Vibration Characteristics of Angular Contact Ball Bearings with Local Defects Considering Friction

Rolling bearings play a crucial role in mechanical systems, offering benefits such as reduced noise and enhanced transmission efficiency. They find extensive application in rotating machinery. Despite their durability, rolling bearings are often subjected to challenging conditions for extended periods, and the surface of part is prone to fatigue spalling, pitting or even glue and other local defects, which will affect the operating performance of bearing and the reliability of mechanical equipment.So that, it is crucial to investigate the dynamic properties of ACBB with local defects. In order to provide more detailed description of the dynamic behavior of ACBB with local defects during actual operation, a comprehensive stiffness model for ACBB regarding the effect of elastohydrodynamic lubrication was developed. The oil film thickness contemplating spin motion was combined with the contact deformation, and the sliding friction was introduced, and the dynamic model of ACBB with local defects was introduced. The vibration attributes of the ball bearing with local faults were studied, taking sliding friction into account. The impact of various parameters on the dynamic response of the bearing was examined. The outcome showed: as the rotational speed increases, the central film thickness at the inner and outer rings of ACBB increased, and the minimum oil film thickness also increased. Considering spin motion, the minimum oil film thickness was lower than that of condition without considering spin. As the speed increased, both the inner and outer ring oil film stiffness decreased. When considering the spin condition, the oil film stiffness increased, which led to a slightly increase in the total contact deformation and friction force of the bearing. When the rotational speed was fixed and the sliding friction force increased, the fault characteristic frequency and harmonic frequency of the bearing remained unchanged, but the vibration response amplitude would significantly increase, and the amplitudes of the second and third harmonic generation also increased significantly. By comparing the amplitude of vibration response signals, it could be concluded that the occurrence of sliding friction would exacerbate the vibration of local defect ACBB, thereby having adverse effected on the entire mechanical system. Meanwhile, as sliding friction increased, bearing vibration intensifies, accelerating bearing failure. Moreover, as the size of the defect increased, the amplitude of the bearing's fault characteristic frequency also increased, while the frequency value itself remained constant. As the load increased, the fault characteristic frequency and its harmonic frequency amplitude showed a slow increasing trend, while its frequency value did not change with the change of load. Finally, In conclusion, with the increase in spindle speed, the fault characteristic frequency of the bearing likewise increased, along with variations in amplitude. This was because during bearing operation, the rolling experience periodically passed through the defect area, which generates vibration response, and the fault frequency is related to the speed and bearing geometric parameters. These research findings were of great significance for in-depth understanding of the dynamic behavior of ACBB with local defects and evaluating their safety and reliability. Future research could further explore the impact of other factors on the dynamic response of bearings, such as temperature and lubricant viscosity.