This project proposal is focused on investigating subsurface cracks in wind
turbine bearings called White Etching Cracks (WEC), which is probably the
single most critical and least understood failure mode experienced in wind
turbines. This project can be carried out in cooperation with a major wind
turbine manufacturer, depending on the content.
In order for wind power to compete without
subsidies against other cheaper energy sources such as coal, a higher
reliability is needed for lowering downtime and maintenance expenses. Bearings
are one of the critical components for the wind turbine drivetrain, being present
at the main shaft, gearbox and generator. Although bearings are designed for a
20 year life span, failure after 1 or 2 years from WEC is not uncommon.
Maintenance and repair of bearing related failures are very costly and some
turbine manufacturers consider WEC to be the most expensive technical issue for
This project focuses on comparing several types
of bearing materials acquired from different bearing manufacturers, as well as new
experimental alloys. The bearings will be tested using accelerated WEC bearing
tests rigs to find the best suitable material and failure analysis will be
performed for investigating the damage mechanism for each material. Light
optical microscopy will be used for identifying crack networks and Scanning
Electron Microscopy (SEM) will be used for high resolution characterization of
WEC and chemical analysis of inclusions. The project could be expanded to
include state-of-the-art high resolution 3D X-ray CT scanning for mapping crack
networks in three dimensions.
The project should help clarify how to avoid
White Etch Cracks formation in bearings, which has arguably been the all-time single
most expensive failure mode out of all wind turbine components. More
specific goals should be defined between the project student and the
supervisor, depending on which areas of research the student finds interesting.
Some background in materials or mechanical engineering.