Manipulation of Low-Frequency Sound with a Tunable Active Metamaterial Panel

Gao, Nan; Dong, Z.-C.; Mak, Ho Yiu; Sheng, Ping

doi:10.1103/physrevapplied.17.044037

Cited by 9 publications

(1 citation statement)

References 33 publications

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“…For airborne sound, the constraints of the causality principle dictate that the thickness of the sample must satisfy the following relationship [22] : 1 where is the bulk modulus of air, is the effective bulk modulus of the sample and represents the absorption spectrum with respect to the wavelength . Numerous researchers have attempted to achieve subwavelength acoustic structure design within the con nes of the minimum thickness limit [23][24][25][26][27][28][29][30][31][32][33][34] . Recently, Mak et al [35] used a soft boundary to circumvent the minimum thickness…”

Section: Introductionmentioning

confidence: 99%

Deep Subwavelength Broadband Sound Absorption by a Buckled Plate Resonator

Han

Xing

2023

Preprint

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The absorption performance and the sample thickness need to satisfy the causal relation, and the sound absorption bandwidth of a thin layer structure is often very narrow to achieve high sound absorption at low frequency. In this paper, a buckled plate resonator is proposed to achieve the low frequency broadband sound absorption in the deep subwavelength range. The resonator consists of an air-tight back cavity sealed by an elastic circular thin plate. A uniform in-plane compressive force is applied on the thin plate to make the plate buckling produce negative stiffness, and the resonator operates in the pre-buckling state. By adjusting the structural stiffness, the buckled plate resonator achieves the purpose of adjusting Beff and B0, which weakens the causal principle requirement of minimum acoustic structure thickness and realizes broadband low-frequency sound absorption. The final experimental results show that one 3mm(λ/220) back cavity, 0.89 sound absorption is achieved at 515Hz, and the corresponding relative sound absorption bandwidth is 19.4%. From the causal relation, the calculated minimum sample thickness is 6.7mm for the observed absorption spectrum. Compared with traditional plate-type acoustic metamaterials, which achieve low-frequency sound absorption by increasing the mass, the absorption bandwidth is too narrow due to the influence of the quality factor Qm, our work provides a design paradigm for the low frequency broadband acoustic absorbers.

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Section: Introductionmentioning

confidence: 99%

Deep Subwavelength Broadband Sound Absorption by a Buckled Plate Resonator

Han

Xing

2023

Preprint

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Topology optimization of chiral metamaterials with application to underwater sound insulation

Wang,

Zhao,

Wang

et al. 2024

Appl. Math. Mech.-Engl. Ed.

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Chiral metamaterials have been proven to possess many appealing mechanical phenomena, such as negative Poisson’s ratio, high-impact resistance, and energy absorption. This work extends the applications of chiral metamaterials to underwater sound insulation. Various chiral metamaterials with low acoustic impedance and proper stiffness are inversely designed using the topology optimization scheme. Low acoustic impedance enables the metamaterials to have a high and broadband sound transmission loss (STL), while proper stiffness guarantees its robust acoustic performance under a hydrostatic pressure. As proof-of-concept demonstrations, two specimens are fabricated and tested in a water-filled impedance tube. Experimental results show that, on average, over 95% incident sound energy can be isolated by the specimens in a broad frequency range from 1 kHz to 5 kHz, while the sound insulation performance keeps stable under a certain hydrostatic pressure. This work may provide new insights for chiral metamaterials into the underwater applications with sound insulation.

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