The role of interparticle contact in conductive properties of random particulate materials

The effective conductivity of material systems consisting of contacting particles is studied computationally using a model of monodisperse circular disks. The electrical or thermal conductivity is computed by modeling the relevant mechanical contact problem followed by a steady-state conduction analysis. The interparticle contact resistance is incorporated via the introduction of gap conductance in the contact pairs. Monte Carlo simulations show that the overall effective conductivity is much lower than that predicted by the model using an overlap assumption, even when the contact resistance is zero. The results also display a nonlinear relationship between the contact resistance and the effective conductivity. Therefore, in practical applications involving particulate inclusions of high density, the interfacial contact must be considered to reliably predict the relevant transport properties. Although the methodology is developed in the context of circular disks, it can be extended to deal with more general situations.