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Dirac cones and chiral selection of elastic waves in a soft strip

Abstract : Significance We monitor the propagation of in-plane elastic waves in an incompressible thin strip and observe a Dirac cone in a soft material. Additional remarkable wave features such as negative phase velocities, pseudo-zero group velocity, and one-way chiral selection are highlighted. These results are universal: Any thin strip made of any soft elastomer will display the same behavior. Dirac cones have inspired many developments in the condensed-matter field over the last decade. Our findings enable the search for analogs in the realm of soft matter, leading to a wide range of potential applications. Additionally, they are of practical interest for biologists since soft strips are ubiquitous among human tissues and organs. Abstract We study the propagation of in-plane elastic waves in a soft thin strip, a specific geometrical and mechanical hybrid framework which we expect to exhibit a Dirac-like cone. We separate the low frequencies guided modes (typically 100 Hz for a 1-cm-wide strip) and obtain experimentally the full dispersion diagram. Dirac cones are evidenced together with other remarkable wave phenomena such as negative wave velocity or pseudo-zero group velocity (ZGV). Our measurements are convincingly supported by a model (and numerical simulation) for both Neumann and Dirichlet boundary conditions. Finally, we perform one-way chiral selection by carefully setting the source position and polarization. Therefore, we show that soft materials support atypical wave-based phenomena, which is all of the more interesting as they make most of the biological tissues.
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Contributor : Gestionnaire Hal-Su <>
Submitted on : Thursday, November 19, 2020 - 12:28:32 PM
Last modification on : Tuesday, December 8, 2020 - 3:34:22 AM
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Maxime Lanoy, Fabrice Lemoult, Antonin Eddi, Claire Prada. Dirac cones and chiral selection of elastic waves in a soft strip. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2020, pp.202010812. ⟨10.1073/pnas.2010812117⟩. ⟨hal-03014230⟩



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