Rod fastening rotor (RFR) is characterized by discontinuity of contact interface and unbalance of multiple disks. There are few researches that focus on unbalance effect including magnitude and phase difference on the nonlinear dynamic characteristics of RFR considering contact feature. A typical RFR model is proposed to investigate the nonlinear dynamic characteristics. The nonlinear motion governing equation considering unbalance excitation, nonlinear oil-film force and nonlinear contact characteristics between disks is derived by D’Alembert principle. The contact effects are simulated by bending spring with nonlinear stiffness. The research focuses on the effects of unbalance on the onset of low-frequency instability and nonlinear response of RFR. The obtained results evidently show the distinct phenomena brought about by the variations of unbalance, which confirms that unbalance magnitude and phase difference are critical parameters for the RFR system response. To restrain large amplitude of nonsynchronous vibration and retard the occurrence of instability, the unbalance magnitude of rotor is suggested to be kept at range from U5 to U6. Meaningfully, RFR can operate relatively well with small vibration and higher instability threshold when the residual unbalance between disks is controlled at an enough-reasonable unbalance phase difference. Phase difference adjustment can accomplish active balance. The total vibration and nonsynchronous components could be reduced, and onset speed of instability could be delayed effectively by using the proposed method, which is helpful for the dynamic design, assembly, balance and vibration control of such RFR.

中文翻译：

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考虑非线性接触的杆紧固转子-轴承系统中引起不平衡的非线性效应

杆紧固转子（RFR）的特点是接触界面不连续且多个磁盘不平衡。很少有研究关注具有接触特性的RFR非线性动力学特性的不平衡效应，包括幅度和相位差。提出了一个典型的RFR模型来研究非线性动力学特性。利用D'Alembert原理推导了考虑不平衡激励，非线性油膜力和盘间非线性接触特性的非线性运动控制方程。通过具有非线性刚度的弯曲弹簧来模拟接触效果。该研究集中于不平衡对RFR低频不稳定和非线性响应的影响。获得的结果显然显示了由不平衡变化引起的独特现象，这证实了不平衡幅度和相位差是RFR系统响应的关键参数。为了抑制大幅度的非同步振动并阻止不稳定性的发生，建议将转子的不平衡量保持在U5至U6的范围内。有意义的是，当将磁盘之间的剩余不平衡控制在足够合理的不平衡相位差时，RFR可以在较小的振动和较高的不稳定阈值下相对良好地运行。相位差调整可以实现主动平衡。利用该方法可以减少总的振动和非同步分量，有效地延迟了失稳的开始速度，