Pundir Anil, Gupta Arpan, Nag Sarthak
Acoustics and Vibration Laboratory, School of Mechanical and Materials Engineering, IIT Mandi, Kamand, Mandi, Himachal Pradesh, 175005, India.
Department of Mechanical Engineering, IIT Delhi, Hauz Khas, Delhi, 110016, India.
Sci Rep. 2024 Oct 14;14(1):24011. doi: 10.1038/s41598-024-71737-0.
Active acoustic metamaterials (AAMM) have garnered special attention because of their potential as multi-function devices. In this direction, the present article demonstrates a novel AAMM that can be programmed as a multi-functional Active Acoustic Meta-device (AAMD) that can switch functionalities between Acoustic Switch (AS), Acoustic Lens (AL), and Acoustic Barrier (AB). Functionality: AL corresponds to the wave vector space, and AS and AB correspond to the frequency space of the proposed AAMM. Additional functionality, such as acoustic logic gates in phase space, is also envisaged. The proposed design is found to change the dispersion diagram by acquiring different configurations while keeping the basic design parameters constant. These design parameters include constituent elements, lattice constants, and filling fractions. Further, for the said functionalities, the proposed AAMM does not rely on the deformation characteristics of the constituents. It rather capitalises on the possible relative displacements of the scatterers. As an AL, AAMM demonstrates zero angle refraction, i.e., collimation, and negative refraction of the transmitted beam at a given angle of incidence over a frequency range of 200 kHz (22.22% of the applied frequency sweep, a.f.s.). AB is shown to attenuate acoustic energy over a frequency range of 700 kHz (77.78% of a.f.s.) compared to its reference and foundation design, a statically designed Phononic Crystal (PnC). Furthermore, as AS, it operates over the entire range of applied frequency sweep (100 kHz to 1000 kHz), i.e., over the frequency range of 900 kHz (100% of a.f.s.).
有源声学超材料（AAMM）因其作为多功能器件的潜力而备受关注。在这个方向上，本文展示了一种新型的AAMM，它可以被编程为多功能有源声学超器件（AAMD），能够在声开关（AS）、声透镜（AL）和声屏障（AB）之间切换功能。功能：AL对应于波矢空间，而AS和AB对应于所提出的AAMM的频率空间。还设想了其他功能，如相空间中的声学逻辑门。发现所提出的设计在保持基本设计参数不变的情况下，通过获取不同的配置来改变色散图。这些设计参数包括组成元素、晶格常数和填充率。此外，对于上述功能，所提出的AAMM不依赖于组成部分的变形特性。相反，它利用了散射体可能的相对位移。作为一个AL，AAMM在200 kHz的频率范围内（占应用频率扫描范围的22.22%），对于给定的入射角，展示了零角度折射，即准直，以及透射光束的负折射。与它的参考和基础设计，即静态设计的声子晶体（PnC）相比，AB在700 kHz的频率范围内（占应用频率扫描范围的77.78%）显示出对声能的衰减。此外，作为AS，它在整个应用频率扫描范围内（100 kHz至1000 kHz）运行，即在900 kHz的频率范围内（占应用频率扫描范围的100%）运行。
