Interface Contact Coefficients Used in Thermal Engineering Analyses

The conductive heat transfer across two contacting surfaces is difficult to predict because the surfaces will always have imperfections such as roughness, voids and non-flatness. These imperfections occur on flat plates, honeycomb panels or any mating surfaces that transfers heat across their interfaces. These imperfections are hard to characterize experimentally and will reduce the conductive heat transfer between the surfaces and thereby degrade the thermal performance. Quantitative understanding of the phenomenon of surface contact improves the ability to accurately predict temperatures across thermal boundaries. This is important for optimizing the thermal performance of components such as radiators and electronic subassemblies of spacecraft and instruments where size and weight are a premium. The purpose of this paper is to show what parameters, such as contact pressure, surface roughness, flatness, and bolt spacing, are involved in predicting the conductive contact coefficient. The purpose of the data presented in this paper is to show how these parameters affect the magnitude and performance trends of the contact coefficient. and is not presented to be used for design or analysis purposes.