Publications
295 results found
Ungureanu B, Makwana MP, Craster RV, et al., 2022, Elastic body waves control via the Topological Rainbow Effect, Pages: 599-600
We propose a form of topological guidance for flexural waves in thin perforated elastic plates [1], which can be viewed as an approximate model for surface Rayleigh waves propagating through an array of boreholes drilled in soft soil atop bedrock. We do so by considering a square perforation within a square unit cell that is then extended periodically upon a square lattice, as illustrated in figure 1, when combined with the rainbow effect, offers a pragmatic route to energy harvesting.
Chatzopoulos Z, Palermo A, Diatta A, et al., 2022, Cloaking for surface elastic waves, Pages: X101-X103
We design a cloak for surface Rayleigh and Love waves. To such purpose we utilize the invariance of the Navier elastodynamic equation under geometric transform by assuming identical displacements in original and transformed media (Cosserat gauge). In particular, we apply transformation elastodynamics to obtain the requisite mechanical properties for a 3-D cylindrical carpet cloak with a triangular cross section. Dispersion analysis and time-harmonic simulations are conducted to validate the performance of the cloak characterized by an elasticity tensor without the minor symmetries (Cosserat medium). Finally, symmetrization techniques of the elasticity tensor are applied in order to approximate the anisotropic and chiral properties of the cloak with isotropic Cauchy materials.
Huidobro et al, 2021, Correction for Huidobro et al., Fresnel drag in space–time-modulated metamaterials, Proceedings of the National Academy of Sciences, Vol: 118, Pages: 1-1, ISSN: 0027-8424
Marigo JJ, Pham K, Maurel A, et al., 2021, Effective Model for Elastic Waves in a Substrate Supporting an Array of Plates/Beams with Flexural and Longitudinal Resonances, Journal of Elasticity, Vol: 146, Pages: 143-177, ISSN: 0374-3535
In a previous study (Marigo et al. in J. Mech. Phys. Solids 143:104029, 2020) we have studied the effect of a periodic array of subwavelength plates or beams over a semi-infinite elastic ground on the propagation of waves hitting the interface. The study was restricted to the low frequency regime where only flexural resonances take place. Here, we present a generalization to higher frequencies which allows us to account for both flexural and longitudinal resonances and to evaluate their interplay. An effective model is obtained using asymptotic analysis and homogenization techniques, which can be expressed in terms of the ground alone with an effective dynamic (frequency-dependent) boundary conditions of the Robin’s type. For an in-plane wave at oblique incidence, the scattered displacement fields and the reflection coefficients are obtained in closed forms and their effectiveness to reproduce the actual scattering is inspected by comparison with direct numerics in a two-dimensional setting.
Farhat M, Guenneau S, Chen P-Y, et al., 2021, Spacetime modulation in floating thin elastic plates, PHYSICAL REVIEW B, Vol: 104, ISSN: 2469-9950
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- Citations: 3
Meng Y, Hao Y, Guenneau S, et al., 2021, Willis coupling in water waves, NEW JOURNAL OF PHYSICS, Vol: 23, ISSN: 1367-2630
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- Citations: 12
Farhat M, Guenneau S, Chen P-Y, et al., 2021, Reply to "Comment on 'Scattering Cancellation-Based Cloaking for the Maxwell-Cattaneo Heat Waves'", PHYSICAL REVIEW APPLIED, Vol: 15, ISSN: 2331-7019
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- Citations: 1
Cassier M, DeGiovanni T, Guenneau S, et al., 2021, Active thermal cloaking and mimicking, PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 477, ISSN: 1364-5021
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- Citations: 5
Makwana MP, Chaplain GJ, 2021, Acoustic topological circuitry in square and rectangular phononic crystals, Physical Review Applied, Vol: 15, Pages: 1-13, ISSN: 2331-7019
We use square and rectangular phononic crystals to create experimental realizations of complex topological phononic circuits. The exotic topological transport observed is wholly reliant upon the underlying structure that must belong to either a square or rectangular lattice system and not to any hexagonal-based structure. The phononic system we use consists of a periodic array of square steel bars that partitions acoustic waves in water over a broadband range of frequencies (about 0.5 MHz). An ultrasonic transducer launches an acoustic pulse that propagates along a domain wall, before encountering a nodal point, from which the acoustic signal partitions towards three exit ports. Numerical simulations are performed to clearly illustrate the highly resolved edge states as well as corroborate our experimental findings. To achieve complete control over the flow of energy, we need to create power division and redirection devices. The tunability afforded by our designs, in conjunction with the topological robustness of the modes, will lead to incorporation into acoustical devices.
Guenneau S, Lombard B, Bellis C, 2021, Time-domain investigation of an external cloak for antiplane elastic waves, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951
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- Citations: 5
Farhat M, Chen P-Y, Guenneau S, et al., 2021, Self-dual singularity through lasing and antilasing in thin elastic plates, PHYSICAL REVIEW B, Vol: 103, ISSN: 2469-9950
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- Citations: 15
Ji Q, Chen X, Liang J, et al., 2021, Designing thermal energy harvesting devices with natural materials through optimized microstructures, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 169, ISSN: 0017-9310
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- Citations: 20
Tang K, Xu C, Guenneau S, et al., 2021, Pulse Dynamics of Flexural Waves in Transformed Plates, ADVANCED FUNCTIONAL MATERIALS, Vol: 31, ISSN: 1616-301X
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- Citations: 4
Gralak B, Guenneau S, 2021, Foreword, Comptes Rendus Physique, Vol: 21, Pages: 619-623, ISSN: 1631-0705
Brûlé S, Guenneau S, 2021, Past, present and future of seismic metamaterials: Experiments on soil dynamics, cloaking, large scale analogue computer and space–time modulations, Comptes Rendus Physique, Vol: 21, Pages: 767-785, ISSN: 1631-0705
Some properties of electromagnetic metamaterials have been translated, using some wave analogies, to surface seismic wave control in sedimentary soils structured at the meter scale. Two large scale experiments performed in 2012 near the French cities of Grenoble [1] and Lyon [2] have confirmed the usefulness of this methodology and its potential influence on soil-structure interaction. We present here a new perspective on the in-situ experiment near Lyon, which unveils energy corridors in the seismic lens. We further introduce a concept of time-modulated seismic metamaterial underpined by an effective model based on Willis’s equations. As a first application, we propose that ambient seismic noise time-modulates structured soils that can be viewed as moving media. In the same spirit, a design of an analogous seismic computer is proposed making use of ambient seismic noise. We recall that ancient Roman theaters and forests of trees are two examples of large scale structures that behave in a way similar to electromagnetic metamaterials: invisibility cloaks and rainbows, respectively. Seismic metamaterials can thus not only be implemented for shielding, lensing and cloaking of potentially deleterious Rayleigh waves, but they also have potential applications in energy harvesting and analogous computations using ambient seismic noise, and this opens new vistas in seismic energy harvesting and conversion through the use of natural or artificial soil structuring.
Gralak B, Guenneau S, 2021, Foreword, Comptes Rendus Physique, Vol: 21, Pages: 311-341, ISSN: 1631-0705
Fu S, Li G, Craster R, et al., 2021, Wavelet-based Edge Multiscale Finite Element Method for Helmholtz problems in perforated domains, Multiscale Modeling & Simulation, Vol: 19, Pages: 1684-1709, ISSN: 1540-3459
Craster R, Diatta A, Guenneau S, et al., 2021, On near-cloaking for linear elasticity, Multiscale Modeling & Simulation, Vol: 19, Pages: 633-664, ISSN: 1540-3459
We make precise some results on the cloaking of displacement fields in linear elasticity. In the spirit of transformation media theory, the transformed governing equations in Cosseratand Willis frameworks are shown to be equivalent to certain high-contrast small defect problems forthe usual Navier equations. We discuss near-cloaking for elasticity systems via a regularized transform and perform numerical experiments to illustrate our near-cloaking results. We also study thesharpness of the estimates from [H. Ammari, H. Kang, K. Kim, and H. Lee, J. Differential Equations,254 (2013), pp. 4446--4464], wherein the convergence of the solutions to the transmission problems isinvestigated, when the Lam\'e parameters in the inclusion tend to extreme values. Both soft and hardinclusion limits are studied and we also touch upon the finite frequency case. Finally, we propose anapproximate isotropic cloak algorithm for a symmetrized Cosserat cloak.
Ungureanu B, Tournat V, Craster R, et al., 2021, Theory and experiments for seismic waves propagating within an array of clamped inclusions in a soft matrix, 15th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), Publisher: IEEE, Pages: X438-X441
Makwana M, Wiltshaw R, Craster R, et al., 2021, Topological guidance in novel photonic crystal fibers, 15th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), Publisher: IEEE, Pages: X144-X147
Farhat M, Guenneau S, Chen P-Y, et al., 2020, Parity-Time Symmetry and Exceptional Points for Flexural-Gravity Waves in Buoyant Thin-Plates, CRYSTALS, Vol: 10
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- Citations: 3
Makwana M, Wiltshaw R, Guenneau S, et al., 2020, Hybrid topological guiding mechanisms for photonic crystal fibers, Optics Express, Vol: 28, Pages: 30871-30888, ISSN: 1094-4087
We create hybrid topological-photonic localisation of light by introducing concepts from the field of topological matter to that of photonic crystal fiber arrays. S-polarized obliquely propagating electromagnetic waves are guided by hexagonal, and square, lattice topological systems along an array of infinitely conducting fibers. The theory utilises perfectly periodic arrays that, in frequency space, have gapped Dirac cones producing band gaps demarcated by pronounced valleys locally imbued with a nonzero local topological quantity. These broken symmetry-induced stop-bands allow for localised guidance of electromagnetic edge-waves along the crystal fiber axis. Finite element simulations, complemented by asymptotic techniques, demonstrate the effectiveness of the proposed designs for localising energy in finite arrays in a robust manner.
Marigo JJ, Pham K, Maurel A, et al., 2020, Effective model for elastic waves propagating in a substrate supporting a dense array of plates/beams with flexural resonances, Journal of the Mechanics and Physics of Solids, Vol: 143, ISSN: 0022-5096
We consider the effect of an array of plates or beams over a semi-infinite elastic ground on the propagation of elastic waves hitting the interface. The plates/beams are slender bodies with flexural resonances at low frequencies able to perturb significantly the propagation of waves in the ground. An effective model is obtained using asymptotic analysis and homogenization techniques, which can be expressed in terms of the ground alone with effective dynamic (frequency-dependent) boundary conditions of the Robin's type. For an incident plane wave at oblique incidence, the displacement fields and the reflection coefficients are obtained in closed forms and their validity is inspected by comparison with direct numerics in a two-dimensional setting.
Guenneau S, Zolla F, Cherkaev E, et al., 2020, Multiple scale method applied to homogenization of irrational metamaterials, Pages: 162-164
We adapt the multiple scale method introduced over 40 years ago for the homogenization of periodic structures [1], to the quasiperiodic (cut-and-projection) setting. We make use of partial differential operators (gradient, divergence and curl) acting on periodic functions of m variables in a higher-dimensional space that are projected onto operators acting on quasiperiodic functions in the n-dimensional physical space (mn). We replace heterogeneous quasiperiodic structures, coined irrational metamaterials in [2], by homogeneous media with anisotropic permittivity and permeability tensors, obtained from the solution of annex problems of electrostatic type in a periodic cell in higher dimensional space. This approach is valid when the wavelength is much larger than the period of the higher dimensional elementary cell.
Varma TV, Ungureanu B, Sarkar S, et al., 2020, The influence of structure geometry and material on seismic metamaterial performance, Publisher: arXiv
Diverting, and controlling, elastic vibrations impacting upon infrastructureis a major challenge for seismic hazard mitigation, and for the reduction ofmachine noise and vehicle vibration in the urban environment. Seismicmetamaterials (SMs), with their inherent ability to manipulate wavepropagation, provide a key route for overcoming the technological hurdlesinvolved in this challenge. Engineering the structure of the SM serves as abasis to tune and enhance its functionality, and inspired by split rings,swiss-rolls, notch-shaped and labyrinthine designs of elementary cells inelectromagnetic and mechanical metamaterials, we investigate altering thestructure geometries of SMs with the aim of creating large bandgaps\textcolor{black}{in a subwavelength regime}. We show that square stiffinclusions, perform better in comparison to circular ones, whilst keeping thesame filling fraction. En route to enhancing the bandgap, we have also studiedthe performance of SMs with different constituent materials; we find that steelcolumns, as inclusions, show large bandgaps, however, the columns are too largefor steel to be a feasible material in practical or financial terms.Non-reinforced concrete would be preferable for industry level scaling up ofthe technology because, concrete is cost-effective, easy to cast directly atthe construction site and easy to provide arbitrary geometry of the structure.As a part of this study, we show that concrete columns can also be designed toexhibit bandgaps if we cast them within a soft soil coating surrounding theprotected area for various civil structures like a bridge, building, oilpipelines etc.
Chen Y, Kadic M, Guenneau S, et al., 2020, Isotropic Chiral Acoustic Phonons in 3D Quasicrystalline Metamaterials, PHYSICAL REVIEW LETTERS, Vol: 124, ISSN: 0031-9007
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- Citations: 19
Farhat M, Guenneau S, Alu A, et al., 2020, Scattering cancellation technique for acoustic spinning objects, PHYSICAL REVIEW B, Vol: 101, ISSN: 2469-9950
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- Citations: 14
Makwana M, Laforge N, Craster R, et al., 2020, Experimental observations of topologically guided water waves within non-hexagonal structures, Applied Physics Letters, Vol: 116, Pages: 131603-1-131603-5, ISSN: 0003-6951
We investigate symmetry-protected topological water waves within a strategically engineered square lattice system. Thus far, symmetry-protected topological modes in hexagonal systems have primarily been studied in electromagnetism and acoustics, i.e. dispersionless media. Herein, we show experimentally how crucial geometrical properties of square structures allow for topological transport that is ordinarily forbidden within conventional hexagonal structures. We perform numerical simulations that take into account the inherent dispersion within water waves and devise a topological insulator that supports symmetry-protected transport along the domain walls. Our measurements, viewed with a high-speed camera under stroboscopic illumination, unambiguously demonstrate the valley-locked transport of water waves within a non-hexagonal structure. Due to the tunability of the energy's directionality by geometry, our results could be used for developing highly-efficient energy harvesters, filters and beam-splitters within dispersive media.
Pham K, Maurel A, Félix S, et al., 2020, Hybridized love waves in a guiding layer supporting an array of plates with decorative endings, Materials, Vol: 13, Pages: 1-27
This study follows from Maurel et al., Phys. Rev. B 98, 134311 (2018), where we reported on direct numerical observations of out-of-plane shear surface waves propagating along an array of plates atop a guiding layer, as a model for a forest of trees. We derived closed form dispersion relations using the homogenization procedure and investigated the effect of heterogeneities at the top of the plates (the foliage of trees). Here, we extend the study to the derivation of a homogenized model accounting for heterogeneities at both endings of the plates. The derivation is presented in the time domain, which allows for an energetic analysis of the effective problem. The effect of these heterogeneous endings on the properties of the surface waves is inspected for hard heterogeneities. It is shown that top heterogeneities affect the resonances of the plates, hence modifying the cut-off frequencies of a wave mathematically similar to the so-called Spoof Plasmon Polariton (SPP) wave, while the bottom heterogeneities affect the behavior of the layer, hence modifying the dispersion relation of the Love waves. The complete system simply mixes these two ingredients, resulting in hybrid surface waves accurately described by our model.
Chen Y, Frenzel T, Guenneau S, et al., 2020, Mapping acoustical activity in 3D chiral mechanical metamaterials onto micropolar continuum elasticity, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 137, ISSN: 0022-5096
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- Citations: 44
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