单跨双盘裂纹转子-轴承的动力学特性研究

Dynamic Study on a Single-span Double-disc Rotor-Bearing System with a Crack

在考虑裂纹的时变刚度和综合模型的基础上,采用有限元法建立了左侧为弹性支承、右侧为非线性油膜力 支承的单跨双盘裂纹转子系统的动力学模型和两端均为弹性支承的裂纹转子系统模型,并利用4阶Runge-Kutta方法 进行求解,研究裂纹位置、裂纹深度、转速和裂纹轴刚度变化量对转子系统动力学响应的影响,并对2个模型的动力学 特性进行对比分析。研究结果表明:在转速、裂纹深度和裂纹轴刚度变化量相同的条件下,裂纹位于转子左侧轴段的 振动总是比裂纹位于转子中间轴段的振动剧烈;当转速较小时,无论裂纹位于转子左侧还是中间轴段,系统的振动响 应主要是由裂纹引起的,频谱图上会出现高频分量;当转速较高时,系统的振动响应主要是由偏心量引起的。研究结 果可为系统故障诊断提供依据。

Based on the time-varying stiffness and the comprehensive model of the crack,the finite element method is used to establish two dynamic models of a cracked single-span double-disc rotor system,namely the system with the elastic bearing support at the left end and the nonlinear oil film bearing support at the right end and the system with the elastic supports at both ends.The fourth-order Runge-Kutta method is used to solve the models so as to study the effects of the crack location,the crack depth,the rotational speed and the variable quantity of the stiffness on the dynamic response of the cracked rotor system.The dynamic characteristics of the two models are mutually compared and analyzed.The results show that the vibration of the system when the crack is in the left shaft section of the rotor is always more severe than that of the system when the crack is in the middle section of the rotor under the same conditions of the crack depth,the rotational speed and the variable quantity of the stiffness.When the rotational velocity of the rotor is small,the vibration response of the system is mainly caused by the crack and the high-frequency component will appear on the spectrogram no matter whether the crack is on the left side or on the intermediate shaft section of the rotor.When the rotational velocity of the rotor is high,the vibration response of the system is mainly caused by the eccentricity.The results may provide the basis for the system fault diagnosis.