Influence of elliptical truncation on the raceway in a four-point contact pitching bearing

As a key component of a wind turbine, the pitch bearing suffers from harsh operating conditions and have to endure complex loads. Due to a large contact angle or load, harmful elliptical truncation may result in stress concentration. However, the influence of elliptical truncation on the performance of the raceway has been rarely studied. This paper investigates the effects of elliptical truncation rates on the raceway surface and subsurface stresses under various loads in a four-point contact pitch bearing. A raceway-ball contact finite element model (FEM) considering raceway hardening is established. The results of a raceway contact experiment which utilizes pressure sensitive films demonstrates the correctness of the FEM. The weakening effect of elliptical truncation on raceway fatigue life is analyzed through three methods. The findings provide an insight for controlling elliptical truncation rate in bearing design and fatigue life assessment to help avoiding raceway crushing and early fatigue failure.