基础运动诱发的转子-轴承系统非线性动力学特性研究

Most of current studies concentrated mainly on rotors with fixed bases. However, the base of rotor system might be time-dependent and moving. Such systems are very common in practice. Powertrains, which are installed in aircrafts, ships, automobiles, gas turbines, wind turbines and other transportation or power systems, are typical examples of rotors on moving bases. The system might undergo large time-varying linear as well as angular displacements. Excitations of moving base will not only cause external force excitations, but also gyroscopic and stiffness excitations to the rotor-bearing system. Both the external and internal excitations induced by the moving bases would bring significant impacts on the system's dynamic characteristics and operating reliability. Due to the problems in current studies (including: inaccurate modelling, incomplete considerations of nonlinear factors, unclear fault mechanism and insufficient experimental studies), the dynamic behaviors of base excited rotor system are studied theoretically and experimentally in the project. Considering the arbitrary base motions with six degrees of freedom, various nonlinear factors and typical rotor faults, a comprehensive dynamic finite element model is established. Both the steady-state and transient dynamic responses in time domain, frequency domain and time-frequency domain, are obtained utilized the theoretical and numerical methods. The mechanisms of typical faults in rotor systems are investigated, and the indications corresponding to different faults are pointed out. Based on the test rig of rotor-base system with multiple degrees of freedom, both the dynamic model and numerical results are verified accordingly.

传统转子动力学通常认为基础是固定的。但是，对于机动飞行的飞机、行进中的船舶和汽车、地震冲击作用下的燃气轮机、柔性支承下的风力发电机组等，这些机械装备的转子系统将具有运动的基础。基础运动不仅产生多频外载荷激励，而且也使得转子系统出现附加刚度、陀螺和阻尼等时变内部激励。由基础运动所引起的多频内、外激励将对高速转子系统的动态特性及其工作可靠性产生重要影响。针对现有研究存在的"模型不完备、转子非线性因素考虑不全面、故障转子特征不明晰、实验研究较匮乏"等突出问题，本课题拟从理论分析和实验测试两方面系统深入研究基础运动转子-轴承系统动态特性，建立综合考虑六自由度基础运动、多种转子非线性因素、转子典型故障的有限元时变参数分析模型，采用理论和数值方法获得稳态和瞬态振动响应的时域、频域和时频特性，揭示基础运动转子典型故障的动力学特征，并通过多自由度运动基础-转子实验平台进行测试验证。

针对基础运动下转子-轴承系统，综合运用理论分析、数值仿真和实验测试三种手段，系统深入的研究基础运动诱发的转子-轴承系统非线性动力学行为，揭示基础运动转子典型故障的动力学特征。围绕项目研究目标，开展了较为系统深入的研究：首先，建立了六自由度基础运动柔性转子-轴承系统有限元模型，分析了因基础周期性运动引起的转子系统的失稳现象，计算了系统非线性动态响应，并以基础运动的行星齿轮为例，说明了周期性基础运动对系统均载特性的影响；其次，建立了能够准确描述滚动轴承时变接触特性的非线性迭代模型，分析了轴承非线性赫兹接触对转子系统动态响应的影响机制，并探讨了动载作用下滚动轴承滚动体的打滑规律；进而，建立了考虑行星轮轴承局部故障的行星齿轮-转子-轴承系统动力学模型，分析了内圈和外圈局部故障对系统振动响应的影响规律，总结了不同故障所对应的故障特征；最后，搭建能够模拟不同基础运动形式的转子-轴承系统试验台，试验研究系统振动响应的时域和频域特征，并进行对比分析，验证了理论模型的准确性。上述成果已发表论文21篇，其中SCI收录论文18篇，EI收录论文3篇。项目研究成果对于基础运动转子-轴承系统的设计和状态监控具有重要的参考价值。