Broadening the attenuation range of acoustic metafoams through graded microstructures. (29th September 2020)

• Record Type: Journal Article
• Authors: Lewińska, M.A.; van Dommelen, J.A.W.; Kouznetsova, V.G.; Geers, M.G.D.
• Is Part Of: Journal of sound and vibration. Volume 483(2020)
• Publication Date: 2020-09-29
• Subjects: Computational homogenisation -- Acoustic metamaterials -- Poro-elastic materials -- Local resonance -- Visco-thermal dissipation -- Acoustic foams -- Metafoams -- Graded materials; Sound -- Periodicals; Vibration -- Periodicals; Son -- Périodiques; Vibration -- Périodiques; Sound; Vibration; Periodicals; Electronic journals; 620.205
• DOI: 10.1016/j.jsv.2020.115472
• Languages: English
• ISSNs: 0022-460X

Abstract

Abstract: Low frequency sound attenuation is a challenging task, because of the severe mass, stiffness and volume constraints on the absorbing and/or reflecting barriers. Recently, significant improvements in low frequency sound attenuation has been achieved by introducing the acoustic metafoam concept, which combines the mechanism of conventional acoustic foams - high viscothermal dissipation - with the working principle of locally resonant acoustic metamaterials - wave attenuation at low frequencies. However, the attenuation improvement provided by periodic materials containing identical resonators is confined to a narrow frequency range. To overcome this limitation, graded acoustic metafoams are proposed and studied here, where a distribution of local resonators with varying properties (mass and stiffness) is introduced. It is demonstrated that, through a suitable design of mass and stiffness distribution of the resonators, the broadening of the frequency attenuation ranges can be effectively achieved. Graded acoustic metafoams are, therefore, a natural development direction for achieving broad frequency attenuation zones.