复杂激励下涡轴发动机中央从动锥齿轮故障机理

Failure analysis on central drive bevel gear of turbo-shaft engine with complex excitation

针对某小型涡轴发动机燃气发生器转子前端中央从动锥齿轮发生的疲劳断裂故障,同时考虑了齿面高频啮合激励作用和转子-从动锥齿轮耦合振动带来的影响,研究了从动锥齿轮的振动响应特征。结果表明:齿面啮合激励会激起从动锥齿轮5节径振型,同时,转子-从动锥齿轮耦合振动会对锥齿轮产生转子转速2倍频(2×)激励,并激起锥齿轮的俯仰模态振型,除此之外,齿面附加约束作用改变了该振型下的振动应力分布、使疲劳裂纹沿径向扩展,与故障现象相符,证明了该故障机理分析的正确性。

A fatigue failure of the central driven bevel gear was found at the front end of the high pressure rotor of a small turbo-shaft engine. Taking into consideration of both the gear teeth meshing and rotor-gear coupling vibration, the vibration response of the driven bevel gear under the combined influences of tooth surface meshing excitation and rotor lateral vibration excitation was investigated. The analysis results showed that the gear teeth meshing caused the 5 th nodal diameter shape vibration, while the coupled vibration of the rotor-driven gear system led to a 2× excitation and then excited the swing shape vibration of the driven bevel gear. Meanwhile, the additional constraints arousing from the gear teeth meshing changed the vibration stress distribution of the swing shape vibration, which then forced the fatigue crack to propagate radially through the gear. The distribution of vibration stress is consistent with the phenomenon of the driven gear fatigue failure, which proves the correctness of the failure mechanism analysis.