title: Sub-wavelength energy trapping of elastic waves in a metamaterial.
abstract: Deep sub-wavelength focusing has been demonstrated for locally resonant metamaterials using electromagnetic and acoustic waves. The elastic equivalents of such objects are made of sub-wavelength resonating beams fixed to a two-dimensional plate, as presented here. Independent of a random or regular arrangement of the resonators, the metamaterial shows large bandgaps that are independent of the incident wave direction. Numerical simulations demonstrate that the insertion of a defect in the layout, as a shorter resonator, creates strong amplification of the wave-field on the defect. This energy trapping, which is localized on a spatial scale that is much smaller than the wavelength in the two-dimensional plate, leads to a >1 factor in terms of the local density of energy.
authors.affiliation: ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France andree.colombi@gmail.com, philippe.roux@ujf-grenoble.fr, matthieu.rupin@ujf-grenoble.fr.
authors.forename: Andrea
authors.initials: A
authors.lastname: Colombi
authors.affiliation: ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France andree.colombi@gmail.com, philippe.roux@ujf-grenoble.fr, matthieu.rupin@ujf-grenoble.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Roux
authors.affiliation: ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France andree.colombi@gmail.com, philippe.roux@ujf-grenoble.fr, matthieu.rupin@ujf-grenoble.fr.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Rupin