Broadening the attenuation range of acoustic metafoams through graded microstructures

Mirka A. Lewinska, J.A.W. (Hans) van Dommelen (Corresponding author), Varvara G. Kouznetsova, Marc G.D. Geers

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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.

Original languageEnglish
Article number115472
Number of pages13
JournalJournal of Sound and Vibration
Volume483
DOIs
Publication statusPublished - 29 Sep 2020

Keywords

  • Acoustic foams
  • Acoustic metamaterials
  • Computational homogenisation
  • Graded materials
  • Local resonance
  • Metafoams
  • Poro-elastic materials
  • Visco-thermal dissipation

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