局域共振声学超材料技术进展及应用展望

介绍了声学超材料主要有布拉格散射型声子晶体、局域共振型声学超材料等。布拉格散射型声子晶体通常需要其晶格常数与声波波长处于同一数量级时才能产生声波禁带,从而使得其应用领域受限。局域共振型声学超材料利用其共振单元的共振频率与声波频率接近时所产生的耦合作用而消耗声能,其尺寸比作用声波波长降低了2个数量级,从而实现了小尺寸声学超材料对长声波的控制。局域共振声学超材料采用特殊的声学结构单元设计,使其在常规介质中具有一些超常物理特性,如负折射、负质量密度等;其在低频段具有声学禁带,在该禁带频率范围内将阻止声波传递。局域共振声学超材料已发展出了具有谐振特性的声学结构单元、表面附加局域共振单元板结构声学超材料、薄膜型声学超材料等结构形式。局域共振声学超材料的研究和发展为低频降噪提供了新的途径。

Technical Progress and Application Prospect of Locally Resonant Sonic Metamaterials

Bragg scattering phonon crystal and locally resonant acoustic metamaterials were introduced. In order to generate noise reduction, the lattice constant of Bragg scattering phonon crystal should be of the same order of magnitude as the wavelength of the sound wave, therefore, its application field is limited. Locally resonant acoustic metamaterials consume sound energy by coupling its own resonant frequencies with those of sound waves at close range. Its size is two orders of magnitude smaller than the wavelength of sound wave; thus, the control of low-frequency noise by small-size acoustic metamaterials is realized. Locally resonant acoustic metamaterials have some extraordinary physical characteristic in the conventional medium for their special acoustic structural units, such as negative refraction and negative mass density. Especially in low frequency band, they have acoustic forbidden band in which the sound wave transmission is prohibited. Acoustic structural unit having resonant characteristics has been developed. Surface-mounted resonant element plate structures and thin film acoustic metamaterials are the normal types of locally resonant acoustic metamaterials. Their research and development provide a new method for low-frequency noise control.