Electrical conduction of granular media: Experimental and numerical studies

This study presents the evolutionary behavior of electrical conduction for granular mixtures dominated by the volumetric fraction of each constituent, relative sizes, and stress condition. The chrome balls and glass beads are mixed with varying volumetric fraction and relative size ratio. The two-electrode method is used to obtain electrical conductance at different loading stages for each mixture. Three relative sizes of glass beads with respect to chrome balls are tested. As the size ratio determines the spatial configuration and corresponding connectivity of conductive granules in mixtures, the electrical conductance shows the unique evolution with varying volumetric fraction. The discrete element method is also implemented to capture the inter-particle connectivity of conductive granules. Experimental results and numerical simulation conclude that not only the fraction of conductive particles but also long range of interconnectivity of particles construct the electrical percolation path that enables carrying the electric current. This study highlights that energy transfer in granular packing can be optimized by controlling suggested dominant factors.