As new energy vehicle drive motors develop toward higher rotational speeds and power levels, a more comprehensive characterization of the geometric condition of high-speed ball bearings is increasingly required, while conventional single-section measurements have difficulty capturing continuous axial geometric variations. To characterize continuous axial geometric variations in high-speed ball bearings for new energy vehicle drive motors and explore whether these variations exhibit trends consistent with vibration responses, four typical bearing models were investigated using X-ray computed tomography (XCT), reconstruction, and dimensional extraction. Equivalent inner and outer diameters were obtained from consecutive sections within the selected axial profile segment. The mean values of the equivalent inner and outer diameters were used to represent the dimensional level, while the standard deviation and range were used to quantify the axial fluctuations. The results showed that the equivalent inner and outer diameters of different bearing samples exhibited different degrees of axial variation within the selected axial profile segments. Meanwhile, the mean equivalent inner and outer diameters measured by XCT differed from the corresponding nominal dimensions. Further comparison showed that, within the current sample set, no stable correspondence was observed between the axial variation descriptors of the XCT-derived equivalent inner and outer diameters and the vibration test results. XCT can nondestructively acquire geometric information from consecutive axial sections and quantitatively characterize equivalent inner and outer diameter fluctuations, complementing single-section roundness measurement and providing theoretical guidance for surface-quality evaluation and manufacturing-process improvement.

To investigate the contact mechanical performance of helicopter main gearbox rotor shaft bearings under a complex load spectrum, this study focuses on the contact stress and load-carrying characteristics of bearings operating under high-speed and heavy-load conditions. Based on the rotor shaft system of a helicopter main gearbox and Hertzian contact theory, quasi-static analyses were performed on four tapered roller bearings and one cylindrical roller bearing mounted on the shaft system conducted in Romax. The results indicate that the maximum contact stresses of the bearings do not exhibit sustained high-stress states under most operating conditions. The peak-stress conditions account for only extremely small time proportions in limited cases, namely 0.003429% and 0.025%. The contact stresses on both the inner and outer raceways exhibit a non-uniform distribution along the roller length, with local peak values appearing near the highly loaded roller-raceway contact regions. This suggests that during the design process of the helicopter main gearbox rotor shaft, special attention should be given to this region. The present results provide a theoretical basis for subsequent life-index verification and offer an effective analytical method for the design and validation of such critical components.