Enhancement of the absorption of a backed rigid frame porous layer using a 2-dimensional periodic multi-irregularities rigid backing

Bruno Brouard (1) , Jean-Philippe Groby (1) , Olivier Dazel , Benoit Nennig (2) , Luc Kelders

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans
2 Roberval - Roberval

The acoustic properties of a porous layer with a medium flow resistivity and backed by a rigid plate containing periodic rectangular irregularities, creating a multi-component diffraction grating, are investigated. It extends the work proposed in [Journal of the Acoustical Society of America 127, 2865-2874, 2010], to a 3D problem involving a 2D grating. Numerical and experimental results show that the structure possesses possibly total absorption peaks at the frequencies of the modified mode of the layer and/or of the trapped mode associated to the irregularities, when designed as proposed. These results is explained by an analysis of the acoustic response of the whole structure and especially by the modal analysis of the configuration. When more than one irregularity per spatial period is considered, additional higher frequency peaks are observed.

Mots clés: porous; absorption; grating

Domaines: Acoustique [physics.class-ph]

Bruno Brouard, Jean-Philippe Groby, Olivier Dazel, Benoit Nennig, Luc Kelders. Enhancement of the absorption of a backed rigid frame porous layer using a 2-dimensional periodic multi-irregularities rigid backing. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811030⟩