基于整机的中介轴承外圈剥落故障振动分析

针对某典型双转子航空发动机中介轴承外圈疲劳剥落故障诊断问题,基于整机振动耦合动力学模型,导入中介轴承外圈早期剥落故障模型,通过数值积分方法获取故障激励下的整机振动响应。提取并分析了中介轴承外圈剥落故障特征,从信号分析中发现:①出现了4倍外圈故障特征频率及其两侧以外圈旋转频率为间隔的调制边频带;②随着不平衡量增加,特征频率分量基本不变,边频带变得更加突出;③随着轴承游隙的增加,外圈故障引起的冲击更为强烈,特征频率及其调制边频均显著增加。通过比较从轴承座到机匣各测点信号的故障特征,结果表明中介轴承早期疲劳剥落产生的冲击通过轴承座传递到机匣将产生很大程度的衰减,在机匣测点信号中轴承故障特征基本消失。

Vibration analysis of peeling fault of intermediate bearing outer ring based on whole aero-engine

In view of the problem of outer ring fatigue peeling fault diagnosis of intermediate bearing in a typical double-rotor aero-engine, based on the vibration coupling dynamic model of aero-engine, the early peeling fault model of outer ring of intermediate bearing was introduced, and the vibration response of aero-engine was obtained by numerical integration. The fault features of intermediate bearing with peeling off on outer ring were extracted and analyzed. It was found from the signal analysis that: (1) there were 4 times of the characteristic frequency of outer ring fault and the modulation sidebands with the outer ring rotation frequency taken as the interval on both sides. (2) With the increase of unbalance, the characteristic frequency component was basically unchanged, and the sidebands became more prominent. (3) With the increase of bearing clearance, the impact caused by outer ring fault was more intense, and the characteristic frequency and modulation sideband frequency were significantly increased. By comparing the fault characteristics of the signals from the bearing housing to the casing, the results showed that the impact caused by the early fatigue peeling of the intermediate bearing transmitted to the casing from the bearing housing could produce a great degree of attenuation, and the bearing fault characteristics basically disappeared in the casing measurement point signals.