基于显式有限元的转子不平衡与轴承故障耦合分析

Analysis on Coupling Between Rotor Unbalance and Bearing Fault Based on Explicit Finite Element

为分析转子不平衡与轴承故障耦合振动特征及产生机理,在对转子不平衡与轴承故障耦合状态下受力分析的基础上,基于虚位移原理的增广拉格朗日法建立轴承运动控制方程,运用LS-DYNA建立转子-轴承系统二维显式动力学有限元模型,分析了故障耦合状态下轴承振动加速度、转子轴心运动轨迹,探明了转子不平衡-轴承缺陷耦合故障冲击响应特征及转子轴心运动轨迹突变机理,并通过试验进行了验证。结果表明:转子不平衡与轴承外圈故障耦合状态下,轴承座测点位置故障特征频率被转频调制,冲击幅值随转频变化;转子轴心轨迹呈椭圆形,且缺陷位于轴承承载区时,转子轴心轨迹存在突变。

In order to analyze the vibration characteristics and mechanism of coupling between rotor unbalance and bearing fault,based on force analysis under coupling state of rotor unbalance and bearing fault,the motion control equation of the bearing is established based on virtual displacement principle of augmented Lagrange method,the two-dimensional explicit dynamic finite element model of rotor-bearing system is established by LS-DYNA.The vibration acceleration of the bearing and the motion trajectory of rotor axis under fault coupling state are analyzed.The shock response characteristics of rotor unbalance-bearing defect coupling fault and the mutation mechanism of motion trajectory of rotor axis are found out,which are verified by experiments.The results show that the fault characteristic frequency at measuring point position of housing is modulated by rotational frequency and the impact amplitude varies with rotational frequency under coupling state of rotor unbalance and bearing outer ring fault.The trajectory of rotor axis is elliptic,and the trajectory of rotor axis has a sudden change when the defect is located at loaded zone of the bearing.