Evaluation of Thermal Contact Resistance at the Interface Composed of Dissimilar Materials

When jointed portions of structures and machines are subjected to thermal loads, various problems and troubles occur due to the difference in thermal expansions between mating parts. In order to accurately analyze thermal and mechanical behaviors of the joints, the effect of thermal contact resistance must be taken into account. In this paper, thermal contact coefficient, which is the reciprocal of thermal contact resistance, at the interface composed of dissimilar materials is quantitatively measured by infrared thermography. The target materials are common engineering materials such as carbon steel, stainless steel and aluminum alloy. It has been shown in the previous papers that there exits a significant directional effect in thermal contact coefficients when the mating surface is composed of different materials. That is, thermal contact coefficient has a larger value when the heat flows from the material with lower thermal conductivity to the one with higher thermal conductivity. The effects of contact pressure and surface roughness on the coefficient are also evaluated in this work. Using the measured data, an empirical equation to estimate thermal contact coefficient is proposed, for the purpose of engineering applications, which correlates closely with the experimental data.