Junwen Zhao

Study on the Correlation Between Dynamical Behavior and Friction/Wear Mechanism Under the Effect of Grooves

In this work, the interfacial friction and wear and vibration characteristics are studied by sliding a chromium bearing steel ball (AISI 52100) over both multi-grooved and single-grooved forged steel disks (20CrMnMo) at low and high rotating speeds in order to reveal the effect mechanism of groove-textured surface on tribological behaviors. The results show that the grooves modify the contact state of the ball and the disk at the contact interface. This consequently causes variations in the normal displacement, normal force, and friction force signals. The changes in these three signals become more pronounced with increasing groove width at a low speed. The collision behavior between the ball and the groove increase the amplitude of vibration acceleration at a high speed. The test results suggest that grooves with appropriate widths could trap wear debris on the ball surface while avoiding a strong collision between the disk and the ball, resulting in an improvement in the wear states.

Experimental and Numerical Study of Friction-Induced Noise of Brake Pad Materials Having Grooved Surface

An experimental and numerical study was performed in this work to predict the squeal instability when pad specimens having different surfaces rotating on a brake disc specimen. The numerical results were consequently compared with the experimental results to investigate the effect of surface modification of pad materials on squeal generation. It was shown that surface modification of pad materials had a significant influence on the squeal instability. Diagonal grooved surface was found to be able to efficiently reduce squeal generation, which can be mainly attributed to its relatively smaller contact pressure distribution area compared to that of the smooth surface.