White Etching Cracks in wind turbine bearings

Abstract

Wind turbine (WT) gear boxes are prone to failure well below the expected 20 years’ lifetime of a WT. It has been identified that most of the failures observed are due to white etch crack flaking. Although this type of failure has been intensely studied, the underlying mechanisms have not been identified; however, recent advances have shown that non-metallic inclusions might act as crack initiators. In this work, different bearings presenting this type of damage will be examined via microtomography scans and high precision serial sectioning to reveal surfaces displaying crack-inclusion interactions. Furthermore, by means of energy dispersive X-ray spectrometry it will be possible to investigate the chemical composition of the non-metallic inclusions. The findings will be compared to current initiation and propagation theories proposed in literature; Thus, this study will add experimental observations to current investigations using a novel technique.