Hysteretic damping model for the dynamic response in four-point contact slewing bearings

Four-point contact slewing bearings are crucial in orientation applications, where damping significantly influences system vibrations. To correlate experimentally their minimum damping capacity through sine tests, this study develops and evaluates three hysteretic damping models representing material hysteresis due to hertzian ball-raceway deformation. Unlike existing models, these account for preloaded contacts while considering also the potential contact loss between balls and raceways. To achieve this, the material loss factor is used as a representative parameter of the material dissipation capacity, adapted to consider contact loss in preloaded bearings under vibration. The damping models are integrated into a mechanistic model that simulates the axial dynamic response of the bearing and validated through finite element simulations, achieving satisfactory correlation. Consequently, this study provides parametric expressions for minimum damping capacity of these bearings as a function of ball diameter, contact conformity, and material loss factor, with the latter to be correlated experimentally through sine tests.