As a result of manufacturing processes, real surfaces have roughness and surface curvature. The real contact occurs only over microscopic contacts, which are typically only a few percent of the apparent contact area. Because of the surface curvature of contacting bodies, the macrocontact area is formed, the area where microcontacts are distributed randomly. The heat flow must pass through the macrocontact and then microcontacts to transfer from one body to another. This phenomenon leads to a relatively high temperature drop across the interface. Thermal contact resistance (TCR) is a complex interdisciplinary problem, which includes geometrical, mechanical, and thermal analyses. Each part includes a micro and a macro scale sub-problem. Analytical, experimental, and numerical models have been developed to predict TCR since the 1930's. Through comparison with more than 400 experimental data points, it is shown that the existing models are applicable only to the limiting cases and none of them covers the general non-conforming rough contact. The objective of this study is to develop a compact analytical model for predicting TCR for the entire range of non-conforming contacts, i.e., from conforming rough to smooth sphere-flat in a vacuum.; The contact mechanics of the joint must be known prior to solving the thermal problem. A new mechanical model is developed for spherical rough contacts. The deformation modes of the surface asperities and the bulk material of contacting bodies are assumed to be plastic and elastic, respectively. A closed set of governing relationships is derived. An algorithm and a computer code are developed to solve the relationships numerically. Applying Buckingham Pi theorem, the independent non-dimensional parameters that describe the contact problem are specified. A general pressure distribution is proposed that covers the entire spherical rough contacts, including the Hertzian smooth contact. Simple correlations are offered for the general pressure distribution and the radius of the macrocontact area, as functions of the non-dimensional parameters. These correlations are compared with experimental data collected by others and good agreement is observed. Also a criterion is offered to identify the flat surface, where the effect of surface curvature on the contact pressure is negligible.; Thermal contact resistance is considered as the superposition of macro and micro thermal components. The flux tube geometry is chosen as the basic element in the thermal analysis of microcontacts. Simple expressions for determining TCR of non-conforming rough joints are derived which cover the entire range of TCR by using the general pressure distribution and the flux tube solution. (Abstract shortened by UMI.)
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