Pressure dependence of the electrical transport in granular materials

M. Creyssels^{1, 2}, C. Laroche², E. Falcon³and B. Castaing³

¹Laboratoire de Mécanique des Fluides et Acoustique, Ecole centrale de Lyon, CNRS, Univ. de Lyon, 69134 Ecully, France
² Univ Paris Diderot, Sorbonne Cité, MSC, CNRS, UMR 7057, 75013 Paris, France
³ Laboratoire des Ecoulements G´eophysiques et Industriels, Univ. Grenoble Alpes, CNRS, 38058 Grenoble, France

Reference: European Physical Journal E 40, 56 (2017)

URL: http://link.springer.com/article/10.1140%2Fepje%2Fi2017-11543-3

DOI: https://doi.org/10.1140/epje/i2017-11543-3

Key words: Flowing Matter, Granular Matter

Abstract: We report on systematic measurements of the electrical resistance of one- and three-dimensional (1D and 3D) metallic and oxidized granular materials under uni-axial compression. Whatever the dimension of the packing, the resistance follows a power law versus the pressure (R ~ P^a), with an exponent a much larger than the ones expected either with elastic or plastic contact between the grains. A simple model based on a statistical description of the micro-contacts between two grains is proposed. It shows that the strong dependence of the resistance on the pressure applied to the granular media is a consequence of large variabilities and heterogeneities present at the contact surface between two grains. Then, the effect of the three-dimensional structure of the packing is investigated using a renormalization process. This allows to reconcile two extreme approaches of a 3D lattice of widely distributed resistances: the effective medium and the percolation theories.

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Press item:
EPJ E Highlight, 8 June 2017 - Granular material conductivity increases in mysterious ways under pressure

Image of
grains of copper powder through a microscope

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