Active control of the dynamic density of acoustic metamaterials

Akl, W.; Baz, A.

doi:10.1016/j.apacoust.2021.108001

Cited by 9 publications

(8 citation statements)

References 23 publications

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“…The resulting outcome is a relatively broad tuneable effective density. This variation of active AMMs has been developed further in recent years, including implementing closed-loop control over the effective density of multi-cell systems [37] and demonstrating it experimentally [88]. This experimental meta-cell, shown in Figure 9b, achieved a wide range of effective density values (0.35-13 times that of the contained fluid medium).…”

Section: Active Metamaterialsmentioning

confidence: 95%

“…(b) Experimental set-up for an active AMM cell using piezoelectric membranes. A similar but more refined version of the experimental prototype in (a), with this example being more compact with additional embedded pressure sensors and closed-loop control [88] (Reprinted from Applied Acoustics, Volume 178, W. Akl and A. Baz., 'Active control of the dynamic density of acoustic metamaterials', Copyright (2021), with permission from Elsevier).…”

Section: Active Metamaterialsmentioning

confidence: 99%

“…(b) Experimental set-up for an active AMM cell using piezoelectric membranes. A similar but more refined version of the experimental prototype in (a), with this example being more compact with additional embedded pressure sensors and closed-loop control [88] Other actuation methods for active AMMs include mechanical energy, temp and applied magnetic fields. Helmholtz resonator-based devices can incorporate m ical plungers to change their internal cavity volume, resulting in a shift in acoust erties.…”

Section: Active Metamaterialsmentioning

confidence: 99%

“…Active AMMs are designed to have modifiable effects on the surrounding acoustic field; therefore, the changeable parameters are usually directly related to the equations for acoustic wave propagation. Bulk modulus and effective density are of specific interest, with a significant portion of active AMM research focused on allowing these parameters to be tuneable [27,28,30,32,88,99,100]. Many new tuneable devices build upon early AMMs, such as Helmholtz resonator arrays and periodic lattice structures, by incorporating active elements.…”

Section: Active Metamaterialsmentioning

confidence: 99%

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Additive Manufacture of Small-Scale Metamaterial Structures for Acoustic and Ultrasonic Applications

et al. 2021

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Acoustic metamaterials are large-scale materials with small-scale structures. These structures allow for unusual interaction with propagating sound and endow the large-scale material with exceptional acoustic properties not found in normal materials. However, their multi-scale nature means that the manufacture of these materials is not trivial, often requiring micron-scale resolution over centimetre length scales. In this review, we bring together a variety of acoustic metamaterial designs and separately discuss ways to create them using the latest trends in additive manufacturing. We highlight the advantages and disadvantages of different techniques that act as barriers towards the development of realisable acoustic metamaterials for practical audio and ultrasonic applications and speculate on potential future developments.

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Section: Active Metamaterialsmentioning

confidence: 95%

Section: Active Metamaterialsmentioning

confidence: 99%

“…(b) Experimental set-up for an active AMM cell using piezoelectric membranes. A similar but more refined version of the experimental prototype in (a), with this example being more compact with additional embedded pressure sensors and closed-loop control [88] Other actuation methods for active AMMs include mechanical energy, temp and applied magnetic fields. Helmholtz resonator-based devices can incorporate m ical plungers to change their internal cavity volume, resulting in a shift in acoust erties.…”

Section: Active Metamaterialsmentioning

confidence: 99%

Section: Active Metamaterialsmentioning

confidence: 99%

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Additive Manufacture of Small-Scale Metamaterial Structures for Acoustic and Ultrasonic Applications

et al. 2021

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“…achieved the goal of actively controlling sound propagation by controlling the equivalent density by embedding piezoelectric elements into the material. [ 199 ] He et al. used an active feedback control system for wave metamaterials to change the effective mass density and sound transmission under incident sound pressure.…”

Section: Active Acoustic Metamaterialsmentioning

confidence: 99%

Acoustic Metamaterials for Noise Reduction: A Review

Gao

Zhang

Deng

et al. 2022

Adv Materials Technologies

213

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Noise pollution has become a significant global problem in recent years. Unfortunately, conventional acoustic materials cannot offer substantial improvements in noise reduction. However, acoustic metamaterials are providing new solutions for controlling sound waves, and have huge potential for mitigating noise propagation in particular. Recently, owing to the rapid development of acoustic metamaterials, metamaterials for acoustic noise reduction have drawn the attention of researchers worldwide. These metamaterials are often both light and compact, and are excellent at reducing low‐frequency noise, which is difficult to control with conventional acoustic materials. Recent progress has illustrated that acoustic metamaterials effectively control sound waves, and optimizing their structure can enable functionality based on new physical phenomena. This review introduces the development of acoustic metamaterials, and summarizes the basic classification, underlying physical mechanism, application scenarios, and emerging research trends for both passive and active noise‐reduction metamaterials. Focusing on noise reduction, the shortcomings of current technologies are discussed, and future development trends are predicted. As our knowledge in this area continues to expand, it is expected that acoustic metamaterials will continue to improve and find more practical applications in emerging fields in the future.

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