0000000000917966
AUTHOR
Philippe Leclaire
Recent Highlights on the Parallel Transfer Matrix Method (Ptmm)
International audience; Recently, an extension of the transfer matrix method (TMM) to calculate absorption coefficient and transmission loss of acoustic systems in parallel (one next to each other and not one after the other) has been published [1]. This method (P-TMM) is based on the continuity of flow and pressure on each side of the stack. To comply with these constraints, assumptions must be set: there is only plane waves that propagate, no exchange is allowed between the elements of the stack, the stack is smaller than the wavelength. Further progress has been made. Firstly, a comparison with the method of the sum of admittances (ASM) [2] will be presented. Then, a further extension of…
Holes Interaction and Heterogeinity Distribution Effect for a Multiperforated Plate
International audience; Originally used to protect classical sound absorbing materials from environmental degradation, multi-perforated plates are considered to be one of the next generation soundproof solutions. This paper investigates the effects of holes interaction and heterogeneity distribution on the acoustical properties of a multi-perforated plate. These effects are observable on the specimens with closely separated holes. Multi-perforated plates with different center-to-center holes distances (pitches) are built and tested using an impedance tube. The cases of closely separated holes are analyzed and compared to the cases of widely separated holes. It is observed that in the presen…
Propriétés acoustiques de matériaux poreux saturés d'air incluant une porosité partiellement ouverte
International audience; Nous étudions les propriétés d'un matériau à microgéométrie complexe incluant une porosité partiellement ouverte ou de culs-de-sacs. Ce type de matériau peut être obtenu par dissolution de grains de sel (NaCl) noyés dans une matrice de métal solidifié. Cette matrice est obtenue après invasion sous pression négative et à haute température des grains de sels par le métal sous forme liquide, puis refroidissement jusqu'à solidification du métal. La comparaison des résultats expérimentaux et théoriques sur le coefficient d'absorption acoustique d'une couche de ce métal poreux montre que le modèle de Biot-Johnson-Allard ne fournit pas des résultats aussi satisfaisants que …
Sound Propagation in Narrow Tubes with Periodically Spaced Lateral Cavities
International audience
Characterization of porous absorbent materials
International audience; Over the past twenty years, theoretical and experimental research on the acoustical properties of air-saturated porous materials for engineering applications has considerably progressed thanks to the contributions of many researchers in different institutes in the world. Accompanying the research on the acoustical properties of absorbent materials, new methods and experimental techniques were developed for the measurement of important physical parameters of these materials, necessary for the acoustic models. The attention is focused on the particularly important contributions of two laboratories: the Laboratoire dAcoustique de lUniversité du Maine (LAUM) in France …
Recent developments in the acoustical properties of perforated and porous materials containing dead-end pores
It was shown recently in Nevers, France, Sherbrooke, Canada and Salford, UK, that porous materials with semi-opened pores or materials with open pores bearing lateral cavities or resonators at the microscopic scale of the pores can result in peculiar sound absorption properties. Various examples of these materials can be found in engineering and in everyday life including bio-based materials. The cavities and resonators can be assimilated to dead-end pores, which are opened at one end and closed at the other. The dead-end pores are known to geophysicists. We studied them more recently in the field of engineering acoustics where the saturating fluid is air. The closed ends prevent the fluid …
High sound pressure model for cellular metallic foam with semi open cells
International audience
Transfer matrix modeling and numerical verification of locally reacting acoustic mosaics
International audience; This paper deals with the modeling of the acoustic behavior (absorption and transmission) of an acoustic mosaic having heterogeneous surface properties. On the surface, the material can be viewed as a collection of independent cells reacting locally. Each cell is filled with an absorbent material different from its neighbors. Such a mosaic may be seen as a generalization of the typical case of a honeycomb liner filled with absorbent materials. The originality of the study lies in the modeling of such heterogeneous material by an Admittance Sum Method (ASM) and a Transfer Matrix Method (TMM). The transfer matrix modeling of the heterogeneous material uses the summatio…
On the variations of acoustic absorption peak with particle velocity in micro-perforated panels at high level of excitation.
The acoustic behavior of micro-perforated panels (MPP) is studied theoretically and experimentally at high level of pressure excitation. A model based on Forcheimer's regime of flow velocity in the perforations is proposed. This model is valid at relatively high Reynolds numbers and low Mach numbers. The experimental method consists in measuring the acoustical pressure at three different positions in an impedance tube, the two measurement positions usually considered in an impedance tube and one measurement in the vicinity of the rear surface of the MPP. The impedance tube is equipped with a pressure driver instead of the usual loudspeaker and capable of delivering a high sound pressure lev…
Sound absorption coefficient of a porous material covered with a low open area perforated plate under high sound excitation
International audience; The sound absorption coefficient of porous materials covered with low open area perforated plate is studied under high sound intensities in the absence of mean flow. The theoretical considerations are based on the equivalent fluid following the Johnson-Champoux-Allard approach and the use of the transfer matrix method. To take into account the high sound levels effects, the air flow resistivity of each layer is modified following the Forchheimer law. Two specimens of perforated plate are built and tested when backed by a polymeric foam and a fibrous material. A specific impedance tube setup is developed for the measurement of the surface acoustic impedance for sound …
Holes Interaction Effects under high and medium Sound Intensities for Micro-perforated panels design
International audience; Most models for predicting the acoustic response of perforated panels are based on the assumption that there are no interactions between the holes. This paper investigates the Hole Interaction Effect (HIE) and distribution effect on the sound absorption coefficient of perforated panels when submitted to medium and high sound pressure levels. It is experimentally demonstrated that though the HIE is mostly an added mass effect, the nonlinear resistance parameters depend on the separation distance between the apertures. Analysis of the data reveals the fact that even with HIE, the nonlinear reactance dependency with velocity is very low compared to the resistance-veloci…
Caractérisation physique de matériaux poreux pour l'étude des interactions acoustique/structure
Cette thèse d'habilitation synthétise les dix ans de recherche qui suivirent ma thèse de doctorat dans les domaines des paramètres physiques et de l'acoustique des milieux poreux et des interactions fluide/squelette. Ce mémoire est divisé en trois parties principales A, B et C correspondant aux trois principales périodes de ma carrière scientifique: la période entre 1994 et 1997 passée au Laboratorium voor Akoestiek en Thermische Fysica de la K. U. Leuven en Belgique en collaboration avec le Laboratoire d'Acoustique de l'Université du Maine au Mans, la période entre 1997 et 2003 passée à Bradford (UK) en tant que chercheur (1997-2000) et les trois années passées à Hull (UK) en tant que maît…
Acoustic methods for measuring the porosities of porous materials incorporating dead-end pores
International audience; The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont et al. [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high …
Description of sound absorption by a flat resonator stacking metamaterial with double porosity model
Acoustic metamaterials can be designed by inserting along the path of a sound wave periodically spaced side resonators. An example of efficient design was recently proposed consisting of a perforated stacking of flat annular cavities (the pancake resonator), the perforation allowing the propagation of sound waves. The pancake resonator is used in absorber mode and the theoretical description of sound absorption can be achieved with the help of the theory of sound propagation in fluid saturated porous media in which two porosities are considered: the main porosity associated with the perforation and a porosity associated with the flat cavity volumes. Considering a perforation diameter and fl…
Development of a new Insulating bio-based composite made from sunflower stalk aggregates and chitosan: thermal, mechanical and acoustical characterizations
International audience
Acoustic properties of perforated plates and screens
International audience; In previous works, an acoustic model for Microperforated Insertion Unit (MIU), was developed to determine the input impedance of a system composed of a thin mesh (or screen) glued onto a perforated plate. An alternative approach is proposed by means of the equivalent fluid model of Johnson-Champoux-Allard involving five physical parameters: the tortuosity, the thermal and viscous characteristic lengths, the porosity and the flow resistivity. The input impedance of a multiple layer system can then be found by use of the transfer matrix method. Since the meshes have fairly simple structures, it was possible to model an elementary representative cell and to use calculat…