Implementing raceway damage in a finite-element blade bearing model

Abstract. During the operation of large slewing bearings, material outbreaks on the raceway due to rolling contact fatigue can occur. These local raceway damages can lead to unloaded rolling elements because of changes in the surface geometry and with that alter the internal load distribution and thus significantly affect the remaining service life of the bearing. While finite-element (FE) models are widely used to determine load distributions, the influence of such damage on the global bearing behavior has not yet been sufficiently addressed. In this work, a methodology to implement raceway damage in a finite-element model of a downscaled double-row four-point contact ball blade bearing is presented. To ensure computational efficiency, the ball–raceway interactions are represented by nonlinear spring elements, which are extended by pretension elements to introduce local gaps corresponding to measured damage depths. The damage progression on the raceways of rolling contact fatigue tests is documented and considered in the FE simulations. The resulting deformation behavior is validated by comparing simulation and experimental. strain gauge data on the bearing outer rings. The comparison shows that the model can reproduce the characteristic changes in the bearing behavior caused by increasing damage, with good agreement for most investigated states. The simulations further reveal that local material removal leads to pronounced changes in the global load distribution, including load increases on adjacent balls. Bearing life calculations based on the altered global load distributions indicate a negative influence on the service life. The results highlight the importance of considering damage-induced load redistribution when assessing the condition and residual life of wind turbine blade bearings in operation.