Thermal contact conductance between balls and bearing rings

Abstract

The thermal contact conductance (TCC) between balls and bearing rings is predicted by proposing the TCC model between the curved and spherical surfaces. The Weierstrass-Mandelbrot function is applied to characterize the microscopic topography of surfaces. The fractal contact model is constructed by considering the elastic, elastic-plastic, and plastic deformations of microprotrusions, and then an effective contact coefficient is built to modify the fractal contact parameters. Finally, the TCC modeling method is proposed by considering the elastic and plastic TCCs of different contacting microprotrusions with different sizes. The experiments of TCCs were conducted under different conditions to verify the validity of the proposed model. The results show that the predicted TCCs fit well with measured values and that the predictive accuracy can be improved greatly by considering the effective contact coefficient. Then the effect of critical factors on TCCs is discussed, and the TCC increases with the external load, and increases with the fractal dimension D and decreases with the scaling constant G. The TCC of the dynamic lubricated ball bearing is much greater than that of the static lubricated ball bearing and the TCC of the static lubricated ball bearing is much greater than that of the static non-lubricated ball bearing.