对某发动机尾减系统尾减输入齿轮疲劳失效的原因进行了系统的分析。通过宏观检查、断口分析、金相检验以及受力分析等, 确认了该齿轮的失效过程为: 在大弯曲载荷作用下疲劳裂纹于锥齿中部齿根部位起始, 裂纹初期沿径向呈15°左右的小角度疲劳扩展; 齿部出现裂纹后, 齿轮振动频率发生变化, 进而导致齿轮出现节径型振动, 使得裂纹逐渐沿径向疲劳扩展; 出现径向裂纹后剩余齿由于截面减少以及起始部位已基本无渗碳层其强度较低等原因, 导致剩余齿出现弯曲疲劳断裂。

A system analysis had been conducted on the end reduction input gearwheel of an engine to find its fatigue failure causes, and the failure process of the gearwheel was confirmed by means of macro inspection, fracture analysis, metallographic examination, stress analysis, etc. Fatigue crack initiated at the root of the central part of the bevel gearwheel under big bending loads. In the beginning, crack extended along the radial direction in fatigue way with a small angle about 15°. The appearance of crack caused the variation of gearwheel vibration frequency, so pitch diameter type vibration appeared in the gearwheel. At last the gearwheel crack extended along the radial direction in fatigue way. After the gearwheel crack of radial direction, reduction of the cross-section and low intensity because of there being almost no infiltration layer in the starting site caused remaining part of the gearwheel to appear a secondary bending fatigue fracture.