转子-轴承系统小裂纹识别的HHT谱分析方法

HHT Spectrum Analysis Method for Identification of Small Cracks in Rotor-Bearing System

针对低转速工况下转子-轴承系统小裂纹识别难的问题,提出Hilbert-Huang变换谱和边际谱分析的方法。分别建立刚性支承及轴承支承的裂纹转子模型,比较二者频谱差异,并采用四阶Runge-Kutta法求解重力占优背景下裂纹转子-轴承系统动力学方程;对时域信号进行经验模态分解,提取其IMF分量,计算各IMF分量的HHT谱及边际谱,并对无裂纹和小裂纹情况进行分析。结果表明,对于受非线性油膜力影响的裂纹转子-轴承系统,HHT方法能够很好体现裂纹刚度随时间变化的过程;通过EMD方法分解出的IMF分量,在小裂纹、低转速下对裂纹的变化有很好的敏感性,能有效识别转子-轴承系统的小裂纹故障。

To address difficulties in identification of small cracks in the rotor-bearing system,this paper proposes the HHT spectrum and single-sided amplitude spectrum analysis method. The models of the cracked rotors with rigid support and bearing support are established respectively and their power spectrum differences are compared. Meanwhile,the fourth-order Runge-Kutta method is used to solve the dynamic equation of the cracked rotor-bearing system under the gravity dominant. The time-domain signals are decomposed by EMD and their IMF components are extracted. The HHT and single-sided amplitude spectrum of each IMF component are calculated and the conditions of no crack and small cracks are analyzed. The results show that HHT method can well reflect the process of crack stiffness changing with time for the cracked rotorbearing system affected by oil film force;the IMF component decomposed by EMD method is sensitive to the crack depth at small cracks and low rotating speeds,suggesting that the HHT analysis can effectively identify small crack faults in the rotor-bearing system.