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

摘要： 针对某型号驻车制动器在产品开发与验证过程中出现的疲劳寿命不达标，以及销子、 拉线、支撑板等零件断裂的问题，文章开展了失效分析与优化改进研究。通过断口分析、金 相观察、硬度检测与应力计算等方法，确定销子为导致制动器早期失效的关键件。分析表明， 销子因强度不足，在试验中发生磨损与松旷，进而引发疲劳断裂；销子松旷进一步造成支撑 板受力增大，拉线受力方向改变，锁头部位弯曲应力显著增加并导致断裂，最终致使制动器 整体寿命低于设计目标。基于上述失效机理，对销子材料及强度进行了优化，并改进了拉线 锁头部位的结构设计，有效提高了制动器工作稳定性，降低了应力集中。经针对性改进后， 制动器寿命得到显著提升，对同类零部件在研发阶段的失效预防、性能提升及试验标准完善 具有重要的工程借鉴与理论参考价值。

关键词: 驻车制动器；疲劳断裂；应力集中