关键词: 驻车制动器；疲劳断裂；应力集中

Abstract: In response to the issues of fatigue life failure and fracture of components such as pins, cables, and support plates during the product development and validation process of a certain type of parking brake, this study conducted failure analysis and optimization improvements. Through methods including fracture analysis, metallographic examination, hardness testing, and stress calculation, the pin is identified as the critical component causing early failure of the brake. Analysis reveal that the pin, due to insufficient strength, experienced wear and loosening during testing, leading to fatigue fracture. The loosening of the pin further increased the stress on the support plate, altered the force direction on the cable, and significantly elevated the bending stress at the cable lock head, resulting in fracture. Ultimately, these issues caused the overall lifespan of the brake to fall below the design target. Based on the failure mechanism, the material and strength of the pin are optimized, and the structural design of the cable lock head is improved, effectively enhancing the operational stability of the brake and reducing stress concentration. After targeted improvements, the lifespan of the brake is significantly increased. This study provides valuable engineering insights and theoretical reference for failure prevention, performance enhancement, and testing standard improvement of similar components during the research and development phase.

Key words: parking brake; fatigue fracture; stress concentration