title: A comparison between bridges and force-chains in photoelastic disk packing.
abstract: In a dense granular material, force-chains form naturally as a backbone to support an external load. Due to the limitation of experimental techniques, the determination of the force-chain network in 3D packing is rather difficult, requiring a precise measurement of contact forces between particles. For 3D packing under gravity, it has long been proposed that bridges form as load-bearing structures. Identification of a bridge is relatively easy, requiring only the geometric information of particles. Although both concepts have existed for years, their relationship remains elusive. In this study, we aim towards resolving such a connection by comparing bridges and force-chains in packing of photoelastic disks. No direct correspondence between bridges and force-chains is observed. In addition, when a bridge grows longer, its probability of being a force-chain or part of the force-chain network decreases exponentially. Nonetheless, both are consistent in distinguishing certain properties of packing of strong hysteresis. To test the load-bearing assumption of bridges, stresses of particles in/out of bridges are analysed and compared and only minor differences are found.
authors.affiliation: Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.forename: Shuxiao
authors.initials: S
authors.lastname: Cai
authors.forename: Zunpeng
authors.initials: Z
authors.lastname: Hu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang