Abstract
Acoustic metafoams are novel materials recently proposed for low frequency sound attenuation. The design of their microstructure is based on the combination of standard acoustic foams with locally resonant acoustic metamaterials. This results in improved sound attenuation properties due to the interaction between viscothermal dissipation effects and the local resonance effects at the pore level. In this paper, the non-standard behaviour of such a metafoam with a complex two-phase microstructure is analysed through a multiscale approach. The macroscopic problem is described by general balance equations and at the microscopic scale a detailed representation of the microstructure is considered. The frequency dependent effective properties are used to explain the extraordinary acoustic performance. The homogenisation approach is also validated using direct numerical simulations, showing that the homogenisation technique is adequate in modelling both viscothermal dissipation and the local resonance effect within the metafoam microstructure.
| Original language | English |
|---|---|
| Article number | 103805 |
| Number of pages | 9 |
| Journal | European Journal of Mechanics. A, Solids |
| Volume | 77 |
| DOIs | |
| Publication status | Published - 1 Sept 2019 |
Funding
The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme ( FP7/2007–2013 )/ERC grant agreement no 339392. Appendix The macroscopic constitutive relations (14), (15), (16) and (17), using the Voigt notation, and taking into consideration the unit cell symmetries, are expressed as: (36) [ σ x x s σ y y s σ z z s σ y z s σ x z s σ x y s ɛ f ] = [ C 11 C 12 C 13 0 0 0 − Ψ 1 s f C 12 C 11 C 13 0 0 0 − Ψ 2 s f C 13 C 13 C 33 0 0 0 − Ψ 3 s f 0 0 0 C 44 0 0 0 0 0 0 0 C 44 0 0 0 0 0 0 0 C 66 0 − Ψ 1 s f − Ψ 2 s f − Ψ 3 s f 0 0 0 − S f ] [ ∂ u x s ∂ x ∂ u y s ∂ y ∂ u z s ∂ z ∂ u y s ∂ z ∂ u x s ∂ z ∂ u x s ∂ y p f ] , (37) [ f x s f y s f z s u x f u y f u z f ] = [ − ω 2 M 1 s 0 0 K 1 s f 0 0 0 − ω 2 M 1 s 0 0 K 1 s f 0 0 0 − ω 2 M 3 s 0 0 K 3 s f K 1 s f 0 0 ( ω 2 ρ 0 f ) − 1 K 1 f 0 0 0 K 1 s f 0 0 ( ω 2 ρ 0 f ) − 1 K 1 f 0 0 0 K 3 s f 0 0 ( ω 2 ρ 0 f ) − 1 K 3 f ] [ u x s u y s u z s ∂ p f ∂ x ∂ p f ∂ y ∂ p f ∂ z ] .
Keywords
- Acoustic foams
- Acoustic metamaterials
- Computational homogenisation
- Local resonance
- Metafoams
- Poro-elastic materials
- Viscothermal dissipation
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