Physical Acoustics
Ultrasonic imaging of materials and biological matter – Spatial control of sound propagation with metamaterials
Department presentation and research
The APY department's research concerns the propagation of ultrasound over a very broad spectrum of frequencies, characteristic sizes, and types of support media. The main fields of application are the control and health monitoring of industrial materials and structures (materials and assembly in the transport and energy sectors), as well as quantitative ultrasonic imaging of living matter (single biological objects). APY also develops acoustic metamaterials for the spatial control of sound in dense media via extreme acoustic properties (ultra absorption, focusing).
A general approach of the team is to understand the processes of wave-matter interactions associated with the development of advanced experimental techniques. These activities combining propagation theory, numerical simulations and experimental physics allow the creation of inverse problems giving access to new quantitative information on the local mechanical properties of the inspected media (elasticity, anisotropy, adhesion, defects), as well as the design and making of new functional composites for acoustics.
Most of these activities are approached from the point of view of multidisciplinarity in partnership with laboratories in the fields of biology, physico-chemistry and applied mathematics. This fundamental research extends into the societal world through direct contracts or partnership actions with research centers of major industrial groups.
APY activities are grouped around 3 teams (Research Operation):
- GT1 – Ultrasound-Materials (UM) focuses on Non-Destructive Evaluation (NDE) of composites, Health Monitoring of bounded structures (SHM), Non Destructive Testing (NDT) and defaults imaging (cracks, holes, delaminations). UM develops air-borne ultrasonics, non-linear ultrasonic techniques and thermo-acoustic techniques for a frequency range about the MHz.
- GT2 – Opto-Acoustics (OA) focuses on nano-transduction and imaging at very small scales (10 µm - 100 nm) by ultra-high frequency ultrasounds (GHz-sub-THz) generated and detected by optical methods.
- GT3 – Functional Materials for Acoustics (FAMAS) focuses on propagation in artificial composite media (periodic, random, locally resonant, spatially graded), for the design and making of metamaterials with functions of spatial field-control for ultrasonic instrumentation and stealth in underwater acoustics.
GT1 : Ultrasound-Materials (UM)
Referee :
Michel CASTAINGS
Members :
Christophe BACON – Stéphane BASTE – Christine BIATEAU – Michel CASTAINGS – Marc DESCHAMPS – Éric DUCASSE – Anissa MEZIANE – Mathieu RÉNIER – Samuel RODRIGUEZ
The Ultrasound-Materials team activities are centered on the non-destructive evaluation of mechanical properties of materials, and on the detection, location and imaging of discontinuities at the micro- and macro-scale.
These works are motivated by industrial needs and rely on fundamental researches on the interaction between ultrasounds and complex structures. The developed ultrasonic methods concern for instance:
- composite materials characterization under load or not;
- adhesive bond testing;
- defect detection, location and imaging (such as delamination, open or closed cracks, corrosion).
The wave propagation in heterogeneous, anisotropic, viscoelastic, linear and nonlinear materials and its diffraction by discontinuities are studied with analytical and numerical models. The thermo-elastic behavior of materials is also investigated to extend the characterization capabilities of materials.
Air-coupled ultrasonic transducers have been developed in the team and allow contactless inspection of materials.
Keywords: ultrasound propagation, complex media, anisotropy, heterogeneity, viscoelasticity, diffraction, imaging, modeling, numerical simulation, composite, defect, damage, experiments, air coupling transducers, NDE, SHM, characterization.
SHM for the non-destructive inspection of an adhesive bond between a metallic stiffener and a composite panel
GT2 : Opto-Acoustics (OA)
Referee :
Bertrand AUDOIN
Members :
Bertrand AUDOIN – Yannick GUILLET – Marie-Fraise PONGE – Clément ROSSIGNOL
The production of audible sound with the focusing and modulation of sunlight has been demonstrated since the 19th century. The modern application of this idea relies on the development of controllable coherent light sources such as lasers. Higher frequency acoustic waves propagating in solids or liquids, namely ultrasounds, could then be generated and detected at a distance without any contact to the specimen.
Laser opto-acoustics is thus a field where acoustic waves, potentially of extremely high frequencies (up to THz), are both generated and detected with short lasers pulses (fs). The team has been developing researches on the opto-acoustic transduction and on the acousto-optic detection relevant with acoustic propagation in viscoelastic materials or materials with anisotropy. The opto-acoustics of thin layers or fibres has been under the scope of their interest. Recent researches are focused on the dynamic response of single nanoparticles, and on the laser opto-acoustic elastography of single biological cells.
The group has notably demonstrated that the picosecond opto-acoustic technique in a reflectometry configuration is suitable to optically generate and detect hypersonic waves in the volume of a single sub-micronic gold particle and in the surrounding matrix. The very high frequencies involved in the acoustic spectra of nano-particles are extremely promising for imaging micrometric to nanometric structures.
In parallel, the team has demonstrated the suitability of the picosecond opto-acoustic technique for hypersound generation and detection in single biological cells. Exciting abilities for the non-invasive study of a cell and of organelles have been reported. These abilities developed in nano-phononics, based on the diffraction of optically generated acoustic pulses with nm wavelength, contribute to the development of innovative multi-physics imaging processes.
(a) Optical probing of the dynamics of a single particle and (b) optical ultrasonography of a single cell cytoskeleton
GT3 : Functional Materials for Acoustics (FAMAS)
Referee :
Olivier PONCELET
Members :
Christophe ARISTÉGUI – Thomas BRUNET – Olivier PONCELET – Alexander SHUVALOV
The FAMAS team develops theoretical, modeling and experimental activities on the propagation of waves in heterogeneous media. The research aims to analyze and understand the physical processes involved in the wave-matter interaction in random and periodic media, and to participate in the development (design and making) of new composite materials for spatial control of waves (metamaterials).
The main topics covered by this research are:
- the effective media allowing modeling of wave propagation at the macroscopic scale in heterogeneous media (definition of homogeneous equivalent dispersive properties such as dynamic mass density and dynamic elasticity constants, generalized elasto-inertial constitutive laws). Heterogeneous media may be random or structured (elastic or piezo-active phononic crystals);
- the design and making of metamaterials by means of soft-matter technics in collaboration with physico-chemistry Labs of the Bordeaux campus. The developed materials contain resonant inclusions whose response drastically affects the macroscopic properties of waves (ultra absorption, negative phase velocity, zero wavenumber, very slow waves, etc.). Potentially associated with spatial gradients, these extreme acoustic properties allow the manipulation of acoustic fields to focus, collimate, steer beams, or else to create acoustic screens and super absorbers;
- mathematical techniques for wave-field calculation in periodic media (stability, speed, accuracy).
This fundamental research is mainly financed by public programs (ANR, IdEx) but takes more and more part of a techno-industrial panorama looking for new materials with specific and non-standard acoustic properties (naval domain in particular)..
Contact :
Olivier PONCELET
Responsable de Dpt
Université de Bordeaux
351 Cours de la Libération
33405 TALENCE CEDEX
05 40 00 21 91
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