Dynamic modelling of angular contact ball bearings with local defects under EHL considering impact force

In order to precisely analyze the operating status of angular contact ball bearings (ACBBs) with local defects and response to the impact force caused by bearing lubrication and defects in the traditional model, a dynamic model of ACBBs with local defects considering impact force under elastohydrodynamic lubrication (EHL) conditions was proposed. Firstly, an EHL model for defective bearings considering spin was established, and the oil film thickness and oil film stiffness of the defective bearings were calculated. Time-varying displacement excitation model and time-varying stiffness model for local defects in ACBBs were presented. On this basis, an instantaneous impact force function related to defect size and bearing speed was established. Secondly, based on Hertz contact theory and impact force function, a dynamic calculation method for ACBBs with local defects on the outer ring was proposed. Finally, the vibration characteristics of ball bearings with faults were investigated, and the influence of different parameters on the dynamic response of the bearings was analyzed through experiments. The calculation results show that under lubrication conditions, the impact force on the vibration of the bearing is significantly weakened. With the increase in defect size and load, the frequency of bearing fault characteristics remains unchanged, but its amplitude increases. As the bearing speed increases, the characteristic frequency and amplitude of bearing faults increase, providing a powerful basis for fault diagnosis and maintenance of rolling bearings.