About the influence of friction and polydispersity on the jamming behavior of bead assemblies
Mathematics Institute, École Polytechnique Fédérale de Lausanne - EPFL, CH-1015, Lausanne, Switzerland
2 armasuisse, Feuerwerkerstrasse 39, CH-3602, Thun, Switzerland
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Published online: 14 June 2007
We study the jamming of bead assemblies placed in a cylindrical container whose bottom is pierced with a circular hole. Their jamming behavior is quantified here by the median jamming diameter, that is the diameter of the hole for which the jamming probability is 0.5. Median jamming diameters of monodisperse assemblies are obtained numerically using the Distinct Element Method and experimentally with steel beads. We obtain good agreement between numerical and experimental results. The influence of friction is then investigated. In particular, the formation of concentric bead rings is observed for low frictions. We identify this phenomenon as a boundary effect and study its influence on jamming. Relying on measures obtained from simulation runs, the median jamming diameter of bidisperse bead assemblies is finally found to depend only on the volume-average diameter of their constituting beads. We formulate this as a tentative law and validate it using bidisperse assemblies of steel beads.
PACS: 45.70.-n Granular systems – / 83.10.Rs Computer simulation of molecular and particle dynamics – / 45.70.Cc Static sandpiles; granular compaction –
© EDP Sciences/Società Italiana di Fisica/Springer-Verlag, 2007