In order to understand the mechanism of fixed-point rub-impact in aero-engine, a dual-rotor system with inter-shaft bearing able to describe the mechanical vibration caused by unbalance and fixed-point rub-impact is developed in this paper. Firstly, a finite element (FE) model of the dual-rotor based on Timoshenko beam element and disk element is proposed, in which the effects of gyroscopic moments, rotary inertias, bending and shear deformations are taken into account. A rub-impact model is developed to derive the rubbing force between the rotor and fixed limiter, in which the softening characteristics of coating painted in casing is fully taken into account. Moreover, the Coulomb model is applied to describe the frictional behaviors. Secondly, the governing equations to describe the motion of the dual-rotor system with rub-impact are solved numerically by the Runge-Kutta method, and the dynamic characteristics are investigated by 3D water-fall plots and frequency spectrum. Combined harmonic frequency, whirling frequency and rotational frequency components of dual rotors are observed. Finally, the experiments of fixed-point rub-impact are performed on a dual-rotor test bench. Good agreement between the theoretical and experimental results shows the accuracy of the dual-rotor FE model and rub-impact model. The results indicate that (1) first backward whirling and forward whirling are excited under the influence of unbalance force; (2) several combination frequency components and second backward whirling and forward whirling frequency components are presented under fixed-point rubbing condition.

中文翻译：

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摩擦冲击对双转子系统振动响应的影响——理论与实验研究

为了理解航空发动机定点摩擦的机理，本文开发了一种带有轴间轴承的双转子系统，能够描述由不平衡和定点摩擦引起的机械振动。首先，提出了一种基于Timoshenko梁单元和圆盘单元的双旋翼有限元（FE）模型，其中考虑了陀螺力矩、转动惯量、弯曲和剪切变形的影响。建立了摩擦模型来推导转子与固定限位器之间的摩擦力，其中充分考虑了套管涂漆的软化特性。此外，库仑模型用于描述摩擦行为。第二，用Runge-Kutta方法数值求解了描述摩擦双转子系统运动的控制方程，并通过3D瀑布图和频谱研究了动力学特性。观察到双转子的组合谐波频率、旋转频率和旋转频率分量。最后，在双转子试验台上进行了定点摩擦试验。理论和实验结果之间的良好一致性表明双转子有限元模型和摩擦模型的准确性。结果表明：（1）在不平衡力的影响下激发了先向后旋和前向旋涡；