3. At the heart of tribological interfaces

3.1 From reality to models

When we focus on the interface separating two bodies in contact, we can see that, under certain conditions (high pressures and shear rates), it flows like a fluid. Indeed, Godet [39] and Berthier [13] have demonstrated that this more or less heterogeneous and discontinuous interface, or more commonly known in tribology as the "third body", can have variable thicknesses (ranging from a few nanometers to several tens of micrometers) and flow with a rheology that is unknown a priori. This discontinuous interface is artificially found in powder lubrication, but in this case the properties of the medium are known a priori. However, the behavior of this medium in the face of high shear pressures and velocities can change, making the interpretation of experimental...