Institut des
NanoSciences de Paris
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Soutenance de thèse de Wei Wang - Vendredi 4 octobre 2019 à 14 h

Wei Wang, doctorant dans l’équipe Acoustique pour les nanosciences, soutient sa thèse le vendredi 4 octobre 2019 à 14 h.

IMPMC - Sorbonne Université - 4 place Jussieu, 75005 Paris, tour 23, 4e étage, couloir 22-23, salle 401

Manipulation of Lamb Waves with Elastic metamaterials

Abstract

We develop elastic pillared metamaterials to manipulate Lamb waves. Firstly, the negative properties associated with bending, compression and torsion resonances in two structures consisting of pillars on one side of a thin plate are examined. We describe in details two different mechanisms at the origin of doubly negative property. The potential of these structures for negative refraction of Lamb waves and acoustic cloaking is demonstrated numerically. Secondly, we present the topologically protected transport of Lamb waves by analogy with quantum spin and valley quantum Hall effects. By rearranging the previous structures into a honeycomb network, a single Dirac cone and a double Dirac cone are introduced. We discuss the appearance of topologically valley-protected edge states in an asymmetrical double-sided pillar structure. The unidirectional propagation of edge states on different domain walls is studied. In addition, we consider a symmetrical double-sided system allowing the separation of the symmetric and antisymmetric modes. Combined edge states protected topologically by pseudospin and pseudospin-valley degree of freedom are demonstrated. Third, we propose an approach to actively control the transmission of the antisymmetric Lamb wave propagating through an infinite line of pillars. Two different situations with bending and compression resonances respectively separated or superimposed are studied. External tensile force and pressure are applied to the pillars, which allows them to couple with the bending and compressive vibrations. The transmission is studied as a function of the amplitude and the relative phase of the external sources.

Jury

  • Bruno MORVAN - Université Le Havre Normandie - Rapporteur
  • Abdelkrim TALBI - Ecole Centrale Lille - Rapporteur
  • Thomas BRUNET - Université de Bordeaux - Examinateur
  • Bahram DJAFARI-ROUHANI - Université Lille 1 - Examinateur
  • Régis MARCHIANO - Sorbonne Université - Examinateur
  • Yan PENNEC - Université Lille 1 - Examinateur
  • Bernard BONELLO - Sorbonne Université - Directeur de thèse