title: Does gravity cause load-bearing bridges in colloidal and granular systems?
abstract: We study structures which can bear loads, "bridges", in particulate packings. To investigate the relationship between bridges and gravity, we experimentally determine bridge statistics in colloidal packings. We vary the effective magnitude and direction of gravity, volume fraction, and interactions, and find that the bridge size distributions depend only on the mean number of neighbors. We identify a universal distribution, in agreement with simulation results for granulars, suggesting that applied loads merely exploit preexisting bridges, which are inherent in dense packings.
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, Kings Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: M C
authors.initials: MC
authors.lastname: Jenkins
authors.forename: M D
authors.initials: MD
authors.lastname: Haw
authors.forename: G C
authors.initials: GC
authors.lastname: Barker
authors.forename: W C K
authors.initials: WC
authors.lastname: Poon
authors.forename: S U
authors.initials: SU
authors.lastname: Egelhaaf