中介轴承故障动力学建模与振动特征分析

中介轴承是航空发动机转子的关键支承部件之一,工作转速高,润滑条件差,易发生故障。基于动力学模型的故障机理研究可以为中介轴承故障诊断提供依据。以Gupta圆柱滚子轴承复杂动力学建模方法为基础,考虑外圈的运动建立了中介轴承动力学模型,通过试验对模型进行验证。在此基础上,分别考虑滚道表面形貌和轴承间隙的变化,建立中介轴承磨损故障动力学模型;针对中介轴承滚道表面剥落等局部损伤故障,考虑滚动体通过损伤区域时趋近量和接触载荷方向的改变,建立中介轴承局部损伤故障动力学模型。利用所建故障动力学模型对不同磨损状态下中介轴承外圈径向振动响应进行研究。研究表明,出现磨损后,振动响应频率中出现若干随机成分;对于局部损伤和磨损的复合故障,随着磨损加剧,振动幅值随之增大,随机成分所占比重增加,损伤的故障特征不明显。

Dynamic Modeling and Vibration Analysis for Inter-shaft Bearing Fault

Inter-shaft bearings is one of the key supporting components of aero-engine rotor. The inter-shaft bearings is prone to failure because of the high speed and poor lubrication working conditions. Dynamic model based fault mechanism analysis can provide guidance for fault diagnosis of bearings. A dynamic model for inter-shaft bearings is proposed based on Gupta's model with considering the movement of the outer ring. And the model is validated by experiments. Based on that, a faulty dynamic model of wear is proposed with considering the change of surface morphology of raceway and bearing clearance. Besides, a faulty dynamic model of localized defects is proposed by considering the change of the geometrical interaction and the direction of contact force. Then the vibration responses of inter-shaft bearing under different wear conditions are analyzed by this model. The results show that many random components appear in the vibration response for bearings with wear faults. For the bearing with compound faults as localized defect and wear, as wear goes more serious, the amplitude of vibration response becomes lager; the random components increase. The fault characteristics are not obvious.