Erick Ogam - Academia.edu (original) (raw)

Papers by Erick Ogam

Research paper thumbnail of Acoustic wave propagation in fractal porous material

Research paper thumbnail of Application of the Biot model to ultrasound in bone: Inverse problem

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Jul 1, 2008

This paper concerns the ultrasonic characterization of human cancellous bone samples by solving t... more This paper concerns the ultrasonic characterization of human cancellous bone samples by solving the inverse problem using experimentally measured signals. The inverse problem is solved numerically by the least squares method. Five parameters are inverted: porosity, tortuosity, viscous characteristic length, Young modulus, and Poisson ratio of the skeletal frame. The minimization of the discrepancy between experiment and theory is made in the time domain. The ultrasonic propagation in cancellous bone is modelled using the Biot theory modified by the Johnson-Koplik-Dashen model for viscous exchange between fluid and structure. The sensitivity of the Young modulus and the Poisson ratio of the skeletal frame is studied showing their effect on the fast and slow waveforms. The inverse problem is shown to be well posed, and its solution to be unique. Experimental results for slow and fast waves transmitted through human cancellous bone samples are given and compared with theoretical predictions.

Research paper thumbnail of Transient Propagation of Longitudinal and Transverse Waves in Cancellous Bone: Application of Biot Theory and Fractional Calculus

Symmetry, Sep 21, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Synthesis and Mechanical Characterization of Binary and Ternary Intermetallic Alloys Based on Fe-Ti-Al by Resonant Ultrasound Vibrational Methods

Materials, May 7, 2018

Precise but simple experimental and inverse methods allowing the recovery of mechanical material ... more Precise but simple experimental and inverse methods allowing the recovery of mechanical material parameters are necessary for the exploration of materials with novel crystallographic structures and elastic properties, particularly for new materials and those existing only in theory. The alloys studied herein are of new atomic compositions. This paper reports an experimental study involving the synthesis and development of methods for the determination of the elastic properties of binary (Fe-Al, Fe-Ti and Ti-Al) and ternary (Fe-Ti-Al) intermetallic alloys with different concentrations of their individual constituents. The alloys studied were synthesized from high purity metals using an arc furnace with argon flow to ensure their uniformity and homogeneity. Precise but simple methods for the recovery of the elastic constants of the isotropic metals from resonant ultrasound vibration data were developed. These methods allowed the fine analysis of the relationships between the atomic concentration of a given constituent and the Young's modulus or alloy density.

Research paper thumbnail of Extension of propagation models in porous materials to higher orders

HAL (Le Centre pour la Communication Scientifique Directe), Apr 11, 2022

Research paper thumbnail of Application of fractional calculus to the ultrasonic characterization of human bone tissue

Journal of the Acoustical Society of America, Oct 1, 2020

Transient ultrasonic propagation in human bone tissue is considered according to Biot's theory. T... more Transient ultrasonic propagation in human bone tissue is considered according to Biot's theory. The bone is modeled as a porous medium with an elastic structure. The viscous uid/structure interactions are described by fractional calculus in the time domain. The slow and fast compressional waves, as well as the rotational shear wave predicted by Biot's theory obey fractional propagation equations. The fractional equation system is solved analytically in the time domain, thus obtaining the expressions of the reection and transmission scattering operators. Inverse identication of the intrinsic microstructure of the pores and of the mechanical properties of the bone is performed in the time domain (waveforms) and frequency domain (attenuation and phase velocities), by adopting a statistical Bayesian inference technique using ultrasonic transmitted and reected signals, which allows to nd the identied parameters and their associated uncertainty.

Research paper thumbnail of Inverse identification of a higher order viscous parameter of rigid porous media in the high frequency domain

Journal of the Acoustical Society of America, Mar 1, 2019

In this paper, a modeling extension for the description of wave propagation in rigid porous media... more In this paper, a modeling extension for the description of wave propagation in rigid porous media at high frequencies is used. To better characterize the visco-inertial and thermal interactions between the fluid and the structure in this regime, two additional characteristic viscous and thermal surfaces Σ and Σ are taken into account, as initially introduced in [J. Kergomardet al., Acta Acust united Ac 99 (4) (2013) 557-571]. This extends the modeling order of the dynamic tortuosity and compressibility. A sensitivity analysis is performed on the additional parameters, showing that only the viscous surface Σ has an influence on transmitted waves in the high frequency regime, for materials having a low viscous characteristic length. A general Bayesian inference is then conducted to infer simultaneously the posterior probability densities of the parameters associated with the visco-inertial effects, i.e., the porosity, tortuosity, the viscous characteristic length, and the viscous characteristic surface. The proposed method is based on the measurement of waves transmitted by a slab of rigid porous material in the time domain. Bayesian inference results obtained on three different porous materials are presented.

Research paper thumbnail of Temperature-Dependent Elastic Constants of Substrates for Manufacture of Mems Devices

HAL (Le Centre pour la Communication Scientifique Directe), Apr 25, 2022

We present a comparative computational study of temperature-dependent elastic constants of silico... more We present a comparative computational study of temperature-dependent elastic constants of silicon (Si), silicon carbide (SiC) and diamond as substrates that are commonly used in the manufacture of Micro-Electromechanical Systems (MEMS) devices. Also mentioned is Cd 2 SnO 4 , whose ground-state elastic constants were determined just recently for the first time. Si is the dominant substrate used in the manufacture of MEMS devices, owing to its desirable electrical, electronic, thermal and mechanical properties. However, its low hardness, brittleness and inability to work under harsh environment such as hightemperature environment, has limited its use in the manufacture of MEMS like mechanical sensors and bioMEMS. Mechanical sensors are fabricated on SiC and diamond due to their high Young's moduli as well as high fracture strength, while the bioMEMS are fabricated on polymers. The effect of temperature on the elastic constants of these substrates will help in giving insight into how their performance vary with temperature.

Research paper thumbnail of Acoustical properties of compressed earth blocks: Effect of compaction pressure, water hyacinth ash and lime

Case Studies in Construction Materials

Research paper thumbnail of A Generalization of Poiseuille’s Law for the Flow of a Self-Similar (Fractal) Fluid through a Tube Having a Fractal Rough Surface

Fractal and Fractional

In this paper, a generalization of Poiseuille’s law for a self-similar fluid flow through a tube ... more In this paper, a generalization of Poiseuille’s law for a self-similar fluid flow through a tube having a rough surface is proposed. The originality of this work is to consider, simultaneously, the self-similarity structure of the fluid and the roughness of the tube surface. This study can have a wide range of applications, for example, for fractal fluid dynamics in hydrology. The roughness of the tube surface presents a fractal structure that can be described by the surface fractal noninteger dimensions. Complex fluids that are invariant to changes in scale (self-similar) are modeled as a continuous medium in noninteger dimensional spaces. In this work, the analytical solution of the Navier–Stokes equations for the case of a self-similar fluid flow through a rough “fractal” tube is presented. New expressions of the velocity profiles, the fluid discharge, and the friction factor are determined analytically and plotted numerically. These expressions contain fractal dimensions describ...

Research paper thumbnail of Propagation acoustique dans un milieu poreux : effet de l'onde de cisaillement

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Research paper thumbnail of Flow of a Self-Similar Non-Newtonian Fluid Using Fractal Dimensions

Fractal and Fractional

In this paper, the study of the fully developed flow of a self-similar (fractal) power-law fluid ... more In this paper, the study of the fully developed flow of a self-similar (fractal) power-law fluid is presented. The rheological way of behaving of the fluid is modeled utilizing the Ostwald–de Waele relationship (covering shear-thinning, Newtonian and shear-thickening fluids). A self-similar (fractal) fluid is depicted as a continuum in a noninteger dimensional space. Involving vector calculus for the instance of a noninteger dimensional space, we determine an analytical solution of the Cauchy equation for the instance of a non-Newtonian self-similar fluid flow in a cylindrical pipe. The plot of the velocity profile obtained shows that the rheological behavior of a non-Newtonian power-law fluid is essentially impacted by its self-similar structure. A self-similar shear thinning fluid and a self-similar Newtonian fluid take on a shear-thickening way of behaving, and a self-similar shear-thickening fluid becomes more shear thickening. This approach has many useful applications in indus...

Research paper thumbnail of Reflection and transmission of transient ultrasonic wave in fractal porous material: Application of fractional calculus

Wave Motion

This paper provides a time domain model for the propagation of transient ultrasonic waves in a se... more This paper provides a time domain model for the propagation of transient ultrasonic waves in a self-similar porous material having a rigid frame. This model is based on the formalism of Stillinger-Palmer-Stavrinou, which consists in modeling the fractal material as a porous medium with a non-integer dimensional space. This paper is devoted to the time-domain analytical calculus of the reection and transmission operators that are expressed in terms of Mittag-Leer functions. A sensitivity numerical study using ultrasonic reected and transmitted waves is performed, highlighting the eect of of the material's physical parameters (fractal dimension, tortuosity, viscous characteristic length and porosity) on the waveforms.

Research paper thumbnail of Accurate Ab-initio calculation of elastic constants of anisotropic binary alloys: A case of Fe–Al

Solid State Communications

Research paper thumbnail of Structural and Mechanical Properties of theTi32Al68 and Ti40Al60 Binary Alloys: Experimental and computational Studies

Research paper thumbnail of Probing flexible thermoplastic thin films on a substrate using ultrasonic waves to retrieve mechanical moduli and density: Inverse problem

Journal of Physics: Conference Series, 2018

International audienc

Research paper thumbnail of Le problème inverse de diffraction des ondes acoustiques audibles par un cylindre poroélastique saturé d'air

HAL (Le Centre pour la Communication Scientifique Directe), Apr 22, 2014

International audienceL'utilisation efficace des mousses plastiques dans un large éventail d&... more International audienceL'utilisation efficace des mousses plastiques dans un large éventail d'applications structurelles comme le contrôle sonore passif ou le soutien anatomique dans les matelas de couchage et les fauteuils rembourrés, nécessite une caractérisation détaillée de leur perméabilité et de leurs caractéristiques de déformation. Les modules élastiques et la résistivité au passage de l'air des mousses sont souvent mesurées en utilisant deux techniques distinctes, l'une employant des méthodes de vibrations mécaniques et l'autre le taux d'écoulement de fluides (p. ex. flux d'air) basé sur la technologie de la mécanique des fluides. Un modèle d'interactions entre le fluide saturant et la structure basé sur la théorie de Biot modifiée et la décomposition de l'onde plane en fonctions cylindriques orthogonales est utilisé pour résoudre le problème inverse. Les solutions de l'inversion sont obtenues par la construction d'une fonction objectif qui exprime la différence entre les données calculées et les données acoustiques acquises dans une chambre anéchoïque.Une méthode de résolution du problème inverse multi-paramètre pour récupérer la résistivité au passage d'air (RPA) et les propriétés mécaniques classiques pour le squelette d'un cylindre en mousse poreux, saturé par l'air à partir des ondes diffractées, est développée. La valeur de l'RPA récupérée est en bon accord avec celle obtenue en basses fréquences pour un échantillon de mousse découpée dans le cylindre et caractérisé en utilisant un procédé mettant en uvre, les ondes transmises et réfléchies dans un guide d'onde d'une grande longueur, mis au point précédemment par Fellah et al. [Rev Sci . Instrum . 78 ( 11 ) , 114902 (2007 ). Une étude de sensibilité sur l'influence du coefficient de Poisson sur le champ rétro-diffusé montre que l'interaction entre le fluide saturant et la structure (squelette) du matériau cellulaire doit être prise en considération

Research paper thumbnail of Recovery of the ARMA Model parameters from the vibration response of a finite lenght elastic cylinder using neural networks

Research paper thumbnail of Propagation of acoustic waves in micro-polar porous medium

Generally, in acoustic propagation in porous media such as rocks or bone tissues, classical elast... more Generally, in acoustic propagation in porous media such as rocks or bone tissues, classical elasticity is used, in which the stresses are proportional to the deformations and only the translation aspect is taken into account. However, it has been shown that in these porous media, the rotational movement of particles (solid or fluid) between them (gyration) is not negligible, and this is described by micro-polar theories. In this work, the acoustic wave propagation in micro-polar porous material in the high frequency range is studied. The fluid / structure and micro-polar couplings are well described in the Biot equations. The motion equations are solved in the frequency domain, thus obtaining the dispersion relations. Several propagation modes are highlighted, in addition to the two classical Biot waves and the shear wave, a micro-polar compression wave and a micro-polar shear wave are obtained. The phase velocities of these five waves are calculated and plotted against frequency. A...

Research paper thumbnail of Wave Propagation in Porous Materials

This chapter provides different models for the acoustic wave propagation in porous materials havi... more This chapter provides different models for the acoustic wave propagation in porous materials having a rigid and an elastic frames. The direct problem of reflection and transmission of acoustic waves by a slab of porous material is studied. The inverse problem is solved using experimental reflected and transmitted signals. Both highand low-frequency domains are studied. Different acoustic methods are proposed for measuring physical parameters describing the acoustic propagation as porosity, tortuosity, viscous and thermal characteristic length, and flow resistivity. Some advantages and perspectives of this method are discussed.

Research paper thumbnail of Acoustic wave propagation in fractal porous material

Research paper thumbnail of Application of the Biot model to ultrasound in bone: Inverse problem

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Jul 1, 2008

This paper concerns the ultrasonic characterization of human cancellous bone samples by solving t... more This paper concerns the ultrasonic characterization of human cancellous bone samples by solving the inverse problem using experimentally measured signals. The inverse problem is solved numerically by the least squares method. Five parameters are inverted: porosity, tortuosity, viscous characteristic length, Young modulus, and Poisson ratio of the skeletal frame. The minimization of the discrepancy between experiment and theory is made in the time domain. The ultrasonic propagation in cancellous bone is modelled using the Biot theory modified by the Johnson-Koplik-Dashen model for viscous exchange between fluid and structure. The sensitivity of the Young modulus and the Poisson ratio of the skeletal frame is studied showing their effect on the fast and slow waveforms. The inverse problem is shown to be well posed, and its solution to be unique. Experimental results for slow and fast waves transmitted through human cancellous bone samples are given and compared with theoretical predictions.

Research paper thumbnail of Transient Propagation of Longitudinal and Transverse Waves in Cancellous Bone: Application of Biot Theory and Fractional Calculus

Symmetry, Sep 21, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Synthesis and Mechanical Characterization of Binary and Ternary Intermetallic Alloys Based on Fe-Ti-Al by Resonant Ultrasound Vibrational Methods

Materials, May 7, 2018

Precise but simple experimental and inverse methods allowing the recovery of mechanical material ... more Precise but simple experimental and inverse methods allowing the recovery of mechanical material parameters are necessary for the exploration of materials with novel crystallographic structures and elastic properties, particularly for new materials and those existing only in theory. The alloys studied herein are of new atomic compositions. This paper reports an experimental study involving the synthesis and development of methods for the determination of the elastic properties of binary (Fe-Al, Fe-Ti and Ti-Al) and ternary (Fe-Ti-Al) intermetallic alloys with different concentrations of their individual constituents. The alloys studied were synthesized from high purity metals using an arc furnace with argon flow to ensure their uniformity and homogeneity. Precise but simple methods for the recovery of the elastic constants of the isotropic metals from resonant ultrasound vibration data were developed. These methods allowed the fine analysis of the relationships between the atomic concentration of a given constituent and the Young's modulus or alloy density.

Research paper thumbnail of Extension of propagation models in porous materials to higher orders

HAL (Le Centre pour la Communication Scientifique Directe), Apr 11, 2022

Research paper thumbnail of Application of fractional calculus to the ultrasonic characterization of human bone tissue

Journal of the Acoustical Society of America, Oct 1, 2020

Transient ultrasonic propagation in human bone tissue is considered according to Biot's theory. T... more Transient ultrasonic propagation in human bone tissue is considered according to Biot's theory. The bone is modeled as a porous medium with an elastic structure. The viscous uid/structure interactions are described by fractional calculus in the time domain. The slow and fast compressional waves, as well as the rotational shear wave predicted by Biot's theory obey fractional propagation equations. The fractional equation system is solved analytically in the time domain, thus obtaining the expressions of the reection and transmission scattering operators. Inverse identication of the intrinsic microstructure of the pores and of the mechanical properties of the bone is performed in the time domain (waveforms) and frequency domain (attenuation and phase velocities), by adopting a statistical Bayesian inference technique using ultrasonic transmitted and reected signals, which allows to nd the identied parameters and their associated uncertainty.

Research paper thumbnail of Inverse identification of a higher order viscous parameter of rigid porous media in the high frequency domain

Journal of the Acoustical Society of America, Mar 1, 2019

In this paper, a modeling extension for the description of wave propagation in rigid porous media... more In this paper, a modeling extension for the description of wave propagation in rigid porous media at high frequencies is used. To better characterize the visco-inertial and thermal interactions between the fluid and the structure in this regime, two additional characteristic viscous and thermal surfaces Σ and Σ are taken into account, as initially introduced in [J. Kergomardet al., Acta Acust united Ac 99 (4) (2013) 557-571]. This extends the modeling order of the dynamic tortuosity and compressibility. A sensitivity analysis is performed on the additional parameters, showing that only the viscous surface Σ has an influence on transmitted waves in the high frequency regime, for materials having a low viscous characteristic length. A general Bayesian inference is then conducted to infer simultaneously the posterior probability densities of the parameters associated with the visco-inertial effects, i.e., the porosity, tortuosity, the viscous characteristic length, and the viscous characteristic surface. The proposed method is based on the measurement of waves transmitted by a slab of rigid porous material in the time domain. Bayesian inference results obtained on three different porous materials are presented.

Research paper thumbnail of Temperature-Dependent Elastic Constants of Substrates for Manufacture of Mems Devices

HAL (Le Centre pour la Communication Scientifique Directe), Apr 25, 2022

We present a comparative computational study of temperature-dependent elastic constants of silico... more We present a comparative computational study of temperature-dependent elastic constants of silicon (Si), silicon carbide (SiC) and diamond as substrates that are commonly used in the manufacture of Micro-Electromechanical Systems (MEMS) devices. Also mentioned is Cd 2 SnO 4 , whose ground-state elastic constants were determined just recently for the first time. Si is the dominant substrate used in the manufacture of MEMS devices, owing to its desirable electrical, electronic, thermal and mechanical properties. However, its low hardness, brittleness and inability to work under harsh environment such as hightemperature environment, has limited its use in the manufacture of MEMS like mechanical sensors and bioMEMS. Mechanical sensors are fabricated on SiC and diamond due to their high Young's moduli as well as high fracture strength, while the bioMEMS are fabricated on polymers. The effect of temperature on the elastic constants of these substrates will help in giving insight into how their performance vary with temperature.

Research paper thumbnail of Acoustical properties of compressed earth blocks: Effect of compaction pressure, water hyacinth ash and lime

Case Studies in Construction Materials

Research paper thumbnail of A Generalization of Poiseuille’s Law for the Flow of a Self-Similar (Fractal) Fluid through a Tube Having a Fractal Rough Surface

Fractal and Fractional

In this paper, a generalization of Poiseuille’s law for a self-similar fluid flow through a tube ... more In this paper, a generalization of Poiseuille’s law for a self-similar fluid flow through a tube having a rough surface is proposed. The originality of this work is to consider, simultaneously, the self-similarity structure of the fluid and the roughness of the tube surface. This study can have a wide range of applications, for example, for fractal fluid dynamics in hydrology. The roughness of the tube surface presents a fractal structure that can be described by the surface fractal noninteger dimensions. Complex fluids that are invariant to changes in scale (self-similar) are modeled as a continuous medium in noninteger dimensional spaces. In this work, the analytical solution of the Navier–Stokes equations for the case of a self-similar fluid flow through a rough “fractal” tube is presented. New expressions of the velocity profiles, the fluid discharge, and the friction factor are determined analytically and plotted numerically. These expressions contain fractal dimensions describ...

Research paper thumbnail of Propagation acoustique dans un milieu poreux : effet de l'onde de cisaillement

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Research paper thumbnail of Flow of a Self-Similar Non-Newtonian Fluid Using Fractal Dimensions

Fractal and Fractional

In this paper, the study of the fully developed flow of a self-similar (fractal) power-law fluid ... more In this paper, the study of the fully developed flow of a self-similar (fractal) power-law fluid is presented. The rheological way of behaving of the fluid is modeled utilizing the Ostwald–de Waele relationship (covering shear-thinning, Newtonian and shear-thickening fluids). A self-similar (fractal) fluid is depicted as a continuum in a noninteger dimensional space. Involving vector calculus for the instance of a noninteger dimensional space, we determine an analytical solution of the Cauchy equation for the instance of a non-Newtonian self-similar fluid flow in a cylindrical pipe. The plot of the velocity profile obtained shows that the rheological behavior of a non-Newtonian power-law fluid is essentially impacted by its self-similar structure. A self-similar shear thinning fluid and a self-similar Newtonian fluid take on a shear-thickening way of behaving, and a self-similar shear-thickening fluid becomes more shear thickening. This approach has many useful applications in indus...

Research paper thumbnail of Reflection and transmission of transient ultrasonic wave in fractal porous material: Application of fractional calculus

Wave Motion

This paper provides a time domain model for the propagation of transient ultrasonic waves in a se... more This paper provides a time domain model for the propagation of transient ultrasonic waves in a self-similar porous material having a rigid frame. This model is based on the formalism of Stillinger-Palmer-Stavrinou, which consists in modeling the fractal material as a porous medium with a non-integer dimensional space. This paper is devoted to the time-domain analytical calculus of the reection and transmission operators that are expressed in terms of Mittag-Leer functions. A sensitivity numerical study using ultrasonic reected and transmitted waves is performed, highlighting the eect of of the material's physical parameters (fractal dimension, tortuosity, viscous characteristic length and porosity) on the waveforms.

Research paper thumbnail of Accurate Ab-initio calculation of elastic constants of anisotropic binary alloys: A case of Fe–Al

Solid State Communications

Research paper thumbnail of Structural and Mechanical Properties of theTi32Al68 and Ti40Al60 Binary Alloys: Experimental and computational Studies

Research paper thumbnail of Probing flexible thermoplastic thin films on a substrate using ultrasonic waves to retrieve mechanical moduli and density: Inverse problem

Journal of Physics: Conference Series, 2018

International audienc

Research paper thumbnail of Le problème inverse de diffraction des ondes acoustiques audibles par un cylindre poroélastique saturé d'air

HAL (Le Centre pour la Communication Scientifique Directe), Apr 22, 2014

International audienceL'utilisation efficace des mousses plastiques dans un large éventail d&... more International audienceL'utilisation efficace des mousses plastiques dans un large éventail d'applications structurelles comme le contrôle sonore passif ou le soutien anatomique dans les matelas de couchage et les fauteuils rembourrés, nécessite une caractérisation détaillée de leur perméabilité et de leurs caractéristiques de déformation. Les modules élastiques et la résistivité au passage de l'air des mousses sont souvent mesurées en utilisant deux techniques distinctes, l'une employant des méthodes de vibrations mécaniques et l'autre le taux d'écoulement de fluides (p. ex. flux d'air) basé sur la technologie de la mécanique des fluides. Un modèle d'interactions entre le fluide saturant et la structure basé sur la théorie de Biot modifiée et la décomposition de l'onde plane en fonctions cylindriques orthogonales est utilisé pour résoudre le problème inverse. Les solutions de l'inversion sont obtenues par la construction d'une fonction objectif qui exprime la différence entre les données calculées et les données acoustiques acquises dans une chambre anéchoïque.Une méthode de résolution du problème inverse multi-paramètre pour récupérer la résistivité au passage d'air (RPA) et les propriétés mécaniques classiques pour le squelette d'un cylindre en mousse poreux, saturé par l'air à partir des ondes diffractées, est développée. La valeur de l'RPA récupérée est en bon accord avec celle obtenue en basses fréquences pour un échantillon de mousse découpée dans le cylindre et caractérisé en utilisant un procédé mettant en uvre, les ondes transmises et réfléchies dans un guide d'onde d'une grande longueur, mis au point précédemment par Fellah et al. [Rev Sci . Instrum . 78 ( 11 ) , 114902 (2007 ). Une étude de sensibilité sur l'influence du coefficient de Poisson sur le champ rétro-diffusé montre que l'interaction entre le fluide saturant et la structure (squelette) du matériau cellulaire doit être prise en considération

Research paper thumbnail of Recovery of the ARMA Model parameters from the vibration response of a finite lenght elastic cylinder using neural networks

Research paper thumbnail of Propagation of acoustic waves in micro-polar porous medium

Generally, in acoustic propagation in porous media such as rocks or bone tissues, classical elast... more Generally, in acoustic propagation in porous media such as rocks or bone tissues, classical elasticity is used, in which the stresses are proportional to the deformations and only the translation aspect is taken into account. However, it has been shown that in these porous media, the rotational movement of particles (solid or fluid) between them (gyration) is not negligible, and this is described by micro-polar theories. In this work, the acoustic wave propagation in micro-polar porous material in the high frequency range is studied. The fluid / structure and micro-polar couplings are well described in the Biot equations. The motion equations are solved in the frequency domain, thus obtaining the dispersion relations. Several propagation modes are highlighted, in addition to the two classical Biot waves and the shear wave, a micro-polar compression wave and a micro-polar shear wave are obtained. The phase velocities of these five waves are calculated and plotted against frequency. A...

Research paper thumbnail of Wave Propagation in Porous Materials

This chapter provides different models for the acoustic wave propagation in porous materials havi... more This chapter provides different models for the acoustic wave propagation in porous materials having a rigid and an elastic frames. The direct problem of reflection and transmission of acoustic waves by a slab of porous material is studied. The inverse problem is solved using experimental reflected and transmitted signals. Both highand low-frequency domains are studied. Different acoustic methods are proposed for measuring physical parameters describing the acoustic propagation as porosity, tortuosity, viscous and thermal characteristic length, and flow resistivity. Some advantages and perspectives of this method are discussed.