Thermal Evolution of Hot Spots in Thermally Nonlinear Carbon Graphite Sliders

Abstract

Frictional heating of a thermal mound (or hot spot) present on the interface between a carbon graphite block sliding against a fast moving conductor is simulated. Heating of this mound due to frictional power dissipation is modeled as a collection of internal heat sources uniformly distributed within a very shallow volume (or layer) located directly beneath the sliding contact interface. The thermal mound, assumed to be motionless on and originating from the carbon graphite block, possesses the extreme temperature dependent thermal conductivity and heat capacity common to carbon graphite materials. Evolution of thermal mound temperatures from cold to hot is studied as a function of the intensity of the internal heat source distribution and the thickness of the heat source layer. For a fast moving conducting body sliding against the graphite block, it is shown that (a) an optimal heat source layer thickness exists, whereby temperatures maximize for this thickness and (b) for a sufficiently high heat source intensity, thermal instability of the mound is possible.