Discrete breathers and intrinsic energy localization in one-dimensional diatomic granular crystals

Stéphane Job , Nicholas Boechler , Georgios Theocharis , Panayotis G. Kevrekidis , Mason A. Porter , Chiara Daraio

We report the experimental observation of modulational instability and discrete breathers in a one-dimensional diatomic granular crystal composed of elastic spheres that interact via the nonlinear Hertz potential. Our crystal consists of an alignment of 19.05-mm-diameter steel and aluminium spheres compressed by a static load in the axial direction. We first characterize the linear spectrum of the crystal by analyzing the low amplitudes transmitted vibrations; we observe the existence of acoustic and optical bands separated by a band gap. We then illustrate theoretically and numerically the modulational instability of the lower edge of the optical band. We finally show experimentally that modulational instability leads to the dynamical formation of long-lived and spatially localized breather structures [Phys. Rev. Lett. 104, 244302 (2010); Phys. Rev. E 82, 056604 (2010)].

Domaines: Acoustique [physics.class-ph]

Stéphane Job, Nicholas Boechler, Georgios Theocharis, Panayotis G. Kevrekidis, Mason A. Porter, et al.. Discrete breathers and intrinsic energy localization in one-dimensional diatomic granular crystals. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811291⟩