Acoustic, elastic and thermal metamaterials IV

10:30 : Seismic holes for controlling surface waves

Stephane Brule (1),Sebastien Guenneau (2),Stefan Enoch (2)

(1)Menard Soletanche-Freyssinet Group Vinci (France) , (2)Institut Fresnel (France)

The concept of controlling seismic waves is in progress and first full-scale experiments had confirmed the interest which we can have for this new axis of research. Here we show the dynamic response of a meter-scale grid of vertical empty cylindrical holes, under the excitation of a 50 hz source.
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10:45 : Numerical analysis of spherical cloaks with symmetric and asymmetric elasticity tensors.

Andre Diatta, S. Guenneau

Institut Fresnel (France)

We present some general framework for elastodynamic cloaking, with an emphasis on a markedly enhanced control of solid waves in heterogeneous anisotropic media. Potential applications are in seismic wave protection by detouring coupled pressure and shear waves around a region one would like to protect. We give a brief review on spherical elastodynamic cloaks with a rank-4, asymmetric, elasticity tensor. We also discuss the importance of geometric transforms in the design of perfectly matched elastic layers.
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11:00 : Experimental demonstration of ordered and disordered multi-resonant metamaterials for Lamb waves

Matthieu Rupin (1),Fabrice Lemoult (1),Geoffroy Lerosey (1),Philippe Roux (2)

(1)ESPCI ParisTech (France) , (2)Institut des Sciences de la Terre (France)

We demonstrate the experimental realization of a multi-resonant metamaterial for Lamb waves, i.e. elastic waves propagating in plates. The metamaterial effect comes from the resonances of long aluminum rods that are attached to an aluminum plate. Using time-dependent measurements, we experimentally prove that such a medium exhibits wide band gaps as well as sub- and supra-wavelength modes for both a periodic and a random arrangement of the resonators.
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11:15 : Opto-Mechanical Interactions in Split Ball Resonators

Yue Sun, Sergey V. Suchkov, Andrey E. Miroshnichenko, Andrey A. Sukhorukov

Australian National University (Australia)

We demonstrate that a gold split-ball resonator in the form of a spherical nanoparticle with a cut supports optical magnetic and acoustic modes, which are strongly co-localized near the cut, enabling strong opto-mechanical interactions. We simulate the excitation of the acoustic vibrations through laser heating and optical forces induced by the optical magnetic resonance, and determine that a laser pulse which gives 100K temperature change yields acoustic oscillations resulting in 10 percent modification of the optical scattering.
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11:30 : Fick's second law transformed: one path to cloaking in mass diffusion

Tania Puvirajesinghe (1),S. Guenneau (2)

(1)CRCM - Inserm (France) , (2)Institut Paoli-Calmettes (France)

We have adapted the concept of transformational thermodynamics, for the diffusion and transport of mass concentration. We initially used finite-element computations to model liposome particles surrounded by a cylindrical multi-layered cloak in a water-based environment [1]. Independent research groups have applied our model to applications implicating the protection of steel [2] as well as for the design of water-based invisibility cloaks [3]. We now investigate the utility of the biocloak for vectorization of drugs [4].
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11:45 : Use of metamaterials and transformation thermodynamics for the manipulation of mass flow in engineering systems

Juan Restrepo-Florez, Martin Maldovan

Georgia Institue of Technology (USA)

In this work, the use of transformation thermodynamic techniques is applied for the design of a mass flux concentrator. We study the effect of different design parameters (number of layers and volume fraction of the materials) on the performance of the device, the objective of this work is to extend the ideas of optical and thermal metamaterials to mass-transfer manipulation devices.
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12:00 : Negative Refraction of Lamb Waves

Benoit Gerardin (1),Jerome Laurent (2),Claire Prada (1),Alexandre Aubry (1)

(1)ESPCI ParisTech (France) , (2)Institut Langevin (France)

Negative index materials have received considerable attention in recent years since they offer many potential applications to manipulate waves in unusual ways. Here we present theoretical, numerical and experimental results on several simple devices based on negative refraction.
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12:15 : Experiments on gradient-index lenses in elastic plates

Patrick Sebbah (1),G. Lefebvre (1),M. Dubois (1),R. Beauvais (1),Y. Achaoui (2),R. Ing (1),S. Guenneau (2)

(1)Institut Langevin - ESPCI (France) , (2)Institut Fresnel (France)

We investigate the possibility to design gradient-index lenses for flexural waves propagating in thin plates. We experimentally explore the dynamics of an elastic plate whose thickness varies radially. We design the right thickness profile to form the equivalent in elastodynamics of the Maxwell's fisheye lens in optics. Its imaging properties for a Gaussian pulse are very similar to those predicted by ray trajectories (great circles) on a virtual sphere.
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