Abstract: The vibration fatigue problem of the chassis cantilever structure of trucks is prominent, which seriously affects user satisfaction as a production tool. The article focuses on the cracking problem of a heavy-duty truck's rear mudguard during durability testing, and conducts vibration fatigue simulation analysis. Combining modal and road spectrum energy distribution, the simulation results are analyzed and judged to be consistent with the actual vehicle problem, effectively reproducing the failure mode of the fault, and further application of size optimization techniques to determine improvement plans for complex variable cross-section structures. The proposed solution ultimately passed real-vehicle testing, demonstrating the effectiveness of the analytical method and providing a reference for addressing similar issues in chassis cantilever structural components of light and heavy trucks.

Key words: fender; vibration fatigue; dimension optimization; structural durability

摘要： 商用卡车的底盘悬臂类结构振动疲劳问题突出，作为生产工具严重影响用户的满意度。 文章针对某重卡后挡泥板在耐久试验中出现的开裂问题，开展振动疲劳仿真分析，结合模态 和路谱能量分布，分析判断仿真结果与实车问题一致，有效复现故障失效模式，并且进一步 应用尺寸优化技术确定复杂变截面结构的改进方案。最终该方案通过实车试验，证明了分析 方法的有效性，为解决轻重卡底盘悬臂结构件类似问题提供参考。

关键词: 挡泥板；振动疲劳；尺寸优化；结构耐久