Stéphane Job

Stéphane Job
Supméca - Institut supérieur de mécanique de Paris · Laboratoire Quartz

PhD in Acoustics

About

44
Publications
3,738
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1,221
Citations

Publications

Publications (44)
Preprint
Full-text available
Energy absorbers and energy-harvesting devices have been under the scope of scientists and engineers for decades to fulfill specific technological needs, mainly concerned with sound and vibration absorbers, and efficient mechanical energy converters. In this paper, as a proof of concept, we build a mass-in-mass device to study the response of a lin...
Article
Full-text available
Energy absorbers and energy-harvesting devices have been under the scope of scientists and engineers for decades to fulfill specific technological needs, mainly concerned with sound and vibration absorbers, and efficient mechanical energy converters. In this paper, as a proof of concept, we build a mass-in-mass device to study the response of a lin...
Article
Full-text available
This paper reassesses carefully the effects and consequences of instantaneous contact mechanics versus finite contact duration modeling of Vibro-Impact Nonlinear Energy Sinks (VI NES). The device is composed of a container enclosing an inelastic sphere, interacting via a nonlinear viscoelastic dissipative force with the inner walls of the container...
Article
Full-text available
Energy absorbers and energy-harvesting devices have been under the scope of scientists and engineers for decades to fulfill specific technological needs, mainly concerned with sound and vibration absorbers, and efficient mechanical energy converters. In this paper, as a proof of concept, we build a mass-in-mass device to study the response of a lin...
Article
Full-text available
We study, via discrete element method simulations, the apparent mass (m, the ratio of a driving force to a resulting acceleration) and loss factor (η\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemarg...
Article
The contact stiffness between a poro-elastic spherical grain, made out of an open-cell foam, and a plane is studied with the aim of determining the contact law, and in particular verifying if the Hertz interaction potential, originally derived in the frame of continuum mechanics, holds. The contact law is studied experimentally by compressing a hal...
Preprint
Full-text available
We study, via DEM simulations, the apparent mass $m$ and loss factor $\eta$ of particle dampers (PD) attached to a vertically driven, single degree of freedom mechanical system. Although many studies focus on $\eta$, less work has been devoted to $m$. It has been recently demonstrated [M. Masmoudi \textit{et al}. Granular Matter 18 (2016) 71.] that...
Article
Full-text available
The propagation of mechanical energy in granular materials has been intensively studied in recent years given the wide range of fields that have processes related to this phenomena, from geology to impact mitigation and protection of buildings and structures. In this paper, we experimentally explore the effect of an interstitial fluid on the dynami...
Poster
Full-text available
A vibrated granular medium can adopt different behaviors depending on the control parameter $\Gamma=A\omega^2/g$, where $A$ is the amplitude, $\omega$ is the vibration frequency, and $g$ is the acceleration of gravity. For different values of \Gamma, the system behaves like a solid or fluid or even both states can coexist. In this work, we will sh...
Preprint
Full-text available
The propagation of mechanical energy in granular materials has been intensively studied in recent years given the wide range of fields that have processes related to this phenomena, from geology to impact mitigation and protection of buildings and structures. In this article, we experimentally explore the effect of an interstitial viscous fluid on...
Conference Paper
Particle damping is an emerging technology among passive devices for furnishing high damping of structural vibration, particularly in harsh environment, through the use of granular particles filled within an enclosure. In this work, we investigate experimentally the effect of acceleration amplitude, mass ratio, volume package, and type of material...
Article
Full-text available
Dense colloidal suspensions can propagate and absorb large mechanical stresses, including impacts and shocks. The wave transport stems from the delicate interplay between the spatial arrangement of the structural units and solvent-mediated effects. For dynamic microscopic systems, elastic deformations of the colloids are usually disregarded due to...
Article
In inhomogeneous media with constituents having very different acoustic properties, very strong multiple scattering of ultrasonic waves can occur, especially when the wavelength is comparable with the length scales over which the constituent properties vary. Such strong multiple scattering can lead to a long “coda” that dominates the observable beh...
Article
A theoretical and experimental study of the acoustic absorption of granular porous media made of non-cohesive piles of spherical shells is presented. These shells are either rigid or elastic, possibly drilled with a neck (Helmholtz resonators), and either porous or impervious. A description is given of acoustic propagation through these media using...
Article
Full-text available
L'absorption des ondes acoustiques en basses fréquences, quand la longueur d’onde est très grande devant l’épaisseur du traitement, reste un challenge. Cette étude illustre les performances d’une nouvelle catégorie de matériaux poro-granulaires, composés de coques sphériques creuses. Les coques peuvent être rigides ou élastiques, percées ou munies...
Article
Full-text available
Particle dampers are passive devices allowing strong damping of structures vibrating in harsh environment. We investigate the energy dissipation in a rigid enclosure attached to a shaker and partially filled with particles. Our experiments match an analytical description, which we corroborate then with discrete element method simulations. We show t...
Chapter
We present preliminary results devoted to study and analyze the main features of particle damping from numerical simulations and experimental procedures. Particle damping is measured for free-free beam with particle filled enclosure attached to their both sides. Particle damping is measured for different amplitude vibration and the goal is to highl...
Article
Full-text available
We study experimentally the interaction between two solitary waves that approach one another in a linear chain of spheres interacting via the Hertz potential. When these counterpropagating waves collide, they cross each other and a phase shift in respect to the noninteracting waves is introduced as a result of the nonlinear interaction potential. T...
Article
Full-text available
We present a systematic study of the existence and stability of discrete breathers that are spatially localized in the bulk of a one-dimensional chain of compressed elastic beads that interact via Hertzian contact. The chain is diatomic, consisting of a periodic arrangement of heavy and light spherical particles. We examine two families of discrete...
Article
Full-text available
We report the experimental observation of discrete breathers in a one-dimensional diatomic granular crystal composed of compressed elastic beads that interact via Hertzian contact. We first characterize their effective linear spectrum both theoretically and experimentally. We then illustrate theoretically and numerically the modulational instabilit...
Article
Full-text available
We investigate the dynamical response of a mass defect in a one-dimensional non-loaded horizontal chain of identical spheres which interact via the nonlinear Hertz potential. Our experiments show that the interaction of a solitary wave with a light intruder excites localized mode. In agreement with dimensional analysis, we find that the frequency o...
Article
A one-dimensional dry granular medium, a chain of beads which interact via the nonlinear Hertz potential, exhibits strongly nonlinear behaviors. When such an alignment contains some viscous fluid between grains, it exhibits new interesting features. We report some recent experiments, analysis and numerical simulations concerning nonlinear wave prop...
Article
A one-dimensional dry granular medium, a chain of beads which interact via the nonlinear Hertz potential, exhibits strongly nonlinear behaviors. When such an alignment further contains some fluid in the interstices between grains, it may exhibit new interesting features. We report some recent experiments, analysis and numerical simulations concerni...
Article
Full-text available
The features of solitary waves observed in horizontal monodisperse chain of barely touching beads not only depend on geometrical and material properties of the beads but also on the initial perturbation provided at the edge of the chain. An impact of a large striker on a monodisperse chain, and similarly a sharp decrease of bead radius in a stepped...
Article
Full-text available
A one-dimensional granular medium, a chain of beads which interact via the nonlinear Hertz potential, exhibits strongly nonlinear behaviors. When an alignment of grains further contains some heterogeneities (e.g. local modification of the inertia or of the stiffness), it exhibits even more complex behaviors. We report some recent experiments, analy...
Article
Full-text available
We present an experimental study of the mechanical impulse propagation through a horizontal alignment of elastic spheres of progressively decreasing diameter phi(n): namely, a tapered chain. Experimentally, the diameters of spheres which interact via the Hertz potential are selected to keep as close as possible to an exponential decrease, phi(n+1)...
Article
Full-text available
We study the diffraction in time harmonic regime of an acoustic wave by a rigid plate in the presence of a uniform flow in a duct. Contrary to prior analytical studies, using Wiener–Hopf techniques and thus restricted to semi-infinite plates, we use a finite elements method which allows us to deal with plates of finite length. To take into accoun...
Article
Full-text available
We perform measurements, numerical simulations, and quantitative comparisons with available theory on solitary wave propagation in a linear chain of beads without static preconstraint. By designing a nonintrusive force sensor to measure the impulse as it propagates along the chain, we study the solitary wave reflection at a wall. We show that the m...
Article
Full-text available
The aim of this paper is to study the influence of the shape of the temperature distribution on the thermoacoustic amplification in an annular thermoacoustic prime mover. An analytical model is presented and the acoustic field in the whole device is computed for an arbitrary temperature distribution. The obtained results demonstrate dependence of t...
Article
Full-text available
Experiments with an annular thermoacoustic engine employing quasiadiabatic interaction between traveling acoustic waves and an inhomogeneously heated porous material indicate the presence of a closed-loop mass flux. A qualitative modeling of the enthalpy flux in the thermoacoustic core provides an opportunity to estimate the thermal convection asso...
Article
We propose a new method called "Scattering Matrix by Multimodal Method (S3M)" to compute the scattering matrix of a lined duct with flow. The basis of this method is to project the propagation equations on a complete basis of functions. The transmission and reflection matrices can then be computed easily. The S3M is much more quicker than a finite...
Article
Full-text available
It is demonstrated that the temperature oscillations near the edge of the thermoacoustic stack are highly anharmonic even in the case of harmonic acoustic oscillations in the thermoacoustic engines. In the optimum regime for the acoustically induced heat transfer, the amplitude of the second harmonic of the temperature oscillations is comparable to...
Article
Full-text available
The theory of acoustic streaming in an annular thermoacoustic prime-mover is developed. It is predicted that above the threshold for traveling wave excitation the device considered (which does not contain any moving parts or externally imposed pressure gradients) produces circulation of fluid. The heat flux carried by this directional mass flow ins...
Article
The problem of analytical description of temperature fields and heat fluxes in thermoacoustic devices (such as refrigerators and prime-movers) is discussed. It is demonstrated that for the precise analysis of the thermoacoustic process near the edges of the stacks and the heat exchangers, and also for the prediction of the heat fluxes between the s...
Article
Full-text available
The general relation between the velocity of acoustic streaming and the parameters of the acoustic field in a traveling wave (annular) thermoacoustic device is derived. The effects investigated are important for the optimization of thermoacoustic devices because the acoustic streaming contributes to heat transport. © 2000 American Institute of Phys...
Article
Full-text available
It is demonstrated that the temperature oscillations near the edge of the thermoacoustic stack are highly anharmonic even in the case of harmonic acoustic oscillations in the thermoacoustic engines. In the optimum regime for the acoustically induced heat transfer, the amplitude of the second harmonic of the temperature oscillations is comparable to...
Article
The threshold condition for thermoacoustic instability in an annular prime‐mover is derived. The region of spatially inhomogeneous temperature distribution (due to the presence of a stack and hot and cold heat exchangers) is assumed to be acoustically thin. The interaction of acoustic waves with the stack is assumed to be quasiadiabatic. Theoretica...
Article
Full-text available
Finite-amplitude stationary acoustic waves in a closed resonator subjected to simultaneous excitation at fundamental frequency and its second harmonic are analyzed in the frame of the second-order nonlinear theory. The conditions when the dual-frequency excitation leads to a quality factor Q higher than in the case of a single-frequency excitation...

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