含双频时变滚动轴承刚度的转子-轴承系统响应特征研究

Response characteristics of a rotor-bearing system with double-frequency time-varying bearing stiffness

考虑有限数目滚动体和转子不平衡力引起的滚动轴承刚度的周期时变性,建立了含双频时变滚动轴承刚度的三自由度转子-轴承系统动力学模型。以单频参数激励系统响应的频率分布规律为参照,指出了含双频时变参数的动力学系统其响应的频率构成规律:双频参数激励系统自由响应中出现的频率是系统等效固有频率分别和参数频率的组合,以及等效固有频率同时和两个参数频率的组合;强迫响应中的频率除了包含自由响应中的频率成分之外,还包含外激励频率分别和两个参数频率的组合,以及其同时和两个参数频率的组合。在转子-滚动轴承系统响应中出现的倍频响应、参数频率及其倍频对应的频率成分,可以通过该分析给出合理的解释。该结论有助于更深入地理解多频参数激励系统响应的频域特征,为变参数旋转机械系统故障诊断中的频率成分识别提供了参考。

Considering periodic time-varying stiffness of ball-bearings due to finite balls and a rotor, s unbalanced force, a 3-DOF rotor-bearing system was set up. Referring to the response frequency distribution law of a single-frequency parametrically excited system, the response frequency constitution law of a double-frequency parametrically excited system was formed. The latter was that the frequencies appearing in the system, s free responses are combinations of the sytem, s equivalent natural frequencies and the two parametric ones, respectively and combinations of the system ^ s equivalent natural frequencies and the two parametric ones simultaneously ; the frequencies appearing in the system ’ s forced responses include not only those appearing in the system , s free responses, but also combinations of the excitation frequencies and the two parametric ones, respectively and combinations of the excitation frequencies and the two parametric ones simultaneously. In addition, the double-frequency response and response frequency components corresponding to parametric frequencies and their double ones appearing in the responses of the rotor-bearing system were explained reasonably through deep analyses here. The conclusions obtained here were helpful to deeply understandingresponse characteristics in frequency-domain of a muti-frequency parametrically excited system, they also provided a reference for frequency component identification of faults appearing in a rotating machinery system with time-varying parameters.