The current work experimentally explores and then theoretically examines the lateral vibrations of an unbalanced Jeffcott rotor-system working at several unbalance conditions. To this end, three conditions of eccentric masses are considered by using a Bently Nevada RK-4 rotor kit. Measurements of the steady-state as well as the startup data at rigid and flexible rotor states are captured by conducting a setup that mimics the vibration monitoring industrial practices. The linear governing equation of the considered rotor is extracted by adopting the Lagrange method on the basis of rigid rotor assumptions to theoretically predict the lateral vibrations. The dynamic features of the rotor system such as the linearized bearing induced stiffness are exclusively acquired from startup data. It is demonstrated that, with an error of less than 5%, the proposed two-degrees-of-freedom model can predict the flexural vibrations at rigid condition. While at flexible condition, it fails to accurately predict the dynamic response. In contrast to the other works where nonlinear mathematical models with some complexities are proposed to mathematically model the real systems, the present study illustrates the applicability of employing simple models to predict the dynamic response of a real rotor-system with an acceptable accuracy.

中文翻译：

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不平衡Jeffcott转子横向振动的实验和理论研究。

当前的工作是通过实验探索，然后在理论上检查在几个不平衡条件下工作的不平衡Jeffcott转子系统的横向振动。为此，使用Bently Nevada RK-4转子套件考虑了三种偏心质量条件。通过执行模拟振动监测工业实践的设置，可以捕获在刚性和柔性转子状态下的稳态以及启动数据的测量结果。在刚性转子假设的基础上，采用拉格朗日方法提取考虑的转子的线性控制方程，以从理论上预测侧向振动。转子系统的动态特征，例如线性轴承引起的刚度，只能从启动数据中获取。结果表明，误差小于5％，所提出的两自由度模型可以预测刚性条件下的弯曲振动。在灵活的条件下，它无法准确预测动态响应。与提出具有复杂性的非线性数学模型对实际系统进行数学建模的其他工作相反，本研究说明了采用简单模型以可接受的精度预测实际转子系统的动态响应的适用性。