title: Shear stress fluctuations in the granular liquid and solid phases.
abstract: We report on experimentally observed shear stress fluctuations in both granular solid and fluid states, showing that they are non-Gaussian at low shear rates, reflecting the predominance of correlated structures (force chains) in the solidlike phase, which also exhibit finite rigidity to shear. Peaks in the rigidity and the stress distribution's skewness indicate that a change to the force-bearing mechanism occurs at the transition to fluid behavior, which, it is shown, can be predicted from the behavior of the stress at lower shear rates. In the fluid state stress is Gaussian distributed, suggesting that the central limit theorem holds. The fiber bundle model with random load sharing effectively reproduces the stress distribution at the yield point and also exhibits the exponential stress distribution anticipated from extant work on stress propagation in granular materials.
authors.affiliation: Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, sede di Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Roma, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Dalton
authors.forename: F
authors.initials: F
authors.lastname: Farrelly
authors.forename: A
authors.initials: A
authors.lastname: Petri
authors.forename: L
authors.initials: L
authors.lastname: Pietronero
authors.forename: L
authors.initials: L
authors.lastname: Pitolli
authors.forename: G
authors.initials: G
authors.lastname: Pontuale