Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7152570 | Applied Acoustics | 2016 | 6 Pages |
Abstract
The optimization of acoustic absorption by metaporous materials made of complex unit cells with 2D resonant inclusions is realized using genetic algorithm. A nearly total absorption over a wide frequency band can be obtained for thin structures, even for frequencies below the quarter wavelength resonances i.e., in a sub-wavelength regime. The high absorption performances of this material are due to the interplay of usual visco-thermal losses, local resonances and trapped modes. The density of resonant and trapped modes in this dissipative porous layer, is a key parameter for broadband absorption. The best configurations and critical coupling conditions are found by genetic algorithm optimization. Several types of resonators are included gradually in the studied configurations (split-rings, Helmholtz resonators, back cavities) with increasing complexity. The optimization leads to a metaporous structure with a 2-cm sub-wavelength layer thickness, exhibiting a nearly total absorption between 1800Â Hz and 7000Â Hz. The influence of the incidence angle on the absorption properties is also shown.
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Authors
C. Lagarrigue, J.-P. Groby, O. Dazel, V. Tournat,