A multiscale model for thermal contact conductance of rough surfaces under low applied pressure

Abstract

The scope of this work is to investigate how the interfacial pressure and the scale of the asperities as well as the temperature, influence the thermal contact conductance TCC in rough surfaces under low pressure. For that, a two- dimensional numerical model is developed, in which the macroscopic TCC coefficient is obtained from the solution of the heat conduction problem at the scale of asperities. The morphology of the rough surface, which is characterized by a fractal interpolation function, is applied to mechanical and thermal modeling. The contact model calculates the different contact scales at the asperities by considering elastic, elastic–plastic and fully plastic deformations as well as the changes in material parameters due to the temperature. Finally, several contacting asperities are combined to get the macroscopic TCC coefficient. The obtained results showed that at small values of normal pressure, TCC becomes smaller at higher resolutions of the interface where waviness is more intense. On the contrary, the rate of increase of TCC with the increase of the normal pressure is larger at these interfaces at larger values of normal pressure, where the smaller scales of asperities deform more easily. This phenomenon appears to be more intense with the time as the temperature of the interface rises and consequently more plastifications of the asperities occur.