Experimental Investigation and Numerical Simulation on the Role of Sphere Indenter in Measuring Contact Resistance of Flat Rivets

There has been increasing demand to research the measuring method to characterize the batch consistency of contact rivets. An automated test equipment has been described that makes it possible to measure the electrical contact resistance with high efficiency. The relationship between contact force and contact resistance during the loading and unloading process was measured explicitly using AgPd alloy, stainless steel and sapphire substrate material with Au coatings as sphere indenters separately. To explain the phenomena of contact resistance decreasing more slowly than the traditional theoretical results during loading, the indenter with coating and rivet are modeled by using the commercial FEM software COMSOL Multiphysics. Besides the constriction resistance, the transition region Au coating resistance and the bulk resistance of the substrate are deduced from the simulated current lines profiles and iso-potentials. The difference of electrical conductivity between indenter material and gold coating is the reason for the occurrence of the transition region.