| A “three-body” elastic-plastic finite element model of 3-D axisymmetric pure rolling contact has been developed to study the effects of a spherical dent defect. The model represents a deformable sphere rolling on a dented semi-infinite half-space. It consists of a 400 μm diameter rigid indenter, an elastic-plastic half-space, and a 12,700 μm diameter deformable sphere. The rigid indenter is used to place a spherical dent defect on the surface of the half-space. Rolling contact simulation over the dent defect is performed by translating the deformable sphere vertically downward and upward to complete 1 contact cycle. The material model is an Armstrong-Fredericks type with nonlinear kinematic-hardening adjusted to match 52100 bearing steel tests by Hahn et al.; The finite element results are used to predict the location and plane of crack nucleation and fatigue life using several variants of the critical plane fatigue criterion. Crack nucleation is predicted radially inward from the maximum dent bump consistent with the first appearance of cracks reported by Dommarco et al, from 3 ball-rod rolling contact fatigue tests. Fatigue life prediction is seven and eleven times less than the average experimental crack initiation life for the Manson-Coffin total strain and Basquin's stress life methods, respectively, and greater by a factor of 21 for total strain adjusted with the Fatemi-Socie parameter. |
