title: Nonlinear waves in disordered diatomic granular chains.
abstract: We investigate the propagation and scattering of highly nonlinear waves in disordered granular chains composed of diatomic (two-mass) units of spheres that interact via Hertzian contact. Using ideas from statistical mechanics, we consider each diatomic unit to be a "spin," so that a granular chain can be viewed as a spin chain composed of units that are each oriented in one of two possible ways. Experiments and numerical simulations both reveal the existence of two different mechanisms of wave propagation: in low-disorder chains, we observe the propagation of a solitary pulse with exponentially decaying amplitude. Beyond a critical level of disorder, the wave amplitude instead decays as a power law, and the wave transmission becomes insensitive to the level of disorder. We characterize the spatiotemporal structure of the wave in both propagation regimes and propose a simple theoretical interpretation for a transition between the two regimes. Our investigation suggests that an elastic spin chain can be used as a model system to investigate the role of heterogeneities in the propagation of highly nonlinear waves.
authors.affiliation: California Institute of Technology, Pasadena, 91125, USA.
authors.forename: Laurent
authors.initials: L
authors.lastname: Ponson
authors.forename: Nicholas
authors.initials: N
authors.lastname: Boechler
authors.forename: Yi Ming
authors.initials: YM
authors.lastname: Lai
authors.forename: Mason A
authors.initials: MA
authors.lastname: Porter
authors.forename: P G
authors.initials: PG
authors.lastname: Kevrekidis
authors.forename: Chiara
authors.initials: C
authors.lastname: Daraio