Three triangular friction block configurations are commonly employed in high-speed train brake systems, namely, unperforated, perforated configuration with one circular hole, and perforated with three circular holes. In this study, we adopted these friction block types to investigate the effect of perforated friction block configurations on the brake performance of high-speed trains based on a self-developed brake test rig. The results indicate the significant impact of the number of the holes on the wear behavior, temperature distribution, and vibration characteristics of the brake interface. The friction surface of the unperforated block is covered by wear debris, while the perforated blocks produce less wear debris. Furthermore, the one-hole block exhibits a more uniform temperature distribution and better vibration behavior than that with three holes. The friction brake is a dynamic process, during which separation and attachment between the pad and disc alternatively occur, and the perforated structure on the friction block can both trap and expel the wear debris.

In this paper, a PZT (lead zirconate titanate)-based absorber and energy harvester (PAEH) is used for passive control of friction-induced stick-slip vibration in a friction system. Its stability condition coupled with PAEH is analytically derived, whose efficiency is then demonstrated by numerical simulation. The results show that the structural parameters of the PAEH can significantly affect the system stability, which increases with the mass ratio between the PAEH and the primary system, but first increases and then decreases with the natural frequency ratio between the PAEH and the primary system. The impacts of the electric parameters of the PAEH on the system stability are found to be insignificant. In addition, the PAEH can effectively suppress the stick-slip limit cycle magnitude in a wide working parameter range; however, it does not function well for friction systems in all the working conditions. The stick-slip vibration amplitude can be increased in the case of a large loading (normal) force. Finally, an experiment on a tribo-dynamometer validates the findings of the theoretical study, in which the vibration reduction and energy harvesting performance of the PAEH is fully demonstrated.

In this study, piezoelectric elements were added to a reciprocating friction test bench to harvest friction-induced vibration energy. Parameters such as vibration acceleration, noise, and voltage signals of the system were measured and analyzed. The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction-induced vibration noise (FIVN). Additionally, the wear of the friction interface was examined via optical microscopy (OM), scanning electron microscopy (SEM), and white-light interferometry (WLI). The results show that the surface wear state improved because of the reduction of FIVN. In order to analyze the experimental results in detail and explain them reasonably, the experimental phenomena were simulated numerically. Moreover, a simplified two-degree-of-freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects, dynamics, and tribological behaviors of the added piezoelectric elements to the original system.