齿轮箱作为高速动车组牵引系统重要传动设备，在运用过程中主要承受来自于线路激扰的冲击作用，齿轮箱体出现了疲劳裂纹。以某型齿轮箱体为研究对象，统计开裂齿轮箱体的运营里程并对其进行疲劳断口分析，疲劳裂纹源发生于齿轮箱体内侧拐角处，该部位存在因齿轮箱体结构及凹坑等缺陷引起的应力集中。基于高速铁路线路测试，得到典型工况下轴箱、齿轮箱体的振动加速度信号及表面的动应力响应，并对齿轮箱体的自由模态进行分析研究。研究结果表明，列车高速直线运行时，轮轨激扰引起的齿轮箱体振动频率与其固有频率产生了交集，齿轮箱体产生局部共振，共振使齿轮箱体局部产生较高的动应力幅值，从而导致箱体出现裂纹。该研究对确保高速列车运用安全及齿轮箱体新型结构的设计提供参考。

Gearbox is an important transmission equipment of high-speed electric multiple unit(EMU) traction system and suffer the impact mainly from the line turbulence,which induces the fatigue cracks in service. Aiming at a gearbox in this paper,the life mileage statistics of the gearbox and the crack macro analysis of the gearbox fracture section are demonstrated,the origination of fatigue crack occurs at the inside corner of the gearbox,which exists stress concentration due to the structure and some structural defects,such as pit. On the basis of the online test,the vibration acceleration signal of axle box and gearbox and the dynamic stress response of gearbox surface were received,simultaneously the modal of the gearbox was analyzed. The results show that the exciting frequency from the line turbulence is mixed with the gearbox natural frequency and the resonance of the gearbox housing happens,which induces the high dynamic stress amplitude and the gearbox housing appears the fatigue crack. This idea is helpful to ensure the high speed train running in safety and a reference to the design of the new gearbox housing is provided.