Abstract: This paper focuses on the cracking failure of the tread bracket for a certain vehicle model, aiming to resolve the quality claim issue caused by tread bracket fracture. First, the driving mileage and failure frequency of the failed vehicles are investigated and analyzed to determine whether the quality failure originates from design deficiencies. Second, a combined analysis method integrating real-vehicle load conditions and virtual validation is adopted to evaluate the fatigue life of the tread bracket. The random vibration fatigue analysis based on vibration test data shows that the minimum fatigue life region of the tread bracket is consistent with the actual fracture position, confirming the failure mode of the tread bracket. Third, structural optimization is carried out by strengthening the structural strength in the vibration direction, and a cross-comparison analysis of the optimization schemes is conducted to verify the improvement effect, with the fatigue life increased by approximately 10 000 times. Finally, based on the analysis results, a weight-reduction optimization is performed, achieving about 4% weight reduction to offset the mass increase caused by the structural optimization scheme. This paper provides a reliable analysis and verification approach for product design and post-market quality issue analysis of similar products, reducing structural failures caused by insufficient validation during the design phase, and offering reference significance for subsequent product development and design.

Key words: tread bracket; real-vehicle load; fatigue life; structural optimization

摘要： 文章主要以某车型踏步支架开裂失效问题为研究对象，旨在解决踏步支架断裂引起的 质量索赔问题。首先，对失效车辆的行驶里程与问题发生频次等方面进行调研分析，判断质 量失效是否源于设计原因。其次，运用实车工况载荷与虚拟验证结合的分析方法，分析踏步 支架疲劳寿命。基于振动测试数据的随机振动疲劳分析结果显示，踏步支架最低疲劳寿命区 域与实际断裂位置一致，确认踏步支架失效形式。再次，通过加强振动方向结构强度的方法 进行结构优化，并对优化方案进行横向对比分析，验证其改进效果，疲劳寿命提升约 10 000 倍。最后，根据分析结果对结构进行减重优化，减重约 4%，抵消结构优化方案带来的质量增 加。文章为此类产品在产品设计与后期质量问题分析方面提供了一种可靠的分析验证方案， 减少由于设计阶段验证不充分导致的结构失效，对后续产品开发设计有一定的借鉴意义。

关键词: 踏步支架；实车载荷；疲劳寿命；结构优化