Browsing by Author "Dijksman, JA"

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    MC-DEM: a novel simulation scheme for modeling dense granular media
    Behringer, Robert P; Brodu, N; Dijksman, JA
    This article presents a new force model for performing quantitative simulations of dense granular materials. Interactions between multiple contacts (MC) on the same grain are explicitly taken into account. Our readily applicable method retains all the advantages of discrete element method (DEM) simulations and does not require the use of costly finite element methods. The new model closely reproduces our recent experimental measurements, including contact force distributions in full 3D, at all compression levels up to the experimental maximum limit of 13\%. Comparisons with traditional non-deformable spheres approach are provided, as well as with alternative models for interactions between multiple contacts. The success of our model compared to these alternatives demonstrates that interactions between multiple contacts on each grain must be included for dense granular packings.
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    Multiple-contact discrete-element model for simulating dense granular media
    (PHYSICAL REVIEW E, 2015-03-02) Brodu, N; Dijksman, JA; Behringer, Robert P
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    Spanning the scales of granular materials through microscopic force imaging.
    (Nat Commun, 2015-03-05) Brodu, N; Dijksman, JA; Behringer, RP
    If you walk on sand, it supports your weight. How do the disordered forces between particles in sand organize, to keep you from sinking? This simple question is surprisingly difficult to answer experimentally: measuring forces in three dimensions, between deeply buried grains, is challenging. Here we describe experiments in which we have succeeded in measuring forces inside a granular packing subject to controlled deformations. We connect the measured micro-scale forces to the macro-scale packing force response with an averaging, mean field calculation. This calculation explains how the combination of packing structure and contact deformations produce the observed nontrivial mechanical response of the packing, revealing a surprising microscopic particle deformation enhancement mechanism.