Luc Jaouen

• Matelys - Research Lab

Understanding and predicting the vibro-acoustic behavior of acoustical porous materials (like foams, synthetic or natural fibers, metamaterials...) requires to determine the parameters of their solid and their fluid phases. This work presents an non-exhaustive overview of the methods commonly used to assess the visco-elastic and acoustic parameters...

The computation of the diffuse field response of multilayered homogeneous structures leads to integrals which should be computed efficiently. This is all the more true as the frequency increases, since the integrand has localized peaks. The objective of this communication is to propose an adaptive integration scheme that aims to limit the number of...

When designing passive sound-attenuation structures, one of the challenging problems that arise is optimally distributing acoustic porous materials within a design region so as to maximise sound absorption while minimising material usage. To identify efficient optimisation strategies for this multi-objective problem, several gradient, non-gradient,...

The aim of the work is to study the feasibility of using machine learning techniques to design a decision helper to assist the characterisation of acoustic materials (porous media for instance). The tool is intended to alert the human operator about specific physical phenomena occurring during the measurements or common mistakes in handling the cha...

Comics and manga have long been seen as childish literature, even if sometimes referred to as an art. Webpages discussing matters like Mathematics or Science are usually considered popularized content and not as tools with which research can be built. Arcade video games are often not considered serious games that can be used for learning or team bu...

Engineered wood constructions and timber buildings are rapidly developing, while the numerical techniques usable for their sound insulation properties are various and often still under development. This research constitutes a first step towards the reliability determination of building acoustics simulations on timber-based elements. A small scale r...

Meta-materials have been a subject of great interest in the field of acoustic materials for several years. The term « meta » is used to emphasize that at least one non-conventional phenomenon is used. These meta-materials could also be called multiple dynamic materials. A large number of works are published every year in this field and it may be di...

When designing sound packages, often fully filling the available space with acoustic materials is not the most absorbing solution. Better solutions can be obtained by creating cavities of air pockets, but determining the most optimal shape and topology that maximises sound absorption is a computationally challenging task. Many recent topology optim...

No PDF available ABSTRACT In our modern and highly connected world, we are fed with large and growing amounts of information. As an example, the yearly number of published scientific articles exceeded the astounding number of 1 500 000 papers.in 2015. More and more time is spent on numerical media or supports, with texts that tend to be scanned rat...

The tapping machine has long existed as the primary standard method for measuring the performance of floors in buildings in response to structure-borne noise. However, other sources of structure-borne noise exist. One of these is rolling noise: such as a trolley rolling across the floor in an indoor building environment. Because the sound profile o...

This work presents a prediction model for rolling noise in multi-story buildings, such as that generated by a rolling delivery trolley. Until now, mechanical excitation in multi-story buildings has been limited to impact sources such as the tapping machine. Rolling noise models have been limited to outdoor sources such as trains and automotive vehi...

This work presents a prediction model for rolling noise in multi-story buildings, such as that generated by a rolling delivery trolley. Until now, mechanical excitation in multi-story buildings has been limited to impact sources such as the tapping machine. Rolling noise models have been limited to outdoor sources such as trains and automotive vehi...

Equivalent or condensed plate models are being used in various industries to reduce the computation time in finite element modelling. Out of the available equivalent plate models, the model developed by J.L.Guyader in 1978 exhibits high agreement with Lamb wave theory but it requires some time for implementation. Therefore, in this paper, a simple...

This work presents a prediction model for rolling noise in multi-story buildings, such as that generated by a rolling delivery trolley. Until now, mechanical excitation in multi-story buildings has been limited to impact sources such as the tapping machine. Rolling noise models have been limited to outdoor sources such as trains and automotive vehi...

The tapping machine has long existed as the primary standard method for measuring the performance of floors in buildings in response to structure-borne noise. However, other sources of structure-borne noise exist. One of these is rolling noise: such as a trolley rolling across the floor in an indoor building environment. Because the sound profile o...

Equivalent plate models are commonly used in order to simulate multilayer system as one single layer. This kind of approach enables for instance to reduce the mesh size and thus the number of degrees of freedom in finite element models. Usual condensed model rely on thin plate theory and are obviously limited when considering thick multilayers. In...

The open porosity of air-saturated acoustical porous materials is estimated from the low-frequency or high-frequency asymptotes of the real part of the dynamic bulk modulus. Combining this technique with the estimation of the static air-flow resistivity from the low-frequency asymptote of the imaginary part of the dynamic mass density and the analy...

The use of foam materials as a means of improving the sound absorption and transmission properties of structures, especially at low frequencies, has been receiving considerable attention over the past years. Unfortunately , the underlying complex material domain that may include solid inclusions, renders numerical simulation using the standard FEM...

Structural topology optimisation techniques are increasingly being applied to acoustic materials. Most acoustic topology optimisation applications use the solid-isotropic-material-with-penalization (SIMP) approach which is a derivative-based method. In this work, we study the use of covariance-matrix-adaptation-evolution-strategy (CMA-ES) considere...

In the world of building acoustics, a standard tapping machine has long existed for the purpose of replicating and regulating impact noise. However there still exist other kinds of structure-borne noise which could benefit from being considered when designing a building. One of these types of sources is rolling noise. This report details a proposal...

The optimization of multilayered-sound-packaging is a challenging task which involves searching the best/op-timal settings for a number of acoustic parameters. The search space size becomes too large to handle by brute force, as the number of those parameters increases. In this study, we apply metaheuristics to configure multi-layered porous materi...

The properties of the materials used for building sound proofing systems are known to exhibit large variations. These may lead to significant differences in the acoustic responses within a given material batch, particularly when resistive screens are used as a surface component for a multi-layered absorbing panel. In such thin films, it is mostly t...

In vehicle tire/road contact modeling, dynamic models are typically used which incorporate the vehicle’s suspension in their estimation: thus relying on a known stiffness to determine the movement of the wheel in response to roughness excitation. For the case of a wheeled device rolling on a floor (such as a delivery trolley moving merchandise arou...

When analyzing the effect of damping factor of a simple plate subjected to an airborne excitation, the effect of damping is well known. Its effect is mainly observed around the critical frequency. This observation is no longer valid when looking at other types of excitations (turbulent boundary layer, point force, rainfall, tapping machine ...). Th...

In vehicle tyre/road contact modelling, dynamic models are typically used which incorporate the vehicle's suspension in their estimation: thus relying on a known stiffness to determine the movement of the wheel in response to roughness excitation. For the case of a wheeled device rolling on a floor (such as a delivery trolley moving merchandise ins...

The present dataset contains measurements of the acoustic response of screens in an impedance tube with different backings. It includes as well the characterised parameters for the screens and backings.

New buildings in urban areas are divided into commercial and habitable areas. Commercial shops typically exist on the ground floors, with private residencies on the upper floors. This use has revealed critical disturbances due to the noise generated by rolling delivery carts when the buildings are mainly occupied (e.g. early in the morning). These...

There is a considerable number of research publications on the acoustical properties of porous media with an elastic frame. A simple search through the Web of Science™ (last accessed 21 March 2018) suggests that there are at least 819 publications which deal with the acoustics of poroelastic media. A majority of these researches require accurate kn...

We measured the acoustic absorption, in the 0.5–6 kHz frequency range, of polyurethane foams with mean pore diameters between 0.6 and 3.2 mm. Two types of foams were investigated: classical open-cell ones versus membrane foams, in which thin polyurethane membranes were preserved during solidification. Interestingly, the latter presented better abso...

In this communication, we present a technique to estimate the 6 parameters of the Johnson-Champoux-Allard-Lafarge model for porous media using a classical impedance tube. The estimation of the static air-flow resistivity is obtained from the imaginary part of the dynamic mass density as proposed by Panneton & Olny. The open porosity is estimated f...

There is a considerable number of research publications on the acoustical properties of porous media with an elastic frame. A simple search through the Web of ScienceTM (last accessed 21 March 2018) suggests that there are at least 819 publications which deal with the acoustics of poroelastic media. A majority of these researches require accurate k...

This work focuses on the length correction due to radiation effect of a duct discontinuity or at the surface of a perforated plate in the linear acoustic domain and at large wavelengths. Two results are obtained from the comparison of models used in the literature for different geometries of duct discontinuities or perforations. First, the mode-cou...

This work focuses on the length correction due to radiation effect of a duct discontinuity or at the surface of a perforated plate in the linear acoustic domain and at large wavelengths. Two results are obtained from the comparison of models used in the literature for different geometries of duct discontinuities or perforations. First, the mode-cou...

New buildings in urban areas are divided in commercial and living surfaces. This usage has revealed critical disturbances due to the noise of the trolleys delivering at time where the buildings are mostly occupied, e.g., early times in the morning. Rolling trolleys indeed generate low frequency vibrations (below 100 Hz) which propagate easily in th...

Acoustical facings (including micro perforated panels—MPP—woven and non-woven textiles, screens..) which can be used in association with porous materials, have been widely studied. A large number of models are described in the literature. This work presents a comparison of these models discussing particularly the expression of the corrections relat...

There is a considerable number of research publications on the characterization of porous media that is carried out in accordance with ISO 10534-2 (International Standards Organization, Geneva, Switzerland, 2001) and/or ISO 9053 (International Standards Organization, Geneva, Switzerland, 1991). According to the Web of ScienceTM (last accessed 22 Se...

Acoustical porous materials are commonly used to reduce the noise in the presence of flow. In such applications, it is essential to control how these materials may alter the flow and may regenerate noise. The purpose of this work is to show different ways to take into account the porous materials in Computational Fluid Dynamics (CFD) simulations an...

An analysis of intrinsic dynamic phenomena in anisotropic poroelastic media is presented, based on a plane wave formulation. The latter is derived from the Stroh formalism on the state variables governing the behaviour of such media. A particular interest is given to the compression-shear coupling related to the material alignment of the anisotropi...

Based on a modified equivalent fluid model, the present work proposes a composite model which analytically includes the shape of the inclusions, whether they are porous or not. This model enables to describe the acoustic behavior of a large range of media from perforated plates to arbitrarily shaped porous composites including configurations of por...

Among porous materials, food products represent a large range of micro-structures usually studied in acoustics. These media may indeed include open or closed cell foams, fibrous materials, granular materials, functionally graded materials, porous media with poro-elastic inclusion etc. Therefore, they represent major modeling and experimental challe...

When analyzing the effect of damping factor of a simple plate subjected to airborne excitation, the effect of damping is well known. Its effect is mainly observed around the critical frequency. This observation is no longer valid when looking at other types of excitations (turbulent boundary layer, the point load, rainfall, tapping machine ...). Th...

Different ways to learn or to think about a given topic which are hereafter called perspectives are presented. The field of acoustical porous media is used as an example but it can be applied to any field of knowledge. The first perspective from which a student or a researcher can learn is books or articles. Their modern form: knowledge websites l...

This paper presents an alternative formulation of Biot’s theory to account for the elastic frame effects in a porous medium in which the acoustical properties of the fluid phase are predicted with an equivalent fluid model. This approach was originally developed for a double porosity medium. In this paper, the alternative formulation is applied to...

The Journal of the Acoustical Society of America 134(6), 4589 (2013) DOI: http://doi.org/10.1121/1.4828976

This work aims at linking the in-situ measured surface properties of a given single-layer or multi-layer system to its intrinsic characteristics. The methods for measuring in-situ the surface properties, which are numerous and were proved to be robust, provide however only limited information about the material dissipation mechanisms. For some mate...

Semi-phenomenological models have been widely used since the 1990's for modeling visco-thermal dissipations of acoustical energy through porous media. These dissipations are taken into account by two complex frequency-dependent functions (the dynamic density ρeq (ω) and the dynamic bulk modulus Keq (ω)), which are analytically derived from macrosco...

In this paper, a model for sound propagation in double porosity materials with elastic frame is proposed. The main originality of this paper is to develop a model which is suitable for sound absorbing materials. The original idea is to replace the fluid-phase related properties of a single porosity material in Biot transverse isotropic equations wi...

Perforated facings (including Micro Perforated Panels) or perforated ceiling tiles have been widely studied since the fundamental work by Uno Ingard. This work specially focus on flow modifications in the vicinity of the perforations leading to modifications of the reactance of the panel. This communication is a synthesis study of pioneer and recen...

Impedance tube is widely used to characterize acoustical materials, but it is restricted to frequencies corresponding to plane wave mode propagation. Broadband measurements require testing samples within tubes of different cross-sections: the smaller the diameter the higher the maximum frequency allowed. This is a critical issue for materials or mu...

Ever demanding weight reduction criteria leads to high demands on the vibro-acoustic modeling tool accuracy. These demands face the difficulty of accessibility to the various required parameters and the selection and relevance of the dissipative models. Especially targeted systems are acoustic perforated membrane/fabrics and multi-scale materials,...

This paper examines the potential of using composite porous materials to design robust noise control packages. Composite porous are meso-perforated porous materials in which perforations are filled with another porous material. The work presented here shows that the association of two carefully selected materi-als could lead to interesting combined...

Dynamic visco-elastic characterization of porous material parameters shows a revival of interest since a few years. In this article, a methodology for the assessment of the visco-elastic parameters of soft, highly damped porous materials is presented. This method uses a frequency response function of a free–free bending beam. The global method is b...

An experimental method to estimate the acoustical parameters of perforated facings used for noise control applications is proposed. These perforating facings (also called screens) can be woven or non-woven fabrics or even micro-perforated plates (MPP). Following the work by Atalla and Sgard [J. Sound Vib. 303, 195-208 (2007)], the perforated facing...

This paper is concerned with the analytical modeling of the acoustic properties of materials which could show interesting combined performances of sound absorption and sound insulation. These materials, made from porous materials having porous inclusions, are called composite porous materials by analogy with standard composite materials composed by...

Recycling polymers is attractive to reduce the amount of industrial waste and to limit the traditional dependence on virgin petro-chemical products. In order to produce competitive acoustic products it is important to understand the relationships between the material microstructure and the manufac-turing process parameters. This paper presents resu...

La caractérisation dynamique de paramètres élastiques de matériaux poreux acoustiques fait l'objet d'un regain d'intérêt depuis quelques années ([1]). Dans cet article, on présente une méthode de mesure des faibles modules d'Young et des importants facteurs de pertes des matériaux poreux acoustiques (usuellement de 1 000 à 1 000 000 Pa et 0.05 à 1....

Several characterization methods of porous materials elastic parameters exists (a review of those methods is done in [1]) but Poisson's ratio is the most tricky parameter to get. This paper proposes a quasistatic method for Poisson's ratio assessement of isotropic acoustical porous materials. The method is based on longitudinal and transverse displ...

The combined mechanical and acoustic properties of auxetic (negative Poisson's ratio) foams are described both from a numerical and experimental point of view. Samples of open cell PU-PE foams with negative Poisson's ratio are produced using a dedicated manufacturing process, and subjected to tensile quasi static and cyclic loading, as well as soun...

This paper presents recent developments in the field of micro-acoustics of porous media. The fundamental idea of the proposed approach is that it is possible to assess porous microstructure and acoustical properties from the three-dimensional implementation of micro-acoustics based scaling relations on porous materials. We illustrate this approach...

During lift-off, space launchers are submitted to high-level of acoustic loads, which may damage sensitive equipments. A special acoustic absorber has been previously integrated inside the fairing of space launchers to protect the payload. A new research project has been launched to develop a low cost fairing acoustic protection system using optimi...

The Sound Transmission Loss (STL) of Autoclaved Aerated Concrete (AAC) materials computed with an isotropic elastic model is usually underestimated by 5 to 8dB in the low frequency range (50-400 Hz). A better approximation of AAC STL can be achieved by using a model that also takes into account the porous characteristics of the material. By using t...

This paper addresses the FEM prediction of the vibro-acoustic behavior of an enclosure surrounding a sound source, which is treated using multiscale poroelastic materials.The enclosure consists of a five rigid wall cavity coupled to a flexible metal plate. The plate, the enclosed air and the acoustical treatment are modeled using a finite element m...

Acoustical porous materials like polymer foams or mineral wools are widely used in noise and vibration control. The acoustic efficiencies of these materials may be influenced by their elastic and damping properties. It is thus important to determine parameters such as Young’s or shear moduli, Poisson’s ratios and loss factors.The first objective of...

Non planar acoustic materials may be used in building and environmental acoustics to achieve a significant absorption at low frequencies. Examples of these materials are anechoic wedges or advanced design noise barriers. The shape of these materials is mainly based on empirical knowledge because a fine numerical modeling (e.g. FEM, BEM) requires la...

Despite the numerical advances, predicting the sound field in anechoic rooms is still challenging because it requires a fine modeling of the wall surface, acoustic properties and geometry, and the computation of the room sound field. It is proposed here to compare two innovative approaches to predict the performance of anechoic wedges, in particula...

An analytical model of sound propagation for porous materials with single or double scale of porosity is described. For each scale, pores and interconnections between them are modeled by a serie of two cylinders; a cylindrical periodical cell is thus considered. Scales are supposed to be separated, the porous medium is supposed to be periodic and t...

We propose to illustrate two different uses of multi- scale porous materials: a material with air inclusions (hereafter referred to as a double porosity material) and a material with porous inclusions (hereafter referred to as a composite material). First, a description of the dissipative phenomena related to thermal and viscous effects which occur...

This paper reports the results of reproducibility experiments on the interlaboratory characterization of the acoustical properties of three types of consolidated porous media: granulated porous rubber, reticulated foam, and fiberglass. The measurements are conducted in several independent laboratories in Europe and North America. The studied acoust...

Une étude de l'influence de la précontrainte sur l'estimation des paramètres élastiques de matériaux poreux acoustiques est réalisée. Le dispositif expérimental utilisé pour cette étude, dérivant d'un système masse de précontrainte-ressort, est celui décrit par. Deux classes de comportement de la rigidité en fonction de la précontrainte sont identi...

A series of reproducibility experiments on the characterization of acoustical parameters of selected samples of porous media is carried out on a range of porous samples in several independent laboratories in Europe and North America. The data on the characteristicacoustic impedance and complex propagation constant are presented in this work. In add...

A series of reproducibility experiments on the characterisation of acoustical parameters of selected samples of porous media is carried out on a range of porous samples in several independent laboratories in Europe and North America. The studied acoustical characteristics are the characteristic acoustic impedance and complex propagation constant. T...

This paper discusses the measurements and use of the mechanical properties of porous materials. It starts with a review of the classical methods currently used and concentrates in explaining the assumptions, difficulties and limitations of these methods. Next, it concentrates on two methods: a quasi?static approach accounting for the effect of shap...

This paper presents a simplified numerical model based on a hierarchical trigonometric functions set to predict the low frequency vibration behaviour of a plate backed by a thin foam layer. The base metal plate is excited in bending vibrations with a point load and can have various boundary conditions. The poro-elastic layer is modelled using the m...

Porous media like air-saturated polymer foams with open cells, have a nontrivial frequency-dependent absorption that arises due to viscous and thermal effects at the scale of the rigid frame microstructure. In order to produce multiple scattering at ultrasonic frequencies, mesoscale scatterers are introduced in the porous medium host. The effective...

The Oberst method is widely used for the measurement of the mechanical properties of viscoelastic or damping materials. The application of this method, as described in the ASTM E756 standard, gives good results as long as the experimental set-up does not interfere with the system under test. The main difficulty is to avoid adding damping and mass t...

This work presents two experimental methods for the characterization of elastic and damping properties of acoustic porous materials in dynamic regime. Young's or shear moduli and structural damping coefficients of polymer foams or fibrous materials are estimated in practical conditions, i.e. in bending or shear vibrations for temperature and freque...

Multilayered structures including poro-elastic materials, like polymer foams, are widely used for sound absorption and vibrations damping in buildings and in the transport industries. Predictions of the mechanical behaviour of such structures are usually done with complete classical poro-elastic finite element models which lead to important computa...

To answer the need of characterization and optimization for newly developed foams like met-al or mineral ones, a standing wave tube method for the prediction of the acoustic efficiency of open-cells and air saturated porous material featuring two separate scales of porosity is presented. Materials studied in this paper are supposed to have porosity...