中文摘要：

研究了在非稳态油膜力作用下非线性刚度转子系统发生碰摩时的振动问题。建立了非稳态油膜力作用的非线性刚度转子一轴承系统碰摩模型，应用数值分析的方法对其进行研究。通过Poincare截面图、轴心轨迹图、波形图和频谱图，直观地显示了系统在某些参数域中的运动状态。发现了由于油膜力作用出现油膜涡动和反向涡动现象以及倍周期分岔、概周期和混沌等复杂的动力学行为。数值分析结果为该类转子一轴承系统的设计和运行状态控制提供了理论参考。

英文摘要：

The problem of rotor-bearing with nonlinear stiffness under an unsteady oil-film force was studied when rub-impact happened. A rub-impact rotor model with unsteady oil-film force was built. Applying the means of numerical integral method, we acquired the bifurcation diagrams, the Poincare maps, the shaft centerline orbit and the frequency spectrums of the system in some typical parameter regions. The results show that exists abundant nonlinear dynamics behaviour ,such as periodic solution, quasi-periodic and chaotic motions and so on. At the same time, the phenomena of oil-film whirl and diverging backward whirl is discovered when the rubbing happens. This study provides the theoretical foundation for design and fault diagnosis of a rotor system.