Broadband low-frequency noise reduction using Helmholtz resonator-based metamaterial
| Autor: | Jhalu Gorain, Chandramouli Padmanabhan |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Acoustics and Ultrasonics Mechanical Engineering Acoustics Attenuation Transmission loss Public Health Environmental and Occupational Health Aerospace Engineering Metamaterial Building and Construction Industrial and Manufacturing Engineering law.invention Resonator law Automotive Engineering Broadband Acoustic impedance Helmholtz resonator Electromagnetic reverberation chamber |
| Zdroj: | Noise Control Engineering Journal. 69:351-363 |
| ISSN: | 0736-2501 |
| DOI: | 10.3397/1/376932 |
| Popis: | Achieving broadband noise attenuation at low frequencies is still a significant challenge. Helmholtz resonators offer good low-frequency noise attenuation but are effective only over a narrow band; the cavity volume required at these frequencies is also larger. This article proposes a new broadband acoustic metamaterial (AMM) absorber, which uses polyurethane (PU) foam embedded with small-size resonators tuned to different frequencies. The AMM design is achieved in three phases: (1) develop a transfer-matrix-based one-dimensional model for a resonator with intruded neck; (2) use this model to develop a novel band broadening method, to select appropriate resonators tuned to different frequencies; and (3) construct a unit cell metamaterial embedded with an array of resonators into PU foam. A small-size resonator tuned to 415 Hz is modified, by varying the intrusion lengths of the neck, to achieve natural frequencies ranging from 210 to 415 Hz. Using the band broadening methodology, 1 unit cell metamaterial is constructed; its effectiveness is demonstrated by testing in an acoustic impedance tube. The broadband attenuation characteristics of the constructed unit cell metamaterial are shown to match well with the predicted results. To demonstrate further the effectiveness of the idea, a metamaterial is formed using 4 periodic unit cells and is tested in a twin room reverberation chamber. The transmission loss is shown to improve significantly, at low frequencies, due to the inclusion of the resonators. © 2021 Institute of Noise Control Engineering. |
| Databáze: | OpenAIRE |
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