The presence of bearing defects significantly impacts the stable operation of rotating machinery, necessitating timely diagnosis of such faults. Understanding the fault mechanism serves as a theoretical foundation for fault diagnosis. As such, it is imperative to prioritize the study of vibration characteristics in rotor-casing systems affected by bearing faults. Given that rotor unbalance has the potential to modify bearing load zones and introduce a phase difference between defect locations and unbalanced forces, it can potentially impact the dynamic characteristics of systems with bearing defects. Moreover, the diverse displacement excitation functions of defects can also directly influence the system vibration. In this paper, a dynamic model of a single/dual rotor-pedestal-casing system with bearing defects is established using the finite element method and lumped parameter method. The accuracy of the bearing defect model is verified through a rotor dynamic experiment. The load characteristics of the bearing are firstly analyzed. Then, the impact of defect location, speed, and phase difference on the time domain and frequency domain characteristics of vibration response in a single rotor system is investigated. The independence of discrete time steps is verified when the rolling element passes through the defect region. Meanwhile, the effects of rectangular, triangular, half-sine displacement excitation functions and the displacement excitation function associated with the spatial position of the rolling element on system vibration are compared. Additionally, the defect characteristics of the intermediate bearing’s inner and outer raceways are also subjected to analysis. The results indicate that rotor unbalance significantly influences the vibration response of the faulty bearing, while the spectrum characteristics of the system remain consistent under various defect displacement excitations. However, notable distinctions can be observed in terms of time domain characteristics. Compared to high speeds, low speeds are more conducive to the fault diagnosis in the outer and inner rings of the intermediate bearing.

中文翻译：

---

具有局部轴承缺陷的单/双转子-轴承-壳体系统的振动特性研究


轴承缺陷的存在会显著影响旋转机械的稳定运行，因此需要及时诊断此类故障。了解故障机理是故障诊断的理论基础。因此，必须优先研究受轴承故障影响的转子壳体系统的振动特性。鉴于转子不平衡量有可能改变轴承载荷区，并在缺陷位置和不平衡力之间引入相位差，因此它可能会影响具有轴承缺陷的系统的动态特性。此外，缺陷的不同位移激励函数也可以直接影响系统振动。本文采用有限元法和集总参数法建立了具有轴承缺陷的单/双转子-基座-壳体系统的动力学模型。通过转子动力学实验验证了轴承缺陷模型的准确性。首先分析了轴承的载荷特性。然后，研究了缺陷位置、速度和相位差对单转子系统中振动响应的时域和频域特性的影响。当滚动体通过缺陷区域时，验证离散时间步长的独立性。同时，比较了矩形、三角形、半正弦位移激励函数和与滚动体空间位置相关的位移激励函数对系统振动的影响。此外，还分析了中间轴承的内滚道和外滚道的缺陷特性。 结果表明，转子不平衡对故障轴承的振动响应有显著影响，而系统频谱特性在各种缺陷位移激励下保持一致。但是，在时域特性方面可以观察到显著差异。与高速相比，低速更有利于中间轴承外圈和内圈的故障诊断。