Controlling the effective surface mass density of membrane-type acoustic metamaterials using dynamic actuators
Controlling the effective surface mass density of membrane-type acoustic metamaterials using dynamic actuators
Membrane-type acoustic metamaterials (MAM) are thin and lightweight structures that offer exceptional low-frequency sound transmission loss (STL) values, which can exceed the corresponding mass-law significantly. Typically, the high STL of MAM is confined to a narrow frequency band, which is associated with the so-called anti-resonance. This narrow bandwidth reduces the range of potential noise control applications for MAM. To potentially overcome this challenge, this paper presents an investigation into actively controlling the effective surface mass density of MAM by actuating the MAM with a force that is correlated to the acoustic pressure difference acting on the MAM. In particular, it is shown using theoretical and numerical methods that the anti-resonance frequency of MAM can be adjusted over a wide frequency range by passing the incident sound pressure through an adjustable gain. A simple analytical model to predict the frequency shifting, depending on the gain value, is derived. A realization of this concept is further studied, consisting of a circular MAM with a small electrodynamic actuator (to apply a force to the MAM) and a microphone in front of the MAM (to estimate the pressure difference). Finally, experimental results from impedance tube measurements are used to validate the proposed analytical model.
961-971
Langfeldt, Felix
2bf86877-f2cd-4c35-be0f-e38a718a915c
Cheer, Jordan
8e452f50-4c7d-4d4e-913a-34015e99b9dc
7 February 2023
Langfeldt, Felix
2bf86877-f2cd-4c35-be0f-e38a718a915c
Cheer, Jordan
8e452f50-4c7d-4d4e-913a-34015e99b9dc
Langfeldt, Felix and Cheer, Jordan
(2023)
Controlling the effective surface mass density of membrane-type acoustic metamaterials using dynamic actuators.
The Journal of The Acoustical Society of America, 153 (2), .
(doi:10.1121/10.0017214).
Abstract
Membrane-type acoustic metamaterials (MAM) are thin and lightweight structures that offer exceptional low-frequency sound transmission loss (STL) values, which can exceed the corresponding mass-law significantly. Typically, the high STL of MAM is confined to a narrow frequency band, which is associated with the so-called anti-resonance. This narrow bandwidth reduces the range of potential noise control applications for MAM. To potentially overcome this challenge, this paper presents an investigation into actively controlling the effective surface mass density of MAM by actuating the MAM with a force that is correlated to the acoustic pressure difference acting on the MAM. In particular, it is shown using theoretical and numerical methods that the anti-resonance frequency of MAM can be adjusted over a wide frequency range by passing the incident sound pressure through an adjustable gain. A simple analytical model to predict the frequency shifting, depending on the gain value, is derived. A realization of this concept is further studied, consisting of a circular MAM with a small electrodynamic actuator (to apply a force to the MAM) and a microphone in front of the MAM (to estimate the pressure difference). Finally, experimental results from impedance tube measurements are used to validate the proposed analytical model.
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JASA-08792_accepted
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Langfeldt_Cheer_2023_Controlling the effective surface mass density of membrane-type acoustic
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Accepted/In Press date: 25 January 2023
e-pub ahead of print date: 7 February 2023
Published date: 7 February 2023
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Funding Information:
The research of F.L. was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the framework of the Walter Benjamin Programme (Grant No. 455631459). The authors acknowledge the use of the IRIDIS High Performance Computing Facility and associated support services at the University of Southampton in the completion of this work.
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© 2023 Acoustical Society of America.
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Local EPrints ID: 475033
URI: http://eprints.soton.ac.uk/id/eprint/475033
ISSN: 0001-4966
PURE UUID: 9ef4e061-0a7f-4511-aba3-66e730bd373d
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Date deposited: 09 Mar 2023 17:33
Last modified: 17 Mar 2024 04:11
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