AmpsAstray: Stray Current in Wind Turbines
Context
Wind turbines are complex structures that require optimized design and maintenance to ensure long-term operability, especially in offshore conditions. Aiming for more compact and cost-effective configurations, there is a trend towards a higher level of integration between the gearbox and the generator. This requires robust measures to prevent stray currents from causing damage to mechanical components such as bearings. Stray currents may, among others, impact lubricant degradation resulting in an increased presence of hydrogen, which may ingress in the materials and potentially increase White Etching Cracks (WEC). Therefore, to ensure wind reliability, this project aims to evaluate the interplay of stray current, hydrogen embrittlement, and WEC formation, by quantifying the role of hydrogen in the degradation of bearing steels due to stray currents.
Research objectives
The main objective of this project is to quantify the contribution of hydrogen in the degradation of bearing steels and validate testing methods for evaluation of White Etching Crack (WEC) resistance under Hydrogen Embrittlement (HE) conditions. This is intended to be achieved through:
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Microstructural characterization to establish a link between bearing steel microstructure and its susceptibility to HE. Techniques such Scanning Electron Microscopy (SEM), Electron Back-Scatter Diffraction (EBSD) and X-Ray Diffraction (XRD) will be applied.
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Hydrogen-specific characterization to understand the material-hydrogen interactions. For this, the materials will be electrochemically charged and tested via hot/melt extraction, thermal desorption spectroscopy (TDS) and permeation using a Devanathan-Stachurski cell to study the apparent hydrogen diffusion coefficient.
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Mechanical testing to determine the Hydrogen Embrittlement Threshold Stress (σth-EHE) via the Incremental Step Load Test (ASTM F1624). Notched specimens with a square cross-section will be tested in four-point bending mode. For this, a test cell will be developed.
Project logo and funding logo
This project is supported by VLAIO, the Flanders Innovation & Entrepreneurship Agency and ZF Wind Power (ZFWP).
Researchers