Matériaux, résonances et interfaces (MRI)

Responsable

Sébastien BIDAULT

Tél. : 01 80 96 30 49

Co-responsable

Valentina KRACHMALNICOFF

Tél. : 01 80 96 30 73

Membres permanents

Sébastien BIDAULT

Tél. : 01 80 96 30 49

Yannick DE WILDE

Tél. : 01 80 96 30 84

Samuel GRESILLON

Tél. : 01 80 96 30 37

Xiaoping JIA

Tél. : 01 80 96 30 43

Valentina KRACHMALNICOFF

Tél. : 01 80 96 30 73

Fabrice LEMOULT

Tél. : 01 80 96 30 50

Anne LOUCHET-CHAUVET

Tél. : 01 80 96 30 42

Sylvain MEZIL

Tél. : 01 80 94 30 94

Claire PRADA

Tél. : 01 80 96 30 53

Arnaud TOURIN

Tél. : 01 80 96 30 63

Actualités

Exploring the limits to quantitative elastography: supersonic shear imaging in stretched soft strips Croquette, S., A. Delory, D. A. Kiefer, C. Prada, and F. Lemoult Physics in Medicine and Biology 70, no. 14 (2025) Résumé: Objective. Shear wave elastography has enriched ultrasound medical imaging with quantitative tissue stiffness measurements. We aim to explore the limitations that persist related to viscoelasticity, guiding geometry or static deformation. Approach. A nearly-incompressible soft elastomer strip is chosen to mimic the mechanical behaviour of an elongated tissue. A supersonic shear wave scanner measures the propagation of shear waves within the strip. It provides a wide range of shear wave velocities, from 2 to 6 m s<sup>−1</sup>, depending on the frequency, the static strain as well as the orientation of the strip. Main results. To explain these different measurements, the guided wave effect is highlighted and analysed from the dispersion diagrams provided by the spatio-temporal Fourier transform of the raw data. The guided waves are then described using a material model that accounts for both the rheology and the hyperelastic behaviour, and allows to extract the mechanical parameters of the sample. Significance. To overcome some limitations of current elastography, we propose a theoretical framework which allows the simultaneous characterization of the viscoelastic and hyperelastic properties of soft tissues, paving the way for robust quantitative elastography of elongated tissues.
Influence of Normal Stress, Shear Velocity and Materials on Steady-State Shear Resistance and Viscosity of Rapid Dry Granular Flows Hu, W., Y. Li, H. Gou, X. Jia, L. Zhou, and C. Chang Journal of Geophysical Research Solid Earth 130, no. 6 (2025) Résumé: Understanding the rheological behavior of rapid granular flows is crucial for understanding various geological processes, such as fast fault slip and rapid motion of landslides. In this study, we conducted rotary shear experiments on different granular materials, spanning a range of shear velocities from slow to rapid and under varying normal stresses, to investigate the evolution of mechanical behavior under different flow conditions. The experimental results showed that steady-state shear resistance varied with normal stress and material composition at shear velocities below 1 m/s. A consistent velocity-dependent trend was observed. The steady-state shear resistance of the sample experienced a transition from velocity-strengthening behavior at low shear velocities (below 0.1 m/s) to velocity-weakening behavior at higher shear velocities (above 0.1 m/s). Interestingly, at shear velocities exceeding 1 m/s, the steady-state shear resistance became independent of normal stress and material composition, converging to a similar steady-state value for both crushable and uncrushable materials. Although normal stress and mineral composition had a limited influence on steady-state shear resistance at high shear rates, they significantly affected the weakening rate (the transition from peak strength to steady-state shear resistance), which was strongly correlated with the material's crushing ability, as characterized by the Weibull modulus. These findings provide insights into the mechanisms governing the hypermobility of mega-landslides and the rapid dynamics of geological flows.
Enhanced mm-Wave Frequency Up-Conversion via a Time-Varying Graphene Aperture on a Cavity Resonator Amanatiadis, S., T. Karamanos, F. Lemoult, and N. V. Kantartzis Micromachines 16, no. 6, 679 (2025) Résumé: The transition to 5G and beyond has highlighted the need for efficient devices that operate at mm-wave frequencies, which require new structures and pose fabrication challenges. This paper proposes a novel non-linear antenna that combines the well-established substrate-integrated cavity (SIC) radiators and time-varying graphene for generating harmonic frequencies in the mm-wave spectrum. Graphene is represented as having a dispersive surface conductivity, while time modulation of the conductivity is introduced by varying the applied bias electric field. A modified FDTD algorithm is, additionally, used to simulate the time-varying graphene behaviour under different modulation schemes. The final antenna design involves an SIC resonator with a graphene-covered slot aperture for radiation. The numerical study highlights the effective generation of harmonics using the modulated graphene at the mm-wave regime. Finally, different modulation schemes are applied to enhance certain higher-order harmonics, demonstrating the potential of this non-linear antenna design for future mm-wave and THz frequency applications.
Nonmonotonic Radiative Heat Transfer in the Transition from Far Field to Near Field Guillemot, V., R. Messina, V. Krachmalnicoff, R. Carminati, P. Ben-Abdallah, W. Poirier, and Y. De Wilde Physical Review Letters 134, no. 19 (2025) Résumé: We present high precision measurements of the radiative heat transfer of a glass microsphere immersed in a thermal bath in vacuum facing three different planar substrates (SiO2, SiC, and Au), which exhibit very different optical behaviors in the infrared region. Using a thermoresistive probe on a cantilever, we show the nonmonotonic behavior of the radiative flux between the microsphere and its environment when the microsphere is brought closer to the substrate in the far-field to near-field transition regime. We demonstrate that this unexpected behavior is related to the singularities of dressed emission mechanisms in this three-body system sphere-substrate bath with respect to the separation distance.

> Toutes les publications...

Présentation du thème

Nos activités portent à la fois sur l’étude et la caractérisation de matériaux en interaction avec des ondes électromagnétiques ou mécaniques, mais aussi sur la conception de matériaux artificiels (métamatériaux) avec une ingénierie précise de leurs propriétés optiques, microondes ou acoustiques. Nous exploitons et analysons des phénomènes de résonance et de guidage des ondes aux interfaces et leur incidence sur la propagation et les relations de dispersion spectrales et spatiales.
Ceci nous amène à la conception de nouveaux matériaux actifs, dépendant du temps ou biomimétiques, et aussi au développement de dispositifs expérimentaux d’imagerie, de spectroscopie et de métrologie. Nos efforts s’inscrivent dans des domaines tels que les technologies quantiques, la nanophotonique, la nanothermique, le contrôle non-destructif et la sismologie des milieux granulaires.

Axes de recherche

Haut de page

L’Institut Langevin

Actualités

Recherche

Membres

Publications

Séminaires & écoles thématiques

Enseignement

Nous recrutons

Contact

Matériaux, résonances et interfaces (MRI)

Responsable

Co-responsable

Membres permanents

Actualités

Présentation du thème

Axes de recherche