Damage characterisation and root cause analysis of wind turbine pitch bearings

Blade pitch bearings of large scale wind turbines control the individual blades in order to maximise power generation at low wind speeds and to prevent turbine damages under high winds. The reliability of blade pitch bearings is of critical importance to operation and energy production, especially for offshore wind turbines as any blade pitch bearing failures and replacements can be extremely costly.

This project will carry out a thorough failure investigation and root cause analysis of pitch bearings of a multi-megawatt scale wind turbine by metallurgical investigation and computational modelling. A failed pitch bearing raceway will be destructively investigated to characterise the surface and subsurface damages using optical microscopy (OM) and scanning electron microscopy (SEM), to identify typical bearing failure modes and to interpret their root causes. Finite Element modelling of bearing raceway and ball contacts will be developed to investigate contact pressure variations and raceway deformation during typical operation conditions of turbine blades. The understanding of pitch bearing failure modes and root causes obtained in this project will lead to new design technologies of pitch bearings for future offshore wind turbines.