A Multiscale Model of Thermal Contact Resistance Between Rough Surfaces

Abstract

A new multiscale model of thermal contact resistance (TCR) between real rough surfaces is presented, which builds on Archard’s multiscale description of surface roughness. The objective of this work is to construct the new model and use it to evaluate the effects of scale dependent surface features and properties on TCR. The model includes many details affecting TCR and is also fairly easy to implement. Multiscale fractal based models often oversimplify the contact mechanics by assuming that the surfaces are self-affine, the contact area is simply a geometrical truncation of the surfaces, and the pressure is a constant value independent of geometry and material properties. Concern has grown over the effectiveness of frequently used statistical rough surface contact models due to the inadequacies in capturing the true multiscale nature of surfaces (i.e., surfaces have multiple scales of surface features). The model developed in this paper incorporates several variables, including scale dependent yield strength and scale dependent spreading resistance to develop a new model that can be used to evaluate TCR. The results suggest that scale dependent mechanical properties are more influential than scale dependent thermal properties. When compared to an existing TCR model, this very inclusive model shows the same qualitative trend. Results also show the significance of capturing multiscale roughness when addressing the thermal contact resistance problem.