Thermal contact conductance modeling of baring outer ring/bearing housing interface

Abstract

Currently, no model could be used to readily predict the TCR of baring outer ring/bearing housing interface, then a thermal contact conductance (TCC) model between cylindrical surfaces with transition fits is constructed. The topography is described by the fractal geometry to characterize the multiscale and self-affinity behaviors and two stochastic variables are introduced into the fractal function to guarantee the random and disordered features. Then the contact states of contact points are analyzed, and a new fractal inner contact model is established. An effective contact factor is introduced to modify the contact parameters. Eventually, the predictive model of TCCs is constructed by summing up the TCCs of all the contacting protrusions with different scales. To demonstrate the validity of the TCC model, the measuring setup of TCCs was developed, and then the tests were conducted. The results show that the average deviations between the measured data and predicted TCCs are 10.25% and 8.73% for SS304 and carbon steel, respectively. When the effective contact factor is not considered, the average deviations between the predicted TCCs and measured data are 25.47% and 20.61% for SS304 and carbon steel, respectively. Then the necessity to introduce the effective contact factor is verified. For SS304, the prediction accuracy of the present model is 15.22%, 56.36%, and 31.55% higher than that of the present model without effective contact factor, M-T model, and Zou model, respectively. For carbon steel, the prediction accuracy of the present model is 11.88%, 63.76%, and 34.87% higher than that of the present model without effective contact factor, M-T model, and Zou model, respectively. Finally, the effects of the surface roughness, the protrusion top radius, the effective contact factor, and the transition fit on TCC are discussed. The results show that TCC decreases with surface roughness. The TCC with different protrusion top radii is greater than that with identical top radius. The TCC increases with the effective contact factor slowly and then the growth rate increases rapidly. Besides, the TCC increases with transition fit sharply at the early stage, and then increases slowly for both SS304 and carbon steel.