Three-dimensional fretting and sliding contact model in planetary gear system: Theoretical analysis and experiments

The failure of the interference fit between the planetary gear and the bearing outer rings in planetary gear systems has received increasing attention from researchers. In this study, a three-dimensional model for determining the fretting and sliding contacts between planetary gears and these outer rings is presented. A three-dimensional fretting numerical model under oblique forces was established to investigate the fretting contact between planetary gears and bearings, and an experiment was conducted to study the relative sliding between them. The results showed that if the torque generated by the difference between two meshing forces exceeded the limit torque of the interference fit, overall relative sliding would occur. Otherwise, fretting contact would occur in some regions of the interference fit surface under oblique forces. The relative sliding between the planetary gear and outer rings of the bearings can be reproduced experimentally; the relative sliding value decreased with an increase in the size of the interference fit.