Low frequency sound attenuation in a flow duct using a thin slow sound material

Aurégan, Yves; Farooqui, Maaz; Groby, Jean‐Philippe

doi:10.1121/1.4951028

Cited by 29 publications

(18 citation statements)

References 21 publications

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“…For the future aircrafts, there is a need for efficient treatments at low frequencies with small thickness. That is why other materials, like micro-perforated plate 2,3 , extended Helmholtz resonator 4 or slow sound materials [5][6][7] , which uses folded side branch quarter wavelength resonators to reduce the effective compressibility of the fluid, have been used to enhance sound attenuation in a duct with a grazing flow.…”

Section: Introductionmentioning

confidence: 99%

Sound attenuation optimization using metaporous materials tuned on exceptional points

Xiong¹,

Nennig²,

Aurégan³

et al. 2017

The Journal of the Acoustical Society of America

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A metamaterial composed of a set of periodic rigid resonant inclusions embedded in a porous lining is investigated to enhance the sound attenuation in an acoustic duct at low frequencies. A transmission loss peak is observed on the measurements and corresponds to the crossing of the lower two Bloch modes of an infinite periodic material. Numerical parametric studies show that the optimum modal attenuation can be achieved at the exceptional point in the parameter plane of inclusion position and frequency, where the two lower modes merge.

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Section: Introductionmentioning

confidence: 99%

Sound attenuation optimization using metaporous materials tuned on exceptional points

Xiong¹,

Nennig²,

Aurégan³

et al. 2017

The Journal of the Acoustical Society of America

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“…One of the main problems facing physicist and engineers working in the field of metamaterials is to achieve vibration damping and control over large, low frequency ranges. This is true in fields ranging from noise absorption [1][2][3][4] to seismic wave abatement [5,6]. Phononic crystals (PCs) and acoustic metamaterials (AMMs), generally made of periodically distributed inclusions in a matrix (or hosting material), are of particular interest because of their ability to act as stop-band filters, i.e.…”

Section: Introductionmentioning

confidence: 99%

Experimental Observation of a Large Low-Frequency Band Gap in a Polymer Waveguide

et al. 2018

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The quest for large and low frequency band gaps is one of the principal objectives pursued in a number of engineering applications, ranging from noise absorption to vibration control, to seismic wave abatement. For this purpose, a plethora of complex architectures (including multi-phase materials) and multi-physics approaches have been proposed in the past, often involving difficulties in their practical realization.To address this issue, in this work we propose an easy-to-manufacture design able to open large, low frequency complete Lamb band gaps exploiting a suitable arrangement of masses and stiffnesses produced by cavities in a monolithic material. The performance of the designed structure is evaluated by numerical simulations and confirmed by Scanning Laser Doppler Vibrometer (SLDV) measurements on an isotropic polyvinyl chloride plate in which a square ring region of cross-like cavities is fabricated. The full wave field reconstruction clearly confirms the ability of even a limited number of unit cell rows of the proposed design to efficiently attenuate Lamb waves. In addition, numerical simulations show that the structure allows to shift of the central frequency of the BG through geometrical modifications. The design may be of interest for applications in which large BGs at low frequencies are required.

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“…Moreover, in many engineering applications, a grazing flow is present and its effect on the impedance of the material is inversely proportional to σ [17]. For instance, it was experimentally shown [18] that the efficiency of a thin slow-sound metamaterial with σ = 0.023 was divided by 100 in the presence of a grazing flow with a Mach number of 0.2. Therefore, in the case of high sound levels or in the presence of flow, the additional constraint of having a high open area ratio must be added in the design of structures that are thin and absorbent at low frequency.…”

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confidence: 99%

Ultra-thin low frequency perfect sound absorber with high ratio of active area

Aurégan

2018

Applied Physics Letters

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A concept of ultra-thin low frequency perfect sound absorber is proposed and demonstrated experimentally. To minimize non-linear effects, an high ratio of active area to total area is used to avoid large localized amplitudes. The absorber consists of three elements: a mass supported by a very flexible membrane, a cavity and a resistive layer. The resonance frequency of the sound absorber can be easily adjusted just by changing the mass or thickness of the cavity. A very large ratio between wavelength and material thickness is measured for a manufactured perfect absorber (ratio = 201) . It is shown that this high sub-wavelength ratio is associated with narrowband effects and that the increase in the sub-wavelength ratio is limited by the damping in the system.

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Low frequency sound attenuation in a flow duct using a thin slow sound material

Cited by 29 publications

References 21 publications

Sound attenuation optimization using metaporous materials tuned on exceptional points

Sound attenuation optimization using metaporous materials tuned on exceptional points

Experimental Observation of a Large Low-Frequency Band Gap in a Polymer Waveguide

Ultra-thin low frequency perfect sound absorber with high ratio of active area

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