轴承-转子系统在基础运动作用时的非线性分析

Nonlinear analysis of bearing-rotor system with base movements

轴承-转子系统的非线性特性及其在基础运动作用时的响应,是离心机设备设计阶段必须考虑的。本文使用简化的多自由度转子模型进行模拟分析,运动方程考虑了非线性的油膜润滑轴承模型。应用自适应时间步长的Runge-Kutta-Felburg法求解微分运动方程组,将人造的正弦波加速度作为基础运动输入系统,使用Poincaré图、分岔图和瀑布图分别考察了垂直放置转子在有无基础运动作用时的动力学性质。快速傅里叶变换在频域内揭示了转动频率与基础振动频率之间的组合共振现象。计算的结果不仅给出了泵转子自身的非线性性质,也展示了泵转子在基础运动作用时的组合共振。

Nonlinear dynamics characteristics of bearing-rotor system are necessary to be investigated for centrifugal machines in design stage as well as nonlinear response of the system subjected to base move-ments. The simplified model with multi-freedom-degree is applied to perform the numerical simulation. The nonlinear model of oil film bearing is taken into account in motion equations. The adaptive step method of Runge-Kutta-Felburg is applied to solve the differential equations. The artificial sine wave acceleration is considered as base movement input to the system. The Poincaré maps, bifurcation diagrams and cascade maps are used to investigate the dynamics of vertical rotor system. Combination resonance behavior which due to both rotational speed and base movement is discovered by the Fast Fourier Transform. The results yield not only nonlinear characteristics of the pump rotor, but also combination resonance under base movements.