Influence of eccentric force and roller failure on vibration response of slewing bearing

Slewing bearings are important components in heavy-duty machinery, with their failure mechanisms critically impacting operational reliability. Firstly, considering the coupling effect of roller defects and tilting of inner ring, a three-dimensional dynamics model is developed. And the nonlinear vibration equation with time-varying contact stiffness is constructed based on Hertz contact theory. Then the defect-roller dynamic collision process is characterized by the introduction of the defect roller motion trajectory function. Moreover, the fourth-order Runge–Kutta method is used to solve the vibration response of the system, emphasizing on analyzing the dynamic coupling mechanism of roller defect size, eccentric load angle, and contact force. Finally, a slewing bearing experiment platform is built to verify the simulation results. The changes in stiffness and intrinsic frequency of the slewing bearing are measured by the eccentric load under different defect sizes. Time-domain analysis reveals defect size-dependent amplitude characteristics, with a peak increase of 42.6% observed. Spectral analysis revealed distinct mf o ± nf r modulation patterns (fundamental frequency error ≤ 7.86%). The multiparameter coupling model proposed in this study reveals the mapping law of defect size-vibration response under eccentric load condition. It provides a theoretical basis for the fault diagnosis of slewing bearings.