The effect of external load on multi-point contact transitions of three-point angular contact ball bearing

As a critical supporting component of aero-engine main shafts, the three-point angular contact ball bearing (TPACBB) is subjected to complex external loads, leading to time-varying contact characteristics that significantly influence its dynamic behavior and service life. This study establishes a universal, nonlinear, multi-degree-of-freedom dynamic model applicable to TPACBB. It employs the Lankarani-Nikravesh model for more accurate contact force calculation and comprehensively accounts for the interactions among the balls, cage, raceways, and lubricant. The relationship between axial/radial loads and multi-point contact states is investigated, and the dynamic performance under different contact conditions is analyzed. Additionally, the critical load ratio inducing multi-point contact variations is determined under varying loading conditions and structural parameters. The results reveal that the critical axial-to-radial load ratio governing the transition between three-point and two-point contact depends on the bearing's structural parameters. Specifically, the shim angle exhibits a positive correlation with the critical load ratio, whereas the inner raceway groove radius demonstrates a negative correlation. This research provides valuable insights for the structural optimization and fault diagnosis of TPACBB.