification of Tunable Acoustic Field Devices Based on Low additional Phase Delay Acoustic Metamaterials and Moiré Effect

PDF
导出引用
  • 传统声学超材料在设计完成之后结构与性能往往固定,这对声学超材料的应用产生了限制。尽管基于莫尔效应的声学超材料已经为声波动态调控提供了新思路,但串联单元间的耦合效应会引入显著的额外相位延迟,干扰波前相位的精准调控。本文设计了一种可串联使用的低耦合声学超材料单元。该单元通过插板长度的指数式渐变实现声阻抗的平滑过渡,相较于传统空间折叠结构,该设计还能大幅降低串联时产生的额外相位延迟,从而解决双层可调超表面设计中的耦合问题。此外该结构还具有大于0.8的声压透射系数及0–360° 的全相位调控。基于上述优势,本文结合莫尔效应设计了折射角可调的异常折射声学超材料,折射角实现从0-51°的调节,理论折射角与仿真折射角最大误差仅4%。此外还设计了焦点坐标可调的声聚焦声学超材料,实现焦点横坐标0 mm到116 mm的偏移。这项工作拓展了可重构声学超材料的应用范围,为多功能声波调控提供了新思路。

    Traditional acoustic metamaterials are limited by their fixed structures, usually enabling only a single acoustic field manipulation function. To alter their acoustic field regulation performance, redesign and remanufacturing are required, which restricts the practical applications of acoustic metamaterials. Although acoustic metamaterials based on the moiré effect have provided a novel strategy for the dynamic manipulation of acoustic waves, the coupling effect between cascaded units can introduce significant additional phase delay, interfering with the precise manipulation of wavefront phase. To address this, we propose a cascadable exponentially graded acoustic metamaterial (EGAM) based on the space-coiling structure. Its key design is the exponential gradient of insert plate lengths, achieving smooth acoustic impedance transition and suppressing additional phase delay during cascading. When used individually, the metamaterial exhibits a low transmission coefficient; however, after cascading, the minimum sound pressure transmission coefficient exceeds 0.8, meeting the requirements of acoustic transmission. A single unit of the structure can achieve a full 0–360° phase adjustment, with the phase delay showing a linear correlation with the structural parameters. Even under broadband conditions, the structure maintains excellent phase manipulation capability and transmission performance. Compared with traditional space-coiling structures, the additional phase delay induced by the coupling effect between units during cascading is negligible. Leveraging this advantage of minimal additional phase delay, an abnormal refraction acoustic metamaterial with tunable refraction angles is designed by combining the Moiré effect. Verified through numerical simulations and experimental measurements, the refraction angle can be continuously tuned from 0° to 51°, with a maximum error of only 4% between the theoretical and simulation results. Furthermore, the same design strategy is employed to realize tunable acoustic focusing. By analyzing the error between the ideal phase distribution and the actual phase distribution of the cascaded structure, the horizontal coordinate of the focusing point is successfully shifted from 0–116 mm, with a maximum horizontal error of 2.6%. Both the tunable refraction angle and focusing position achieved in this work are in high consistency with the theoretical predictions. This study expands the application scope of reconfigurable acoustic metamaterials and provides a new perspective for multifunctional acoustic wave manipulation.

    目录

    返回文章
    返回
    Baidu
    map