A numerical formulation for electric-mechanical contacts based on microscopic interface laws

This work is devoted to the development of a new constitutive model for electric–mechanical contacts, based on a micro-macro approach to describe the contact behaviour. In order to model properly the physical aspect of the problem the surface microrugosity must be considered. In the proposed contact element a macroscopic formulation, based on microscopic evidences, is set up and implemented in the contact formulation. Some thermo-mechanical macroscopic models, based on microscopic characterizations, have already been developed to compute the normal and tangential contact stiffness and the thermal contact resistance. On the basis of such macroscopic models, a similar model, suitable for the electric-mechanical field, is developed. With reference to the thermal constriction resistance the electric contact resistance is studied, assuming a flux tube around each contacting asperity, and choosing a suitable geometry for its narrowing at the contact zone. Finally these selected microscopic laws are adapted to the macroscopic numerical necessities to obtain a constitutive law for the electric-mechanical contact element. Consistent linearization is developed in order to improve the computational speed, within the framework of the implicit methods.