Littérature scientifique sur le sujet « Son – Absorption – Matériaux »
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Thèses sur le sujet "Son – Absorption – Matériaux"
GUIGNOUARD, PHILIPPE. « L'absorption acoustique des materiaux poreux predictions et mesures ». Le Mans, 1991. http://www.theses.fr/1991LEMA1018.
Texte intégralLafarge, Denis. « Propagation du son dans les matériaux poreux à structure rigide saturés par un fluide viscothermique : définition de paramètres géométriques, analogie électromagnétique, temps de relaxation ». Le Mans, 1993. http://cyberdoc.univ-lemans.fr/theses/1993/1993LEMA1009.pdf.
Texte intégralThe important role played by the characteristic lengths A, A' , is demonstrated by impedance measurements, for different materials such as reticulated polyurethane foams, and glass wool. There follows a discussion of the very definition of the geometrical parameters, the symmetry between viscous and thermal effects, and the viscous and thermal relaxation times. An electromagnetic analogy is used, in order to characterize the physical definition of the problem. A connection between the various degrees of approximation and the successive moments of the relaxation times distributions is demonstrated. As a result, the so-called "universality" appears as being nothing but the approximation of degree 0. Finally, departures from the universality theory are briefly investigated
Cérézo, Véronique. « Propriétés mécaniques, thermiques et acoustiques d'un matériau à base de particules végétales : approche expérimentale et modélisation théorique ». Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0037/these.pdf.
Texte intégralThis thesis deals with the measurement of physical properties (mechanical, thermal, acoustical) of various formulations of concrete containing vegetable particles. Such material is made up with hemp shives mixed with lime binders. Shives are very porous considering the ratio of capillaries. That fact explains that particles are lightweight, sensible to water and they can be highly strained. The ductile binder is a mixed between hydraulic and aerated lime with sometimes a volume of sand. Depending on the binder proportion, three microstructures of concrete are determined. Moreover, this material presents a microscopic porosity (shives) and a macroscopic porosity. These networks are connected. Vegetable concrete presents a ductile behavior. . The maximum stress and the Young modulus are limited as compare to other building materials but the bearable level of strain is rhigh. A theoretical model made with self-consistent method allows to calculate the Young modulus as a function of the mixture proportion and the compactness level. A comparison with experimental measurements shows a good accuracy of the results. Then, the dry thermal conductivity of vegetable concrete is studied. Considering its high sensibility to water, the level of sorption and the impact on thermal conductivity are evaluated. A self-consistent method leads to a model of dry and wet conductivity taking into account the physical properties (proportions, compactness) and the hygrometry. Lastly, the sound absorption of vegetable concrete is measured. The values are high. This first step in the study of the acoustical properties shows a behavior, which can be compared to materials with a double porosity
Gareton, Vincent. « Contribution à l'acoustique de conduits traités avec un matériau poreux : mesures de constantes élastiques et effets de la température ». Nantes, 2003. http://www.theses.fr/2003NANT2104.
Texte intégralOlny, Xavier. « Absorption acoustique des milieux poreux a simple et double porosité : modelisation et validation experimentale ». Lyon, INSA, 1999. http://www.theses.fr/1999ISAL0114.
Texte intégralPorous materials are widely used as passive absorbers in noisy buildings or outdoor environment. It appears useful to be able to describe and adapt the material to wanted performances. Acoustics of simple porosity media is recalled using an homogenisation technique of periodic separated scale media (HSP). The main phenomenological existing models are also presented. Then the HSP method, well adapted to double porosity media, is used to point out the diversity of interscale couplings in realistic media. The theory is compared to experimental measurements performed on artificial double porosity materials made of micro porous perforated panels. It is shown that the behaviour of multi-scale porous media can be significantly different from single porosity material. Two microporous media are used to build double porosity media corresponding to the cases of high and low permeability contrast. It appears that a second network of pores can greatly improved the absorption of the initial microporous material in a wide range of frequencies. Regarding the experimental set-up, the low frequency measurements have been performed in a large standing waves tube using an adaptation of the single microphone transfer function method. Also, Periodic sinusoidal pseudo-random test signals have been shown to improve the quality of the measurement regarding the distortion effects
REBILLARD, PASCAL. « Prediction de l'impedance de surface des materiaux poreux stratifies par la theorie de biot ». Le Mans, 1991. http://www.theses.fr/1991LEMA1006.
Texte intégralCastel, Franck. « Modélisation numérique de matériaux poreux hétérogènes : application à l'absorption basse fréquence ». Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0029/these.pdf.
Texte intégralThis PhD thesis deals with the numerical modelling of the low frequency absorption of porous heterogeneous materials. A quadratic finite element method based on Biot-Allard's theory and on an equivalent fluid formulation has been implemented and validated. An auto adaptative meshing procedure has been developed and validated in the case of the equivalent fluid formulation. An a posteriori error estimator was used to evaluate the interpolation errors using a finite difference like derivative of the pressure gradient at the mesh nodes. A criterion has been established in order to control the mesh refinement. The developed tool has been used for the modelling of double porosity materials (materials with a double scale of pores). The results obtained confirm Olny's analytical results. The distinctive peak found on the absorption spectra is well predicted. Its position can be determined analytically for periodic homogeneisable materials. The dissipated powers within the mesh elements are used to interpret the diffusion layer and the associated absorption peak. Moreover, an optimisation technique based on a surface response method is also proposed for double porosity materials. The developed tool is finally used for a parameters study of double layer materials with lateral leaks. It is shown that air leaks affect more the first layer. This effect increases with the layer thickness and flow resistance. This study shows in particular that it is possible to enhance the absorption of materials with air partitions. The developed tool is reliable and easy to use. However, the proposed auto adaptative meshing technique is limited to the equivalent fluid formulation
Lemarinier, Pavel. « Propagation du son dans des mousses et une laine de verre a structures rigides saturees par de l'air : validation experimentale de modeles thermiques, analogie dielectrique, impregnation polymere d'une mousse ». Le Mans, 1997. http://www.theses.fr/1997LEMA1004.
Texte intégralChedly, Slaheddine. « Compromis choc acoustique des matériaux poreux : relations procédé – produit - performances ». Reims, 2008. http://theses.univ-reims.fr/exl-doc/GED00000856.pdf.
Texte intégralIn car industry, security is an important subject in recent years and car manufacturers involve in the development of new technologies so that their products are more reliable for passengers. In the current context concerning both pedestrian shock and vehicles noise, materials selection offering good compromise between these aspects is an important concern of vehicle manufacturers. One possibility is the use of poroelastic materials stuck under engine cowling, which offer good energy dissipation upon impact, and good attenuation of acoustic waves emitted by the engine. For this, knowledge of Process - Product - Performances relationships is necessary. Modeling tools (Responses Surface Method, Kriging,…) are used to build empirical models expressing shock and acoustic performances of porous materials in order to quantify the relationship Process - Performances and Product - Performances. In this brief, the choice of inputs, outputs and experimental design type is crucial in the prospect of building meta-models. Genetic algorithms were effective tool when searching porous materials shock - acoustic compromise according to process conditions and intrinsic characteristics. The purpose of this work is searching ideal material offering good performances in shock absorption and acoustic isolation in the design area of design
Houdouin, Alexandre. « Vers une paroi acoustique absorbante en technologie MEMS ». Thesis, Le Mans, 2014. http://www.theses.fr/2014LEMA1020/document.
Texte intégralThe work presented in this thesis focuses on the development of a sound absorbent thin solution able to absorb sound waves of low frequency (500 - 1500 Hz). Noise is, actually, the primary source of environmental pollution raised by the public. This discomfort requires the establishment of acoustic solutions in order to improve the acoustic comfort. However, under certain conditions, the thickness of absorbent solutions strongly limit their use. Indeed, in general, more frequencies are low more the acoustic solutions used must be thick. The sound absorption noise of the solution presented in this work is based on a network of miniature electrodynamic transducers controlled from appropriate electrical loads connected to the terminals of the transducers. An analytical model of the behavior of sound absorbing wall was developed. This model takes into account the behavior of electrodynamic transducers used and the acoustic coupling between the various sources that are particularly important in the area of low frequencies. This model has been validated by two means : i) finite element modeling and ii) measuring the absorption of acoustic prototypes. Two types of absorbent walls were made. One is based on commercial micro-speakers, the other on a miniature MEMS transducer of similar dimensions but the conversion efficiency is an order of magnitude greater than conventional micro-speakers. Analytical modeling has shown two ways of improvements that have been undertaken, the first on the removal of short circuits present at the transducer, the second on optimizing the force factor for improving the conversion efficiency of electro-mechanics. The results sound absorption obtained from the MEMS transducers show that the solution has a real interest in the low frequency range where conventional solutions are not very effective