Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

A hybrid DEM model suitable for micro and nano particulate systems incorporating long-range force contributions

F. Sarangia, S.J. Antonya,*, M.R. Kuhnb
aInstitute of Particle Science and Engineering, Department of Chemical Engineering, University of Leeds LS2 9JT, England, UK bDepartment of Civil Engineering, School of Engineering, University of Portland, Portland, OR 97203, USA

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ABSTRACT
Discrete element method (DEM) is a powerful tool for modelling the macroscopic and internal mechanics of particulate assemblies under mechanical loading. However, existing versions of DEM codes normally account for the inter-particle forces only when contiguous particles touch or overlap. In this paper, we examine the effects of long-range inter-particle forces acting between individual particles using DEM. Simulations were performed incorporating the contribution of repulsive force acting between particles even when the particles do not touch each other. When the particles touch/overlap with neighbouring particles, then inter-particle interactions are governed by a conventional linear spring-dashpot model; added to this is the contribution of normal force corresponding to zero separation distance between the particles. The simulations were of two types: (a), where no long-range forces were acting between particles (Type-0), and (b), where long-range forces were acting between particles (Type-1), which were entirely repulsive in nature. The long-range contact force data originates from hypothetical force curves similar to those obtained from Atomic Force Microscopy (AFM) experiments for powders with repulsive inter-particle interactions. Type-1 simulations are performed for three cases (AC) of data describing force-separation curves that have identical approach and retraction loci. This preliminary study shows that the long-range force contribution significantly affects the macroscopic and internal behaviour of particulate assemblies under mechanical loading.

Keywords:  Powder mechanics; Force-separation relations; Repulsive forces; Particulate materials; DEM

* Corresponding author. Tel.: +44 1133 432 409; Fax: +44 1133 432 405; E-mail: S.J. Antony@leeds.ac.uk