2010/07/19 by Jean‐Philippe Groby, Groby, Jean-Philippe, Olivier Dazel +7
Engineering · Materials Science · #Classical Physics (physics.class-ph) #FOS: Physical sciences #Material Properties and Processing #Surface Roughness and Optical Measurements #Textile materials and evaluations
paper · pdf · doi:10.48550/arxiv.1007.3177
openalex publication_date 2010/07/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The acoustic properties of a porous sheet of medium resistivity backed by a rigid plate in which are embedded a periodic set of circular inclusions is investigated. Such a structure behaves like a multi-component diffraction gratings. Numerical results show that this structure presents a quasi-total absorption peak below the essential spectrum, i.e. below the frequence of the fundamental quarter-wavelength resonance of the porous sheet in absence of inclusions. This result is explained either by the excitation of a complex trapped mode, or by the increase of viscous loss associated with a larger velocity gradient inside the layer at the modified quarter-wavelength resonance frequency. When more than one inclusion per spatial period are considered, additional quasi-total frequency peak are observed. The numerical results as calculated with the help of the mode-matching method described in the paper agree those as calculated with the help of a Finite Element method.