A method to improve the tribological performance of Cu-based powder metallurgy friction materials for the high-speed trains braking system: Enhancement of the performance of the friction block disc spring

Abstract

The tribological performance of Cu-based powder metallurgy (PM) friction materials, commonly known as friction blocks, is vital for ensuring effective braking and ride comfort in high-speed trains. Thus, it is essential to identify effective methods to enhance the tribological properties of these materials. This study proposed a floating structure design for friction materials, enhancing their deformation capacity by altering the disc spring material. This innovative approach is intended to improve the tribological performance of Cu-based PM friction materials, ensuring better braking efficiency and ride comfort in high-speed trains. Drag braking simulations were conducted on a custom-built test rig to evaluate high-speed train braking performance using four different disc spring materials. The study focused on analyzing friction-induced vibration and noise (FIVN), along with interface friction and wear behavior. A wear model incorporating dynamic effects was developed, and finite element models (FEM) based on the experimental setup and conditions were created. These models enabled coupled simulations to analyze braking interface wear and friction-induced vibrations (FIV). The results indicate that the 60SM disc spring significantly reduces FIVN, promotes uniform friction block wear, ensures consistent interface contact, and minimizes FIVN levels. In contrast, the 304 disc spring increases contact stiffness at the braking interface, which leads to abnormal wear and higher FIVN levels. Furthermore, the choice of disc spring material directly influences contact stress and deformation in both friction blocks and disc springs, thereby impacting the braking system's dynamic performance and the tribological behavior of Cu-based PM friction materials. Thus, optimizing the deformation capacity of friction materials through floating structure designs emerges as a practical strategy to enhance the tribological performance of Cu-based PM materials in high-speed train braking systems.