Abstract: For the purpose of investigating the response characteristics of a gear pair in the accessory gear box of an aero-engine during the meshing process and the effects of the root crack propagation on gear system， using the method of the finite element simulation analysis, the dynamic meshing process and factors influencing the root crack propagation are studied based on explicit dynamics and linear elastic fracture mechanics. The crack on gear root can cause additional noise and vibration which can induce large fluctuations in rotating speed, meshing force, meshing frequency and contact stress. The root crack propagation can cause the rim fracture or tooth fracture for gear system. The occurrence of rim fracture increases as the backup ratio (i.e., rim thickness divided by tooth height) decreases and also increases as the initial crack location moves down the root of the tooth. The orientation of initial crack has little influence on crack propagation trajectory. Research results can provide reference for fault monitoring and structural design of gear structures in engineering.

Key words: Dynamic meshing;Crack propagation;Gear pair;Finite element method

摘要： 为了研究航空发动机中附件齿轮箱中的一对齿轮副在动态啮合过程中的响应特性和齿根裂纹的扩展对齿轮系统的影响，利用有限元仿真分析法，基于显示动力学和线弹性断裂力学研究了该齿轮副动态啮合过程和齿根裂纹扩展轨迹影响因素。含有齿根裂纹的齿轮在啮合过程会产生额外的振动和噪声，会引起转速、啮合力、啮合频率、接触应力产生较大波动；齿根裂纹的扩展轨迹不同会导致齿轮系统两种典型的失效模式：轮缘断裂失效或齿断裂失效，发生轮缘断裂的可能性受到轮缘厚度与齿高比值和裂纹初始位置的影响，会随着该比值的减少和初始裂纹位置沿着齿根方向下移而增大，初始裂纹方向对裂纹扩展轨迹影响很小可以忽略。研究成果在工程中可以为齿轮结构的故障监测和结构设计提供参考。

关键词: 动态啮合;裂纹扩展轨迹;齿轮副;有限单元法