Research on Mechanism of Fatigue Life Enhancement in Ball Bearings by Residual Compressive Stress.

While the beneficial effect of residual compressive stress (RCS) on rolling bearing fatigue life is empirically well-established, the underlying mechanisms, particularly its influence on the subsurface stress field responsible for fatigue initiation, remain inadequately explored. This study employs a sophisticated finite element (FE) model of a ball-raceway contact, which incorporates a depth-dependent gradient of RCS, to elucidate the underlying mechanisms. The results demonstrate that RCS not only reduces the contact stress at the interface but also fundamentally alters the subsurface stress field by shifting the location of the maximum shear stress to a greater depth and reducing its inclination angle. These changes collectively delay crack initiation and propagation, explaining the observed enhancement in fatigue life. Furthermore, the study demonstrates that the beneficial effect of RCS is depth-dependent and persists significantly even under high-friction conditions.