Abstract
Acoustic metamaterial science is an emerging field at the frontier of modern acoustics. It provides a prominent platform for acoustic wave control in subwavelength-sized metadevices or metasystems. However, most of the metamaterials can only work in a narrow frequency band once fabricated, which limits the practical application of acoustic metamaterials. This paper highlights some recent progress in tunable acoustic metamaterials based on various modulation techniques. Acoustic metamaterials have been designed to control the attenuation of acoustic waves, invisibility cloaking, and acoustic wavefront engineering, such as focusing via manipulating the acoustic impedance of metamaterials. The reviewed techniques are promising in extending the novel acoustics response into wider frequency bands, in that tunable acoustic metamaterials may be exploited for unusual applications compared to conventional acoustic devices.
Highlights
Metamaterials are rationally designed artificial structures with periodically or non-periodically arranged subwavelength elements [1,2,3,4], which exhibit unusual properties beyond natural occurring media [5]
acoustic metamaterials (AMMs) are a new type of man-made structure that regulate acoustic behavior, resulting in negative effective mass densities and negative effective bulk modulus based on localized resonance mechanisms as well as extraordinary scattering properties [54]
We provide a survey of the recently developed tunable acoustic metamaterials based on various modulation techniques, including acoustic metamaterials with piezoelectric materials, mechanically controllable components, and with electric and magnetic biasing
Summary
Metamaterials are rationally designed artificial structures with periodically or non-periodically arranged subwavelength elements [1,2,3,4], which exhibit unusual properties beyond natural occurring media [5]. Since sound waves and electromagnetic waves have a large amount of analogical characteristics, the supernatural phenomena such as negative refraction [50], invisible cloak [51,52], and wavefront manipulation [53] occur through specific designed acoustic composite structures, i.e., acoustic metamaterials (AMMs). AMMs are a new type of man-made structure that regulate acoustic behavior, resulting in negative effective mass densities and negative effective bulk modulus based on localized resonance mechanisms as well as extraordinary scattering properties [54]. When both situations expands withexerted exertedpressure pressure when the effective bulk modulus is negative [86] When both occur simultaneously, a frequency range appeared in which in propagation in the AMM is AMM allowed; situations occur simultaneously, a frequency range appeared which propagation in the is allowed; the acoustic structure is classified as a double negative acoustic metamaterial. New classes of AMMs with tunable band gaps are reviewed
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