Effect of contact statistics on electrical contact resistance

A model for the electrical contact of rough surfaces, extending Greenwood's equation for conduction through a cluster of circular contacts to a system in which the probability of a contact spot at a given location was defined in statistical term, was presented. An idealized fractal rough surface was defined using the random midpoint displacement algorithm. The size distribution of contact spot was assumed to be given by the intersection of the surface with a constant height plane. It was found that inclusion of the finer scale detail in the fractal surface, equivalent to reducing the sampling length in the measurement of the surface, caused the predicted resistance to approach the perfect contact limit.