%0 Journal Article %T Enhancing the absorption coefficient of a backed rigid frame porous layer by embedding circular periodic inclusions %+ Laboratoire d'Acoustique de l'Université du Mans (LAUM) %+ Huntsman Europe, Everslaan 45, 3078 Everberg, Belgium %+ Laboratory of Acoustics and Thermal Physics, K.U. Leuven %A Groby, J.-P. %A Dazel, Olivier %A Duclos, Aroune %A Boeckx, L. %A Kelders, L. %< avec comité de lecture %@ 0001-4966 %J Journal of the Acoustical Society of America %I Acoustical Society of America %V 130 %N 6 %P 3771-3780 %8 2011-12 %D 2011 %R 10.1121/1.3652865 %K Phononic crystal %K Bloch wave %K Gratings %K Finite-element analysis %K Geometrical optics %K Vector fields %K Optical absorption %K Acoustical properties %K Wave mechanics %K Speed of sound %Z Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph]Journal articles %X The acoustic properties of a porous sheet of medium static air flow resistivity (around 10 000Nms-4), in which a periodic set of circular inclusions is embedded and which is backed by a rigid plate, are investigated. The inclusions and porous skeleton are assumed motionless. Such a structure behaves like a multi-component diffraction grating. Numerical results show that this structure presents a quasi-total (close to unity) absorption peak below the quarter-wavelength resonance of the porous sheet in absence of inclusions. This result is explained by the excitation of a complex trapped mode. When more than one inclusion per spatial period is considered, additional quasi-total absorption peaks are observed. The numerical results, as calculated with the help of the mode-matching method described in this paper, agree with those calculated using a finite element method. %G English %L hal-02458855 %U https://hal-univ-lemans.archives-ouvertes.fr/hal-02458855 %~ CNRS %~ UNIV-LEMANS %~ LAUM