Research on Dynamic Characteristics and Fault Diagnosis of Outer Race Defects in Rolling Bearings Considering EHL and Centrifugal Effects

This paper proposes a dynamic model incorporating centrifugal forces and elastohydrodynamic lubrication (EHL) to analyze the vibration characteristics of high-speed rolling bearings with localized outer raceway defects. A four-degree-of-freedom (4-DOF) motion equation is established using Hertzian contact theory and isothermal EHL equations. Numerical solutions incorporating defect-induced time-varying displacement excitations are experimentally and theoretically validated. Results confirm the oil film’s vibration-damping effect, reducing peak acceleration by 11.8% and the root-mean-square (RMS) value by 3.7% compared to dry contact conditions. Higher rotational speeds thin the oil film and reduce comprehensive stiffness, amplifying vibration and impact intensity without altering fault characteristic frequencies, which remain stable with a relative error within 0.5%. As the defect size increases, RMS and peak values rise monotonically, with the RMS acceleration increasing by 69.5% (from 0.6102 m/s2 to 1.0344 m/s2) as the outer race defect expands from 0.2 mm to 0.8 mm, while kurtosis peaks and subsequently declines. The dual-impact phenomenon is most prominent under low rotational speed and large defect conditions, providing a basis for a a quantitative fault diagnosis strategy to invert defect size from dual-impact time intervals is proposed and experimentally validated, yielding an inversion error of less than 2% under such favorable conditions. While this inversion method is condition-dependent—with its precision degrading under increased speeds and micro-defect scenarios—it provides an accurate and reliable quantitative tool within its applicable boundaries. The developed dynamic model and multi-index diagnostic approach provide a theoretical basis and practical reference for fault diagnosis, condition monitoring and quantitative defect identification of rotating machinery.