Rolling contact fatigue calculation of a three-row roller pitch bearing in a wind turbine

Abstract. Rolling contact fatigue calculations of wind turbine pitch bearings have to consider the oscillating operation and the complex, dynamic load distribution in the bearing. The present work proposes a methodology to calculate the life of a pitch bearing that is a roller bearing, specifically a three-row roller bearing. Previous publications in this field have discussed the life calculation of ball pitch bearings. Methodologies applicable to any pitch rolling bearing are partly improved upon in the present work. Several aspects not applicable to roller bearings are re-thought. In comparison to ball bearings, the calculation of roller bearings adds another level of complexity, since they have a long contact which is typically discretized if strong deformation is present, leading to significantly more degrees of freedom. Exemplary calculations are carried out using an extensively validated FE model of a three-row roller bearing of a wind turbine. For this paper, the bearing is modified slightly. The results of the life calculation are put in relation to an accelerated fatigue test on a pitch bearing test rig. Since some of the results can nonetheless not be shown for reasons of confidentiality, the focus of this paper is on the methodology used.