Pressure dependence of the electrical transport in granular materials

Mathieu Creyssels (1) , C. Laroche (2) , Eric Falcon (2) , Bernard Castaing (3)

1 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique
2 MSC - Matière et Systèmes Complexes
3 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

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 ($R \sim P^{-\alpha}$), with an exponent $\alpha$ 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 mediumand the percolation theories.

Mots clés: Electrical conductivity; Experiments; Statistical model; Micro-contacts; Granular media

Domaines: Autre [cond-mat.other]; Matière Molle [cond-mat.soft]; Mécanique statistique [cond-mat.stat-mech]

Mathieu Creyssels, C. Laroche, Eric Falcon, Bernard Castaing. Pressure dependence of the electrical transport in granular materials. European Physical Journal E: Soft matter and biological physics, 2017, 40 (5), pp.56. ⟨10.1140/epje/i2017-11543-3⟩. ⟨hal-01724830⟩