Wind turbine (WT) blade pitch bearings use large slewing bearings to connect blades to the turbine hub, enabling independent rotation for optimized power generation and safety during high winds. These bearings undergo small-angle oscillatory motions under significant loads, resulting in wear damage such as fretting wear and false brinelling. Although double-row, eight-point contact ball bearings are commonly used, their complex rolling and sliding motions complicate wear prediction. Moreover, the mechanisms and variables causing wear in these bearings remain poorly understood.
This study investigates fretting wear in three-row roller bearings as an alternative design for WT blade pitch bearings. A finite element (FE) model is developed to analyse load distribution, employing non-linear spring models to improve simulation efficiency. Wear tests are performed using small- and medium-scale roller-on-plate configurations under various conditions, including contact pressure, oscillation amplitude, frequency, lubrication, and cycle numbers. Two different scaled FE models are developed to simulate wear severity under these conditions, with validation achieved by comparing experimental and simulated results. The findings emphasize the critical role of grease lubrication in reducing wear and maintaining rolling motion, while higher loads and oscillation amplitudes significantly increase wear. FE simulations show that higher accumulated dissipated frictional energy density at roller contact areas leads to greater wear depth. Effective strategies for reducing wear include minimizing load, controlling oscillation amplitude, and applying appropriate grease lubricants. The novelty of this study lies in investigation of using three-row roller bearings as an alternative WT blade pitch bearing design, testing under approximately similar operating conditions of WT blade pitch bearings.
However, limitations include the inability to conduct long-cycle tests or simulate extreme conditions due to equipment limitations. Future research can explore thermal energy dissipation, lubricant effects, and extended test conditions, such as higher loads and oscillation frequencies.
