Characterization and application of engineered regular rough surfaces in thermal contact resistance

Proper characterization of rough surfaces is indispensable for accurate estimation of thermal contact resistance (TCR). This work is to establish a proper algorithm of characterizing surface topographies mechanically processed by lathe turning and end-face milling, which is to provide accurate and convenient methods of modeling surfaces for predicting the TCR. The correlations of surface roughness with wavelength and element height in these two types of mechanically machined surfaces are established. Based on the Fourier transforms, the models of the surface topographies of both lathe turning surfaces and end-face milling surfaces are proposed. The presented surface models are applied to both the macroscopic and the multiscale approaches of simulating the TCR to verify the accuracy of the presented surface models. A higher accuracy is verified by the comparisons between the experimental data of the TCR and the numerical results obtained from the presented surface models. The contact conditions of using lathe turning surfaces and end-face milling surfaces are simulated. The results indicate that short wavelength is able to increase real contact area, which is benefit for reducing the TCR at interface. Meanwhile, large flatness angle of lathe turning surfaces will severely decrease the real contact area and lead to increase in the TCR.