Laboratoire d'Acoustique de l'Université du Maine

Nouvelle traduction : Acoustics and Mechanics of Porous Materials

Jean-Philippe Groby — 2013-03-15T11:35:55Z

The activities of the Acoustics and Mechanics of Porous Materials research group were initiated in the 80's by the research of J. F. Allard (Professor at the University of Le Mans till he retired in 2011). Prof. J.F. Allard received the Biot medal in 2008 and the Decibel d'Or special price in 2011 for his contribution in the modeling of acoustic wave propagation in air saturated porous materials.
Nowadays, the activities of our group focus on the acoustics and dynamic behavior of sound absorbing complex materials, mostly involving porous materials saturated by air, but also some specific research is conducted on porous materials saturated by heavy fluids, like water (bone modeling, geophysics...).
The activities are organized around three topics which are highly interconnected:

the characterization of the acoustic, non-acoustic, and mechanical properties of porous materials and sound absorbing materials
the modeling either aimed at the development of models to describe the propagation of acoustic waves in porous materials in various frequency regimes, or aimed at the numerical modeling of acoustic waves in structures involving porous materials
the design of new complex structures,inspired by metamaterials to enhance the absorption properties of acoustically absorbent materials

Download the research group report of the period 2006-2010
Download the slides of the research group presentation

Positions currently available

The research group is currently looking for one PhD student in one of the following subjects:

Modeling of sound propagation in fluid-solid porous metamaterials with rigid frame
Natural materials for the absorption of audible sound (see announcement)
Metaporous material for the absorption of audible sound (see announcement)

Post-doctoral positions

We are always pleased to invite and hire post-doctoral researchers who have skills in one or several of the research group domains.
Abilities in experimental studies are very welcome but we are also interested in theoretical and numerical skills.
Please do not hesitate to contact us for any further information.

Members

Academic and technical staff:

Bruno BROUARD (MCF)
Bernard CASTAGNÈDE (Pr)
Olivier DAZEL (MCF-HDR)
Claude DEPOLLIER (Pr)
Aroune DUCLOS (MCF)
Jean-Philippe GROBY (CR CNRS), current leader of the research group
Michel HENRY (MCF-HDR)
Denis LAFARGE (CR CNRS)
Stephane LEBON (AI CNRS)
Sohbi SAHRAOUI (Pr)
Vincent TOURNAT (CR CNRS-HDR)
Navid NEMATI (ATER)

PhD students

C. Lagarrigue, Eco-metamaterials for wide band sound absorption, (2010-2013)
J. P. Parra Martinez, Global acoustical thermal optimization methods for sound packages, International PhD cotutelle KTH – ECO2 Center, Sweden (2012-)

Former PhD Students (defence after 2010)

A. Geslain (2008-2011), now post-doc at Leuven Measurement Systems
N. Nemati (2009-2012), now ATER at the Université du Maine

Former visitors

J. Prisutova, PhD student for the University of Bradford (UK) -4 months in 2013-
A. Färn, PhD student from KTH- Royal Institute of Technology (Sweden) -3 months in 2012-
O. Umnova, Senior Lecturer from the University of Salford (UK) -6 months in 2012/2013-
K. Horoshenkov, Professor from the University of Bradford (UK) -1 month in2012-

Current activities

1. Characterization of porous materials

The usual characterization procedures for the recovery of the acoustic and non acoustic parameters of the Johnson-Champoux-Allard model (flowmeter, standard diameter impedance tubes, ultrasounds) and of the mechanical parameters (rigidimeter) have been transfered to the acoustic group of CTTM.

The activities of the research group regarding the characterization of porous materials now focus on:

the recovery of the Pride-Lafarge model parameters by use of a specially designed impedance sensor (see Figure 1) jointly developed by LAUM and CTTM. These parameters are particularly important for the low frequency modeling of the porous materials behavior. This work is conducted in collaboration with CTTM

the characterization of the parameter profiles of macroscopically inhomogeneous porous materials. This work is conducted in collaboration with the University of Bradford
the development of a specific set-up for the measurement of the reflection and absorption coefficients of sound absorbing materials with a single microphone
the mechanical characterization of porous materials, in particular anisotropic and compressed foams, by use of the rigidimeter shown Figure 2. This work is conducted in collaboration with CTTM

the mechanical characterization of porous materials by use of surface acoustic waves. This work is conducted in collaboration with the KULeuven and the Université de Bourgogne

2. Modeling

Besides some of the widely used models to describe the acoustic propagation in air saturated porous materials developed at the Laboratory (Johnson-Champoux-Allard model or Pride-Lafarge model), the modeling of porous metamaterials is currently of particular importance. A nonlocal model accounting for both time and spatial dispersion of the acoustic propagation in acoustic metamaterials has been recently developed in the laboratory and is currently one of the most relevant ongoing work of the group on physical models.

Regarding numerical modeling of the acoustic wave propagation in structure involving porous materials various in-house codes have been developed:

a stable Transfer Matrix Method, allowing for the simulation of the acoustic wave propagation in multilayer structures, involving alternatively elastic, poroelastic, equivalent fluid, or fluid layers has been recently developed. This method avoids crashes and divergence of the calculations sometimes encountered with TMM procedures as well as it benefits from a decreased number of unknowns compared with classical TMM
some in-house Finite-Element code for the solution of the acoustic response of
- axisymmetric problems involving poroelastic materials, double porosity poroelastic materials
- periodic structures involving porous materials, see for example Figure 3

a reformulation of the Biot theory (Dazel et al. 2007) that is suitable for numerical and semi-analytical calculations, see for example Figure 4

reduced model techniques, which enable the calculations of the acoustic response of complex structures by a use of a judiciously chosen number of mode in each substructure that composed to whole complex structure, see for example Figure 5

specific semi-analytical codes to solve multi-scattering problems
developments of discontinuous Galerkin methods with plane waves for sound absorbing materials. This work is conducted in collaboration with the Institute of Sound and Vibration Research, University of Southampton (UK)

3. Sound absorption and control by complex structures

Classical sound absorbing porous materials suffer from a lack of absorption at low frequency, when compared to their efficiency at higher frequency. This is due to the intrinsic absorption mechanisms, which only rely on the viscous and thermal losses. To enhance the absorption of porous based complex structures, porous materials should be combined with volume or surface heterogeneities. The excitation of the resonances due to the presence of heterogeneities and/or to the resonant heterogeneities themselves induces a localization of the energy inside the structures and therefore an enhancement of absorption properties.

Several configurations are studied as a first step:

resonant sonic crystals, possibly made of natural materials, for their abnormal transmission combining bandgaps due to periodicity with those associated to resonances of the scatterers, see Figure 6

sonic crystals composed of non-circular cross section scatterers for their tunability as well as their ability to guide acoustic waves and perform multiplexing
macroscopically inhomogeneous porous materials, either poroelastic or under the rigid frame approximation, for their ability to combine adaptation of the impedance between the porous material and the air medium with large absorption properties associated with increasing flow resistivity profiles. These research on graded porous materials are conducted in collaboration with the Université de Bourgogne and the University of Bradford

The second step consists of embedding inclusions, possibly resonant, inside porous materials, and possibly coupled with surface irregularities leading to metaporous materials. These metaporous materials present quite enhanced absorption properties. Sound absorption can be higher than 0.9 for wavelength 10 times larger than the thickness of the structures, see for example Figures 3 and 7. This research is conducted in collaboration with the University of Salford and Supmeca.

Some movies showing the snapshot of the pressure field inside the unit cell as a function of frequency along the absorption curve can be found on youtube in the case of:

a 2 cm thick Fireflex foam with 3 circular inclusions and an irregularity of the rigid backing, here
a 2.1 cm thick Melamine foam with periodic split-ring resonators embedded in with alternate orientations, here

Collaboration

Acoustics and Thermal Physics, KULeuven, Belgium
Department of Aeronautical and Vehicle Engineering, KTH Royal Institute of Technology, Sweden
Center for sustainable development, University of Bradford, UK University of Salford, UK
Institute of Sound and Vibration Research, University of Southampton, UK
Laboratoire de Mécanique et d'Acoustique, Marseille, France
The phononic group of IEMN, Lille, France
The Center of Technology Transfer of Le Mans, France
Supméca, Saint-Ouen, France
Université de Bourgogne, ISAT, Nevers, France
ENTPE, Vaulx en Velin, France

Defence (since 2010)

PhD

A. Geslain (2011), Natural and induced anisotropy of porous materials: Experiments and modeling, download the PhD here
N. Nemati (2012), Macroscopic theory of sound propagation in rigid-framed porous materials allowing for spatial dispersion: principle and validation

HDR

O. Dazel (2011), Numerical methods for the Biot theory in acoustics, download the manuscript here

Award (since 2010)

J.F. Allard, Decibel d'Or special price in 2011 for his contribution in the modeling of acoustic wave propagation in air saturated porous materials

Publications (since 2010)

2010

J.-P. Groby, E. Ogam, L. De Ryck, N. Sebaa, and W. Lauriks, Analytical method for ultrasonic characterization of homogeneous rigid porous materials from transmitted and reflected coefficients, Journal of the Acoustical Society of America, 127: 764-772, 2010.
J.-P. Groby, W. Lauriks, and T.E. Vigran, Total absorption peak by use of a rigid frame porous layer backed with a rigid multi-irregularities grating, Journal of the Acoustical Society of America, 127: 2865-2874, 2010.
O. Dazel, B. Brouardn N. Dauchez, A. Geslain, and CH Lamarque, A Free Interface CMS Technique to the Resolution of Coupled Problem Involving Porous Materials, Application to a Monodimensional Problem, Acta Acustica united with Acustica, 96: 247-257, 2010.
O. Dazel and V. Tournat, Nonlinear Biot waves in porous media with application to unconsolidated granular media, Journal of the Acoustical Society of America, 127: 692-702, 2010.
E. Ogam, C.Depollier, and Z.E.A. Fellah, The direct problem of acoustic diffraction of an audible probe radiation by an air-saturated porous cylinder, Journal of Applied Physics, 108: 113519, 2010.
E. Ogam, C.Depollier, and Z.E.A. Fellah, The direct and inverse problems of an air-saturated porous cylinder submitted to acoustic radiation, Review of Scientific instruments, 81: 094902, 2010.

2011

E. Ogam, Z.E.A. Fellah, N. Sebaa, and J.-P. Groby, Non-ambiguous recovery of Biot poroelastic parameters of cellular panels using transmitted ultrasonic waves, Journal of Sound and Vibration, 330: 1074-1090, 2011.
J.-F. Allard, O. Dazel, G. Gautier, J.-P. Groby, and W. Lauriks, Prediction of sound reflexion by corrugated porous surfaces, Journal of the Acoustical Society of America, 129: 1696-1706, 2011.
J.-P. Groby, A. Duclos, O. Dazel, L. Boeckx, et W. Lauriks, Absorption of a rigid frame porous layer with periodic circular inclusions backed by a periodic grating, Journal of the Acoustical Society of America, 129: 3035-3046, 2011.
J. Descheemaeker, C. Glorieux, W. Lauriks, J.-P. Groby, L. Boeckx, and P. Leclaire, Study of circumfential waves on a layered poroelestic cylinder, Acta Acoustica united with Acustica, 97: 734-743, 2011.
A. Geslain, O. Dazel, S. Sahraoui, J.-P. Groby, and W. Lauriks, Influence of static compression on mechanical parameters of acoustic foams, Journal of the Acoustical Society of America, 130: 818-825, 2011.
G. Gautier, J.P. Groby, O. Dazel, L. Kelders, L. De Ryck, and P. Leclaire, Propagation of acoustic waves in a one-dimensional macroscopically inhomogeneous poroelastic material, Journal of the Acoustical Society of America, 130: 1390-1398, 2011.
M. Sadouki, M. Fellah, Z.E.A. Fellah, Z. E. A., E. Ogam, N. Sebaa, F.G. Mitri, and C. Depollier, Measuring static thermal permeability and inertial factor of rigid porous materials, Journal of the Acoustical Society of America, 130: 2627-2630, 2011.
J.-P. Groby, A. Duclos, O. Dazel, L. Boeckx, and L. Kelders, Enhancing absorption coefficient of a backed rigid frame porous layer by embedding circular periodic inclusions, Journal of the Acoustical Society of America, 130: 3771-3780, 2011.

2012

J.-P. Groby, E. Ogam, A. Wirgin, et S. Xu, Recovery of material parameters of a soft elastic layer, Complex Variables and Elliptic Equations, 57: 317-336, 2012.
B. Nennig, Y. Renou, J.-P. Groby, and Y. Aurégan, A mode matching approach for modeling 2D porous grating with rigid or soft incluions, Journal of the Acoustical Society of America, 131: 3841-3852, 2012.
A. Geslain, J.-P. Groby, O. Dazel, S. Mahasaranon, K. V. Horoshenkov, and A. Khan, An application of the Peano series expansion to predict sound propagation in materials with continuous pore stratification, Journal of the Acoustical Society of America, 132: 208-215, 2012.
J.-P. Groby, O. Dazel, C. Depollier, E. Ogam, and L. Kelders, Scattering of acoustic waves by macroscopically inhomogeneous poroelastic tubes, Journal of the Acoustical Society of America, 132: 477-486, 2012.
H. Pichard O. Richoux, and J.-P. Groby, Experimental demonstrations in audible frequency range of band gap tunability and negative refraction in two-dimensional sonic crystal, Journal of the Acoustical Society of America, 132: 2816-2822, 2012.
O. Dazel, F. X. Becot, and L. Jaouen, Biot Effects for Sound Absorbing Double Porosity Materials, Acta Acustica united with Acustica, 98: 567-576, 2012.
J.B. Legland, V. Tournat, O. Dazel, A. Novak, and V. Gusev, Linear and nonlinear Biot waves in a noncohesive granular medium slab: Transfer function, self-action, second harmonic generation, Journal of the Acoustical Society of America, 131: 4292-4303, 2012.

2013

C. Lagarrigue, J.-P. Groby, and V. Tournat, Sustainable sonic crystal made of resonating bamboo rods, Journal of the Acoustical Society of America, 133: 247-254, 2013.
J.-P. Groby, B. Brouard, O. Dazel, B. Nennig, and L. Kelders, Enhancing the absorption of a rigid frame porous layer by use of a rigid backing with three-dimensional periodic multi-irregularities, Journal of the Acoustical Society of America, 133: 821-831, 2013.
O. Dazel, J.-P. Groby, B. Brouard, and C. Potel, A stable method to model the acoustic response of multilayered structures, Journal of Applied Physics, 113: 083506, 2013.

Contact

For additional information, please contact
Jean-Philippe Groby
email: Jean-Philippe.Groby univ-lemans.fr
Phone: +33 2 43 83 36 70

Acoustique et mécanique des matériaux poreux

Jean-Philippe Groby — 2013-03-05T11:03:19Z

The activities of the Acoustics and Mechanics of Porous Materials research group were initiated in the 80's by the research of J. F. Allard (Professor at the University of Le Mans till he retired in 2011). Prof. J.F. Allard received the Biot medal in 2008 and the Decibel d'Or special price in 2011 for his contribution in the modeling of acoustic wave propagation in air saturated porous materials.
Nowadays, the activities of our group focus on the acoustics and dynamic behavior of sound absorbing complex materials, mostly involving porous materials saturated with air, but also some specific research is conducted on porous materials saturated by heavy fluids, like water (bone modeling, geophysics...).
The activities are organized around three topics which are highly interconnected :

the characterization of the acoustic, non-acoustic, and mechanical properties of porous materials and sound absorbing materials
the modeling either aimed at the development of models to describe the propagation of acoustic waves in porous materials in various frequency regimes, or aimed at the numerical modeling of acoustic waves in structures involving porous materials
the design of new complex structures,inspired by metamaterials to enhance the absorption properties of acoustically absorbent materials

Download the research group report of the period 2006-2010
Download the slides of the research group presentation

Positions currently available

The research group is currently looking for one PhD student in one of the following subjects :

Modeling of sound propagation in fluid-solid porous metamaterials with rigid frame
Natural materials for the absorption of audible sound (see announcement)
Metaporous material for the absorption of audible sound (see announcement)

Post-doctoral positions

Members

Academic and technical staff :

Bruno BROUARD (MCF)
Bernard CASTAGNÈDE (Pr)
Olivier DAZEL (MCF-HDR)
Claude DEPOLLIER (Pr)
Aroune DUCLOS (MCF)
Jean-Philippe GROBY (CR CNRS), current leader of the research group
Michel HENRY (MCF-HDR)
Denis LAFARGE (CR CNRS)
Stephane LEBON (AI CNRS)
Sohbi SAHRAOUI (Pr)
Vincent TOURNAT (CR CNRS-HDR)
Navid NEMATI (ATER)

PhD students

C. Lagarrigue, Eco-metamaterials for wide band sound absorption, (2010-2013)
J. P. Parra Martinez, Global acoustical thermal optimization methods for sound packages, International PhD cotutelle KTH – ECO2 Center, Sweden (2012-)

Former PhD Students (defence after 2010)

A. Geslain (2008-2011), now post-doc at Leuven Measurement Systems
N. Nemati (2009-2012), now ATER at the Université du Maine

Former visitors

J. Prisutova, PhD student for the University of Bradford (UK) -4 months in 2013-
A. Färn, PhD student from KTH- Royal Institute of Technology (Sweden) -3 months in 2012-
O. Umnova, Senior Lecturer from the University of Salford (UK) -6 months in 2012/2013-
K. Horoshenkov, Professor from the University of Bradford (UK) -1 month in2012-

Current activities

1. Characterization of porous materials

The activities of the research group regarding the characterization of porous materials now focus on :

the recovery of the Pride-Lafarge model parameters by use of a specially designed impedance sensor (see Figure 1) jointly developed by LAUM and CTTM. These parameters are particularly important for the low frequency modeling of the porous materials behavior. This work is conducted in collaboration with CTTM

the characterization of the parameter profiles of macroscopically inhomogeneous porous materials. This work is conducted in collaboration with the University of Bradford
the development of a specific set-up for the measurement of the reflection and absorption coefficients of sound absorbing materials with a single microphone
the mechanical characterization of porous materials, in particular anisotropic and compressed foams, by use of the rigidimeter shown Figure 2. This work is conducted in collaboration with CTTM

the mechanical characterization of porous materials by use of surface acoustic waves. This work is conducted in collaboration with the KULeuven and the Université de Bourgogne

2. Modeling

Regarding numerical modeling of the acoustic wave propagation in structure involving porous materials various in-house codes have been developed :

a stable Transfer Matrix Method, allowing for the simulation of the acoustic wave propagation in multilayer structures, involving alternatively elastic, poroelastic, equivalent fluid, or fluid layers has been recently developed. This method avoids crashes and divergence of the calculations sometimes encountered with TMM procedures as well as it benefits from a decreased number of unknowns compared with classical TMM
some in-house Finite-Element code for the solution of the acoustic response of
- axisymmetric problems involving poroelastic materials, double porosity poroelastic materials
- periodic structures involving porous materials, see for example Figure 3

a reformulation of the Biot theory (Dazel et al. 2007) that is suitable for numerical and semi-analytical calculations, see for example Figure 4

reduced model techniques, which enable the calculations of the acoustic response of complex structures by a use of a judiciously chosen number of mode in each substructure that composed to whole complex structure, see for example Figure 5

specific semi-analytical codes to solve multi-scattering problems
developments of discontinuous Galerkin methods with plane waves for sound absorbing materials. This work is conducted in collaboration with the Institute of Sound and Vibration Research, University of Southampton (UK)

3. Sound absorption and control by complex structures

Several configurations are studied as a first step :

resonant sonic crystals, possibly made of natural materials, for their abnormal transmission combining bandgaps due to periodicity with those associated to resonances of the scatterers, see Figure 6

sonic crystals composed of non-circular cross section scatterers for their tunability as well as their ability to guide acoustic waves and perform multiplexing
macroscopically inhomogeneous porous materials, either poroelastic or under the rigid frame approximation, for their ability to combine adaptation of the impedance between the porous material and the air medium with large absorption properties associated with increasing flow resistivity profiles. These research on graded porous materials are conducted in collaboration with the Université de Bourgogne and the University of Bradford

Some movies showing the snapshot of the pressure field inside the unit cell as a function of frequency along the absorption curve can be found on youtube in the case of :

a 2 cm thick Fireflex foam with 3 circular inclusions and an irregularity of the rigid backing, here
a 2.1 cm thick Melamine foam with periodic split-ring resonators embedded in with alternate orientations, here

Collaboration

Acoustics and Thermal Physics, KULeuven, Belgium
Department of Aeronautical and Vehicle Engineering, KTH Royal Institute of Technology, Sweden
Center for sustainable development, University of Bradford, UK University of Salford, UK
Institute of Sound and Vibration Research, University of Southampton, UK
Laboratoire de Mécanique et d'Acoustique, Marseille, France
The phononic group of IEMN, Lille, France
The Center of Technology Transfer of Le Mans, France
Supméca, Saint-Ouen, France
Université de Bourgogne, ISAT, Nevers, France
ENTPE, Vaulx en Velin, France

Defence (since 2010)

PhD

A. Geslain (2011), Natural and induced anisotropy of porous materials : Experiments and modeling, download the PhD here
N. Nemati (2012), Macroscopic theory of sound propagation in rigid-framed porous materials allowing for spatial dispersion : principle and validation

HDR

O. Dazel (2011), Numerical methods for the Biot theory in acoustics, download the manuscript here

Award (since 2010)

J.F. Allard, Decibel d'Or special price in 2011 for his contribution in the modeling of acoustic wave propagation in air saturated porous materials

Publications (since 2010)

2010

J.-P. Groby, E. Ogam, L. De Ryck, N. Sebaa, and W. Lauriks, Analytical method for ultrasonic characterization of homogeneous rigid porous materials from transmitted and reflected coefficients, Journal of the Acoustical Society of America, 127 : 764-772, 2010.
J.-P. Groby, W. Lauriks, and T.E. Vigran, Total absorption peak by use of a rigid frame porous layer backed with a rigid multi-irregularities grating, Journal of the Acoustical Society of America, 127 : 2865-2874, 2010.
O. Dazel, B. Brouardn N. Dauchez, A. Geslain, and CH Lamarque, A Free Interface CMS Technique to the Resolution of Coupled Problem Involving Porous Materials, Application to a Monodimensional Problem, Acta Acustica united with Acustica, 96 : 247-257, 2010.
O. Dazel and V. Tournat, Nonlinear Biot waves in porous media with application to unconsolidated granular media, Journal of the Acoustical Society of America, 127 : 692-702, 2010.
E. Ogam, C.Depollier, and Z.E.A. Fellah, The direct problem of acoustic diffraction of an audible probe radiation by an air-saturated porous cylinder, Journal of Applied Physics, 108 : 113519, 2010.
E. Ogam, C.Depollier, and Z.E.A. Fellah, The direct and inverse problems of an air-saturated porous cylinder submitted to acoustic radiation, Review of Scientific instruments, 81 : 094902, 2010.

2011

E. Ogam, Z.E.A. Fellah, N. Sebaa, and J.-P. Groby, Non-ambiguous recovery of Biot poroelastic parameters of cellular panels using transmitted ultrasonic waves, Journal of Sound and Vibration, 330 : 1074-1090, 2011.
J.-F. Allard, O. Dazel, G. Gautier, J.-P. Groby, and W. Lauriks, Prediction of sound reflexion by corrugated porous surfaces, Journal of the Acoustical Society of America, 129 : 1696-1706, 2011.
J.-P. Groby, A. Duclos, O. Dazel, L. Boeckx, et W. Lauriks, Absorption of a rigid frame porous layer with periodic circular inclusions backed by a periodic grating, Journal of the Acoustical Society of America, 129 : 3035-3046, 2011.
J. Descheemaeker, C. Glorieux, W. Lauriks, J.-P. Groby, L. Boeckx, and P. Leclaire, Study of circumfential waves on a layered poroelestic cylinder, Acta Acoustica united with Acustica, 97 : 734-743, 2011.
A. Geslain, O. Dazel, S. Sahraoui, J.-P. Groby, and W. Lauriks, Influence of static compression on mechanical parameters of acoustic foams, Journal of the Acoustical Society of America, 130 : 818-825, 2011.
G. Gautier, J.P. Groby, O. Dazel, L. Kelders, L. De Ryck, and P. Leclaire, Propagation of acoustic waves in a one-dimensional macroscopically inhomogeneous poroelastic material, Journal of the Acoustical Society of America, 130 : 1390-1398, 2011.
M. Sadouki, M. Fellah, Z.E.A. Fellah, Z. E. A., E. Ogam, N. Sebaa, F.G. Mitri, and C. Depollier, Measuring static thermal permeability and inertial factor of rigid porous materials, Journal of the Acoustical Society of America, 130 : 2627-2630, 2011.
J.-P. Groby, A. Duclos, O. Dazel, L. Boeckx, and L. Kelders, Enhancing absorption coefficient of a backed rigid frame porous layer by embedding circular periodic inclusions, Journal of the Acoustical Society of America, 130 : 3771-3780, 2011.

2012

J.-P. Groby, E. Ogam, A. Wirgin, et S. Xu, Recovery of material parameters of a soft elastic layer, Complex Variables and Elliptic Equations, 57 : 317-336, 2012.
B. Nennig, Y. Renou, J.-P. Groby, and Y. Aurégan, A mode matching approach for modeling 2D porous grating with rigid or soft incluions, Journal of the Acoustical Society of America, 131 : 3841-3852, 2012.
A. Geslain, J.-P. Groby, O. Dazel, S. Mahasaranon, K. V. Horoshenkov, and A. Khan, An application of the Peano series expansion to predict sound propagation in materials with continuous pore stratification, Journal of the Acoustical Society of America, 132 : 208-215, 2012.
J.-P. Groby, O. Dazel, C. Depollier, E. Ogam, and L. Kelders, Scattering of acoustic waves by macroscopically inhomogeneous poroelastic tubes, Journal of the Acoustical Society of America, 132 : 477-486, 2012.
H. Pichard O. Richoux, and J.-P. Groby, Experimental demonstrations in audible frequency range of band gap tunability and negative refraction in two-dimensional sonic crystal, Journal of the Acoustical Society of America, 132 : 2816-2822, 2012.
O. Dazel, F. X. Becot, and L. Jaouen, Biot Effects for Sound Absorbing Double Porosity Materials, Acta Acustica united with Acustica, 98 : 567-576, 2012.
J.B. Legland, V. Tournat, O. Dazel, A. Novak, and V. Gusev, Linear and nonlinear Biot waves in a noncohesive granular medium slab : Transfer function, self-action, second harmonic generation, Journal of the Acoustical Society of America, 131 : 4292-4303, 2012.

2013

C. Lagarrigue, J.-P. Groby, and V. Tournat, Sustainable sonic crystal made of resonating bamboo rods, Journal of the Acoustical Society of America, 133 : 247-254, 2013.
J.-P. Groby, B. Brouard, O. Dazel, B. Nennig, and L. Kelders, Enhancing the absorption of a rigid frame porous layer by use of a rigid backing with three-dimensional periodic multi-irregularities, Journal of the Acoustical Society of America, 133 : 821-831, 2013.
O. Dazel, J.-P. Groby, B. Brouard, and C. Potel, A stable method to model the acoustic response of multilayered structures, Journal of Applied Physics, 113 : 083506, 2013.

Contact

For additional information, please contact
Jean-Philippe Groby
email : Jean-Philippe.Groby univ-lemans.fr
Phone : +33 2 43 83 36 70

bidon

stéphane — 2013-02-07T09:32:26Z

bidon - Soutenances de thèses

bidon

stéphane — 2013-02-07T09:27:27Z

bidon - Séminaires

Champs acoustiques en mélanges gazeux thermovisqueux : phénomène de diffusion mutuelle et de pré-condensation aux parois

stéphane — 2012-10-31T08:24:11Z

"Champs acoustiques en mélanges gazeux thermovisqueux : phénomène de diffusion mutuelle et de pré-condensation aux parois"

par Cécile Guianvarc'h,

le mardi 13 novembre à 11h00, salle de conférence du Bât. IAM au 4e étage

Résumé : _

Soutenance de Thèse de Gaël FAVRAUD

stéphane — 2012-10-23T12:37:35Z

Soutenance de Thèse de Gaël FAVRAUD

JEUDI 8 NOVEMBRE 2012 à 14h, Salle de conférences - Bât IAM - 4ième étage

Pour obtenir le grade de DOCTEUR DE L'UNIVERSITÉ DU MAINE
Spécialité : ACOUSTIQUE

Sujet :

devant le jury composé de :

Résumé :

Soutenance de Thèse de Sylvain MEZIL

stéphane — 2012-10-19T13:10:28Z

Soutenance de Thèse de Sylvain MEZIL

MARDI 6 NOVEMBRE à 11h, Salle de conférences - Bât IAM - 4ième étage

Pour obtenir le grade de DOCTEUR DE L'UNIVERSITÉ DU MAINE
Spécialité : ACOUSTIQUE

Sujet :

Méthode optoacoustique non linéaire pour la détection et la caractérisation de fissures

devant le jury composé de :

Claire Prada Directrice de Recherche, Institut Langevin, ESPCI, Paris Rapporteure
Olivier Bou Matar Professeur, IEMN, Lille Rapporteur
Danièle Fournier Professeure Émerite, INSP, Paris Examinatrice
Lili Ganjehi Ingénieure-Chercheure, CEA, Saclay Examinatrice
Thomas Dehoux Chargé de Recherche, LMP, Talence Examinateur
Vincent Tournat Chargé de Recherche HDR, LAUM, Le Mans Directeur de thèse
Vitalyi Gusev Professeur, IMMM, Le Mans Co-directeur de thèse
Nikolay Chigarev Ingénieur de Recherche, LAUM, Le Mans Co-encadrant

Résumé :

L'utilisation des ultrasons lasers est très répandue dans le domaine du contrôle non destructif. L'utilisation des lasers permet de générer des ondes acoustiques de quelques Hz à plusieurs GHz, et donc d'opérer avec des longueurs d'onde suffisamment courtes pour détecter de petits défauts ou tester de petits objets comme les MEMS (Micro-Electro-Mechanical Systems). La résolution spatiale de ces méthodes est souvent très bonne grâce à la possibilité de focaliser les faisceaux laser à l'échelle micrométrique. L'absence de contact avec le matériau testé permet de travailler dans des conditions de pression ou de température extrêmes, et de s'affranchir des non-linéarités liées à l'utilisation des transducteurs piézo-éléctriques. D'autre part, les possibilités offertes par les méthodes acoustiques non linéaires pour le contrôle non destructif sont remarquables (sensibilité à la présence de défauts, extraction de paramètres quantitatifs,...). De nombreuses méthodes acoustiques non linéaires ont vues le jour ces dernières années, parmi lesquelles les méthodes de modulation non linéaire d'une onde par une autre.

L'idée de départ de cette thèse est la mise en oeuvre conjointe de méthodes acoustiques non linéaires et de méthodes opto-acoustiques afin de profiter notamment de la sensibilité à la présence de défauts des premières et de la résolution spatiale, de la large bande fréquentielle utile, et de la nature sans contact des secondes. Cependant, l'efficacité de la conversion opto-acoustique est bien plus faible que la conversion électro-mécanique des transducteurs piézo-électriques, ce qui rend complexe la génération d'effets non linéaires acoustiques avec des lasers. Dans la méthode développée, une onde thermo-élastique à basse fréquence fL ( Hz) et une onde acoustique à haute fréquence fH (dizaines de kHz) sont générées par l'absorption à la surface d'un échantillon de deux faisceaux lasers indépendamment modulés en intensité. Si une fissure est présente dans la zone chauffée, la fissure ‘respire' : elle s'ouvre et se referme sous l'action de la contrainte thermo-élastique photo-générée à fL. L'évolution périodique (ouverte/fermée) de la fissure entraîne un mélange de fréquence non linéaire avec l'onde acoustique générée au même endroit, à l'origine de lobes de modulation aux fréquences fH ± n fL (n=1,2,...), absents en l'absence de fissure. La détection de ces fréquences de mélange révèle donc la présence d'une fissure dans la zone échauffée.

La méthode développée est dans un premier temps validée sur des balayages 1D puis des images 2D. L'influence de divers paramètres expérimentaux (fréquence fL, focalisation,...) sur la génération des lobes non linéaires et la résolution spatiale est étudiée expérimentalement et théoriquement. Un montage intégralement optique (excitation et détection) est également réalisé.

Dans un deuxième temps, l'évolution des amplitudes et phases des lobes non linéaires en fonction de la puissance du faisceau de pompe est étudiée expérimentalement et théoriquement via un modèle comportemental de fissure. La comparaison entre le modèle et l'expérience permet l'évaluation de plusieurs paramètres quantitatifs et locaux de la fissure, dont sa rigidité et son épaisseur.

Soutenance de Thèse de Jean-Baptiste DOC

stéphane — 2012-10-19T13:06:11Z

Soutenance de Thèse de Jean-Baptiste DOC

MERCREDI 7 NOVEMBRE 2012 à 14h, Salle de conférences - Bât IAM - 4ième étage

Pour obtenir le grade de DOCTEUR DE L'UNIVERSITÉ DU MAINE
Spécialité : ACOUSTIQUE

Sujet :

Approximations unidirectionnelles de la propagation acoustique en guides d'ondes irréguliers - Application à l'acoustique urbaine

devant le jury composé de :

Ph. Blanc-Benon Directeur de recherche, LMFA, Lyon Rapporteur
F. Coulouvrat Directeur de recherche, IJLRDA, Paris Rapporteur
M. Deschamps Directeur de recherche, I2M, Bordeaux Examinateur
S. Félix Chargé de recherche, LAUM, Le Mans Co-encadrant
B. Gauvreau Chargé de recherche, IFSTTAR, Nantes Invité
B. Lihoreau Maître de conférences, LAUM, Le Mans Co-encadrant
V. Pagneux Directeur de recherche, LAUM, Le Mans Directeur de thèse

Résumé :

L'environnement urbain est le siège de fortes nuisances sonores notamment générées par les moyens de transport. Afin de lutter contre ces nuisances, la réglementation européenne impose la réalisation de cartographies de bruit. Dans ce contexte, des travaux fondamentaux sont menés autour de la propagation d'ondes acoustiques basses fréquences en milieu urbain. Différents travaux de recherche récents portent sur la mise en œuvre de méthodes ondulatoires pour la propagation d'ondes acoustiques dans de tels milieux. Le coût numérique de ces méthodes limite cependant leur utilisation dans un contexte d'ingénierie. L'objectif de ces travaux de thèse porte sur l'approximation unidirectionnelle de la propagation des ondes, appliquée à l'acoustique urbaine. Cette approximation permet d'apporter des simplifications à l'équation d'onde afin de limiter le temps de calcul lors de sa résolution. La particularité de ce travail de thèse réside dans la prise en compte des variations, continues ou discontinues, de la largeur des rues. Deux formalismes sont utilisés : l'équation parabolique et une approche multimodale. L'approche multimodale sert de support à une étude théorique sur les mécanismes de couplages de modes dans des guides d'ondes irréguliers bidimensionnels. Pour cela, le champ de pression est décomposé en fonction du sens de propagation des ondes à la manière d'une série de Bremmer. La contribution particulière de l'approximation unidirectionnelle est étudiée en fonction des paramètres géométriques du guide d'ondes, ce qui permet de mieux cerner les limites de validité de cette approximation. L'utilisation de l'équation parabolique a pour but une application à l'acoustique urbaine. Une transformation de coordonnées est associée à l'équation parabolique grand angle afin de prendre en compte l'effet de la variation de la section du guide d'ondes. Une méthode de résolution est alors spécifiquement développée et permet une évaluation précise du champ de pression. D'autre part, une méthode de résolution de l'équation parabolique grand angle tridimensionnelle est adaptée à la modélisation de la propagation acoustique en milieu urbain. Cette méthode permet de tenir compte des variations brusques ou continues de la largeur de la rue. Une comparaison avec des mesures sur maquette de rue à échelle réduite permet de mettre en avant les possibilités de la méthode. _

Modélisation numérique des guides d'ondes courbes : application à l'élastodynamique de structures hélicoïdales et multi-brins

Simon Félix, stéphane — 2012-10-16T10:59:34Z

"Modélisation numérique des guides d'ondes courbes : application à l'élastodynamique de structures hélicoïdales et multi-brins"

par Fabien Treyssède, Ifsttar, Nantes

le mardi 18 septembre à 11h00, en salle de conférence (bât. IAM, 4^e étage)

Résumé : Nous présentons ici une méthode d'investigation numérique des ondes guidées dans les structures courbes. Dans un contexte général, nous discutons d'abord de l'existence des modes de propagation dans les guides courbes. La propriété d'invariance par translation, implicitement utilisée pour l'analyse des guides droits, est redéfinie pour les systèmes de coordonnées curvilignes. Nous montrons que l'écriture des équations de la physique dans un système hélicoïdal permet de satisfaire cette invariance. Notre étude est ensuite particularisée aux guides d'ondes mécaniques. Étant donné la difficulté d'obtenir des solutions analytiques, une approche purement numérique est adoptée, basée sur la méthode des éléments finis dite semi-analytique. Les câbles du génie civil, dont la structure est généralement hélicoïdale et multi-brins, constituent l'application phare des travaux présentés. Cette structure multi-brins complique la question de l'existence des modes guidés. Nous montrons qu'un système de coordonnées tournant, cas particulier du système hélicoïdal, permet de satisfaire la propriété d'invariance par translation. Enfin, nous discutons brièvement d'autres phénomènes compliquant davantage la modélisation de la propagation des ondes dans les câbles (effets de précontrainte, présence d'une matrice solide enrobant les guides, interaction ondes-défauts).

Modelling of the acoustical properties of periodic arrays of small resonant scatterers in a porous matrix

stéphane — 2012-10-16T10:59:04Z

"Modelling of the acoustical properties of periodic arrays of small resonant scatterers in a porous matrix"

par Olga Umnova, University of Salford, RU

le mardi 11 septembre à 11h00, salle de conférence du Bât. IAM au 4e étage

Résumé :
It is well known that infinite periodic arrays of resonant scatterers (for instance split rings) in air can possess stop-bands at low frequencies. Around bandgap frequencies finite size arrays act as reflective screens, allowing very little sound transmission through them. Recently it has been demonstrated in the numerically, that when arrays of split rings are embedded in a layer of porous foam with a rigid backing, a nearly total absorption of sound can be achieved at frequencies well below the usual 1/4 wavelength resonance range. Moreover the position of the absorption peak depends strongly on the orientation of the resonator openings - the lowest peak frequency is achieved when the openings face the rigid backing.

This work is an attempt to develop a semi-analytical model of these and other phenomena happening when periodically arranged split ring resonators are immersed in a porous matrix.

The properties of a single split ring are considered first. Its resonant frequency in a porous matrix is estimated and is shown to be much lower than that in air if for porous materials with high tortuosity values. Then the influence of the rigid wall on the resonant frequency is investigated. The radiating impedance of the resonator opening facing the rigid wall is calculated. It is demonstrated that in this case an additional "attached mass" leads to the decrease of split ring resonant frequency.

Periodically arranged split rings embedded in a porous layer are modelled after that. Scattering coefficients of the split rings are derived by replacing them with hollow fluid cylinders with "effective" properties. The latter depend on the orientation of the resonator opening relative to the rigid wall. Absorption coefficient of the porous layer with embedded scatterers is then calculated and compared with numerical model predictions and measurements.