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Logo Laboratoire d'Acoustique de l'Université du Mans
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Materials

Materials

Materials

This team conducts research on acoustic propagation in complex media (metamaterials, phonic crystals, granular, inhomogeneous, nonlinear, porous,...). The work carried out focuses on fundamental aspects: wave-material interactions (nonlinear acoustics, study of energy transfers, couplings, damage, wave control, resolution of inverse problems, signal processing,...).

This work also extends to applications such as property identification, imaging, implementation of diagnostic tools, sound absorption, wave control, non-destructive evaluation and control).

Acoustics and Mechanics of Porous Materials

This research operation studies the acoustic and mechanical properties of porous and metaporous materials used in various acoustic applications. It includes different topics of study: anisotropic porous materials with gradient properties, numerical methods for porous and metaporous, experimental characterization methods, (e.g. SLATCoW method, Spatial LAplace Transform for Complex Wavenumber recovery), phononic crystals and hyperuniform media, plates/zero density and doping, critical coupling, slow wave and perfect absorption, metadiffusers and thin structures for sound diffusion, nonlocal acoustic description of properties inspired by nonlocal electromagnetism.  

SLATCoW method :  (Geslain et al., J. Appl. Phys. 120: 135107, (2016))SLATCoW method : (Geslain et al., J. Appl. Phys. 120: 135107, (2016))

 

Metasurfaces : (N Jiménez, TJ Cox, V Romero-García, JP Groby, Metadiffusers: Deep-subwavelength sound diffusers,  Sci. Rep. 7: 5389, (2017))

Metasurfaces : (N Jiménez, TJ Cox, V Romero-García, JP Groby, Metadiffusers: Deep-subwavelength sound diffusers, Sci. Rep. 7: 5389, (2017))

Acoustics of Granular Media

Topological Mechanics and Nonlinearity

Although first related to electrons, the fast-developing field of topological insulators has spurred the relevant research also in classical settings, for example, in acoustics and mechanics. This revealed a plethora of classical wave setups with robust localization and transfer of sound -- potentially offering novel applications in energy harvesting, vibration isolation, and phononic waveguiding.

 

Using simple one and two-dimensional, topological, mechanical lattices, we are trying to reveal and understand intriguing topological, phenomena, such as disorder- and amplitude-dependent topological transitions, non-adiabatic transfer of topological states, and the existence and stability of nonlinear edge and gap solitons.

Fig .1 (a)Fig .1 (a)

Fig .1 (a) Topologically nontrivial and (b) trivial interface mode in a mechanical granular graphene, (c-e) stable nonlinear topologically nontrivial edge mode

 

Fig .1 (a) Topologically nontrivial and (b) trivial interface mode in a mechanical granular graphene, (c-e) stable nonlinear topologically nontrivial edge mode

 

 

 

 

Nonlinear Flexible Elastic Metamaterials

Flexible elastic metamaterials (flexEM) can be defined as artificial, architected structures possessing the ability to deform substantially, repeatedly and reversibly. In recent years, flexEM have undergone rapid developments in their uses and applications, like in the context of soft robotics, innovative actuation (locomotion, grasping), mechanical switching and precise motion control,  or large-scale reconfiguration.

Among all the possible flexEM designs, we are interested in the one composed of rotating masses, such as those shown in Fig. 2. 

Among all the possible flexEM designs, we are interested in the one composed of rotating masses, such as those shown in Fig. 2. 

 

 

Indeed, the coexistence of two/three degrees of freedom per site (translations and rotations) and the strong geometrical non-linearity originating from the large rotations, give rise to novel nonlinear phenomena in such architectures, such as vector elastic pulse solitons and transition waves. The latter have in particular proven their interest in the macroscopic reconfiguration of a bistable flexEM.

Opto-Acoustics & Laser Ultrasound

Research in opto-acoustics aims to introduce innovative methods for the generation and detection of acoustic waves by lasers for the acoustic evaluation and non-destructive testing of materials and structures.

Here, the role played by the piezoelectric transducer in traditional ultrasonic measurements is attributed to a laser, but the latter can play this role remotely and without any contact with the materials. If necessary, the excitation and detection of sound can be very local (down to the micron scale, diameter of the focused laser beam) or, on the contrary, can quickly and optically scan large areas (up to a few meters).

Opto-acoustics, in addition to other frequency ranges accessible by traditional methods, gives access to hypersonic frequencies of acoustic waves (above 1 GHz). In particular, acoustic waves with frequencies above 10 GHz have wavelengths shorter than the micrometer in solids. This makes laser-generated and detected hypersonic sound a unique tool for the non-destructive evaluation of nanocrystalline materials and nanostructures, as well as for three-dimensional imaging inside continuously inhomogeneous media with nanometers scale axial resolution.

The non-contact nature of this technique makes it particularly suitable for the evaluation of materials in hostile environments, such as very high temperatures and/or very high pressures, making it a very interesting control tool for both fundamental research and industrial applications.

Ultrasounds

This research operation is mainly oriented, through both fundamental and applied approaches, towards the
and applied approaches, towards the development of ultrasonic methods for the evaluation and
non-destructive testing (NDT) of materials. The research activities aim at contributing to
a better understanding of the linear and non-linear interactions between ultrasonic waves
and complex solids, bringing together different approaches implemented on the theoretical and experimental levels
theoretical and experimental levels :

  •  Ultrasonic waves and guided waves in solids and biological media,
  • Acoustic emission for the characterization of structural materials,
  • Non-linear acoustics and interferometry by CODA waves for ECND,
  • Mechanical solicitation for the characterization of composite materials.

This OR includes 10 permanent researchers. In 2020, 10 PhD students are working in this OR (15 theses have been defended since 2015). This OR also has certain specificities : (i) the permanent researchers involved are spread over different sites (UFR S&T, ENSIM, IUT, ESEO and CTTM), (ii) the proposed approaches are diverse both in the methods used and in the materials applied. Finally, it is important to note the federative character of the ECND theme at the LAUM, which involves to various degrees the participation of 9 other colleagues in the work carried out here. At the national level, in addition to its academic collaborations (for example the laboratories of the ECND-PdL project and of FANO), the OR ULTRASOUNDS has strong industrial collaborations. At the regional level, the collective emergence project "ECND-PdL has allowed to reinforce the federative character of the ECND theme and has resulted in the creation of the GIS ECND-PDL (https://ecnd-pdl.fr/) in 2018.

Themes pursued in the OR

Non-destructive testing of roughness by modal wave decoherence, characterization of of rough plates by SH waves.

Non-destructive testing of roughness by modal wave decoherence, characterization of of rough plates by SH waves.


Acoustic emission and parsimonious representations for the monitoring of damage to multi-layer materials.

Acoustic emission and parsimonious representations for the monitoring of damage to multi-layer materials.


CND and Gradient Property Materials

CND and Gradient Property Materials

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