A new mechanical–electrical approach to the wheel-rail contact

The need to understand the short-circuit phenomenon between two rails brought into contact by a train has led to a new mechanical–electrical approach to the wheel-rail contact based on tribological analysis. Contact between the wheel and rail generates a layer called the “third-body”, composed of particles detached from the two bodies in contact. It can be sheared through its thickness and become the location of substantial velocity gradients. The electrical resistance of this third body is investigated in order to identify possible electrical problems. Consequently, an Atomic Force Microscope (AFM) is used to distinguish the zones of different electrical conductivity. Due to the difficulty of measuring local characteristics inside the contact, the electrical effects are incorporated in numerical simulations using a Discrete Element Method (DEM). Directions for understanding the short-circuit mechanism in the wheel-rail contact are given, underlining the multi-scale and multi-physical aspects of the problem.