A design technique for transforming statically designed phononic crystals and metamaterials into multifunctional, programmable active acoustic meta-devices

Abstract

The active tuning of the bandgaps induced by the acoustic metamaterials has sparked significant interest among researchers. It opens up possibilities for programmable, multifunctional acoustic meta-devices. The static design of acoustic metamaterials, however, has limited automation capabilities, particularly for controlling sound propagation through the elastic solids. Designing acoustic metamaterials with fluid as the host medium, specifically air, significantly reduces these constraints. Given this observation, the present work demonstrates a novel design technique that transforms a Phononic Crystal (PnC) into an Active Acoustic Meta-device (AAMD). The designed AAMD has been demonstrated as programmable and multi-functional. It functions as an acoustic barrier over around 94% of the applied frequency sweep (a.f.s)., 300–3500 Hz. As an acoustic transmitter, it magnifies acoustic energy over around 50% of the a.f.s. Similarly, it functions as an acoustic switch over 100% of the a.f.s. This metadevice distinguishes itself by solely utilizing a two-phase material system and employing basic design elements, rather than common resonating elements, such as Helmholtz resonators or softer coatings.