Study on thermal fatigue damage mechanisms for high-speed train’s wheel-mounted brake disc considering multiaxial stress state

The wheel-mounted brake disc is a critical component of the high-speed train brake system, and the bolt hole is identified as a high-risk region for fatigue failure in practice. This study proposes a thermal fatigue damage analysis method incorporating the multiaxial stress state to explore the complex failure mechanisms for wheel-mounted brake discs. A finite element model of a typical wheel-mounted brake disc is established and validated for a closer-to-reality prognostication. The thermodynamic response of the brake disc during emergency braking is analyzed, and the fatigue life of the critical nodes is predicted based on the multiaxial stress state. The results reveal that the multiaxial stress in the bolt-hole region jointly contributes to the formation of fatigue damage, as opposed to being caused by a specific uniaxial one. Additionally, the evolution of fatigue crack propagation is further investigated by simulation analysis. The findings indicate that the propagation in axial is more likely to result in fatigue failure, compared to the radial direction. This study is supposed to provide insights into the mechanisms of thermal fatigue damage in wheel-mounted brake discs and offer guidance for the structural design of critical brake components as well as the development of effective maintenance strategies.