Numerical investigation on the electrical transmission ability of a shearing powder layer

Recent developments in powder technology gave birth to a new lubricant—powder lubricant. Compared to liquid lubricant, powder lubricant like graphite powder has several advantages, such as good electrical conductivity and good thermal resistance. Such advantages are especially appreciated in sliding electrical contacts. Thus, the study of the electrical transmission ability of a shearing powder layer under different dynamical constraints appears to have a great interest. Recent works allowed to model the coupling of mechanical and electrical effects in a discrete medium. This algorithm was extended to study the electrical properties of a shearing powder layer with discrete element method. The mechanical and electrical behaviors of the sample were studied in different dynamical regimes, characterized by the inertial number I. The results exhibit an interesting relationship between the average contact resistance and the inertial number I. An exponential increase of the sample’s electrical resistance as well as the induced electrical noise are observed closed to the dense flow limit. Such observations underline the fact that to ensure the electrical transmission ability of the powder layer, one must keep the particle size and shear rate small, and a sufficiently large pressure.