0000000000283074
AUTHOR
Raymond Panneton
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…
Acoustics of porous materials with partially opened porosity
International audience; A theoretical and experimental study of the acoustic properties of porous materials containing dead-end (or partially opened) porosity was recently proposed by Dupont et al. The present article provides a description of partially opened porosity systems and their numerous potential applications in the general context of the study of porous materials, the classical models describing them, and the characterization techniques. It is shown that the dead-end pore effect can be treated independently and that the description of this effect can be associated with any acoustic model of porous media. Different theoretical developments describing the dead-end porosity effect ar…
Sound Propagation in Narrow Tubes with Periodically Spaced Lateral Cavities
International audience
Acoustical properties of air-saturated porous material with periodically distributed dead-end pores
International audience; A theoretical and numerical study of the sound propagation in air-saturated porous media with straight main pores bearing lateral cavities (dead-ends) is presented. The lateral cavities are located at " nodes " periodically spaced along each main pore. The effect of periodicity in the distribution of the lateral cavities is studied, and the low frequency limit valid for the closely spaced dead-ends is considered separately. It is shown that the absorption coefficient and transmission loss are influenced by the viscous and thermal losses in the main pores as well as their perforation rate. The presence of long or short dead-ends significantly alters the acoustical pro…
Impact Test and Mixture Approach to the Study of the Acoustic Properties of Rigid Frame Porous Materials with Functionally Graded Macroscopic Physical Parameters
International audience
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 …
Propriétés acoustiques de matériaux perforés comprenant des pores dead-end périodiques pour des applications basses fréquences
International audience; Pour un matériau absorbant tel que la mélamine et pour une épaisseur assez faible (inférieure à 5 cm), l'absorption acoustique devient supérieure à 0.8 à partir d'une fréquence de l'ordre de 1000 Hz. Une étude récente [1] a montré que des matériaux perforés peu épais comportant le long des perforations des pores dead-ends (DE) régulièrement espacés peuvent permettre de produire des pics d'absorption supérieurs à 0.8 en basses fréquences (quelques centaines de Hz). Les dimensions des pores DE ainsi que leur périodicité peuvent être millimétrique ou submillimétrique de sorte que l'épaisseur totale du matériau soit de seulement quelques centimètres. Ces pores DE peuvent…
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…
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 …
Transfer matrix method applied to the parallel assembly of sound absorbing materials
International audience; The transfer matrix method (TMM) is used conventionally to predict the acoustic properties of laterally infinite homogeneous layers assembled in series to form a multilayer. In this work, a parallel assembly process of transfer matrices is used to model heterogeneous materials such as patchworks, acoustic mosaics, or a collection of acoustic elements in parallel. In this method, it is assumed that each parallel element can be modeled by a 2 × 2 transfer matrix, and no diffusion exists between elements. The resulting transfer matrix of the parallel assembly is also a 2 × 2 matrix that can be assembled in series with the classical TMM. The method is validated by compar…