White Etching Cracking—Simulation in Bearing Rig and Bench Tests

Franke, Joerg; Carey, Jim T.; Korres, Spyros; Haque, T.; Jacobs, Peter W.; Loos, Jörg; Kruhoeffer, Wolfram

doi:10.1080/10402004.2017.1339839

Cited by 30 publications

(24 citation statements)

References 15 publications

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“…The oil compounds selected for this investigation were used in bearing lubricants in several test benches by project partners to instigate WEC failure. Bearings in wind turbine gearboxes as well as other industrial applications suffer from costly, unplanned maintenance due to WECs [6][7][8][9][10][11]. In addition, oil additives have been shown to influence risk of WECs [22,24,25].…”

Section: Data Descriptionmentioning

confidence: 99%

“…Such failures are responsible for significant operating and downtime costs, especially for wind turbine gearboxes [3][4][5]. To put the importance of WEC failures into perspective, WECs can lead to bearing failures within 5%-20% of the bearing's L10 lifespan (DIN ISO 281), leading to unexpected maintenance costs [6][7][8][9][10][11]. Several recent investigations aimed at understanding the causes behind WEC related bearing failure in wind turbine gearboxes [5,[11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Several recent investigations aimed at understanding the causes behind WEC related bearing failure in wind turbine gearboxes [5,[11][12][13][14][15][16][17][18][19][20]. However, the causes of WEC bearing failures remain a subject of debate [5,10,[21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…These results not only implicate the so-called 'WEC critical oil', but also indicate that oil additives may have an influence on risk of WECs. Similarly, several other investigations used a specific oil, containing additives, to successfully promote WEC failure [1,10,21,23,27], the most recent of which is the investigation by Gould et al, where lubricant additives were systematically varied to study the effect of different additive combinations on bearing time until failure [24]. The investigation found that the lubricant containing zinc dialkyl-dithiophosphate (ZnDDP) led to WECs sooner than any other tested lubricant under the test conditions [24].…”

Section: Introductionmentioning

confidence: 99%

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Pattern Discovery in White Etching Crack Experimental Data Using Machine Learning Techniques

et al. 2019

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White etching crack (WEC) failure is a failure mode that affects bearings in many applications, including wind turbine gearboxes, where it results in high, unplanned maintenance costs. WEC failure is unpredictable as of now, and its root causes are not yet fully understood. While WECs were produced under controlled conditions in several investigations in the past, converging the findings from the different combinations of factors that led to WECs in different experiments remains a challenge. This challenge is tackled in this paper using machine learning (ML) models that are capable of capturing patterns in high-dimensional data belonging to several experiments in order to identify influential variables to the risk of WECs. Three different ML models were designed and applied to a dataset containing roughly 700 high- and low-risk oil compositions to identify the constituting chemical compounds that make a given oil composition high-risk with respect to WECs. This includes the first application of a purpose-built neural network-based feature selection method. Out of 21 compounds, eight were identified as influential by models based on random forest and artificial neural networks. Association rules were also mined from the data to investigate the relationship between compound combinations and WEC risk, leading to results supporting those of previous analyses. In addition, the identified compound with the highest influence was proved in a separate investigation involving physical tests to be of high WEC risk. The presented methods can be applied to other experimental data where a high number of measured variables potentially influence a certain outcome and where there is a need to identify variables with the highest influence.

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Section: Data Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pattern Discovery in White Etching Crack Experimental Data Using Machine Learning Techniques

et al. 2019

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“…Several researchers have indicated that lubricant-induced hydrogen is the root cause of WEC (Evans (1); Iso, et al (10); Newlands, et al (11); Franke, et al (23)). Newlands, et al (11) found that gaseous hydrogen can be evolved from oils and greases at lubricated contacts.…”

Section: Introductionmentioning

confidence: 99%

Lubricant Effects on White Etching Cracking Failures in Thrust Bearing Rig Tests

Haque

Korres

Carey

et al. 2018

Tribology Transactions

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White etching cracking (WEC) is a subsurface bearing failure mechanism influenced by a number of factors, including lubricant composition. Certain metal-containing lubricants have been reported to promote WEC-induced failure; however, the exact mechanisms linking lubricant effects on WEC propensity are still not fully understood. An interesting field that has not been elucidated is the influence of additive concentration and tribofilm growth on WEC initiation, propagation, and failure. The investigations conducted in this work involved two series of oil formulations: one with additives that give rise to WEC (WEC oils) in different combinations and concentrations and another with additives that do not cause WEC (non-WEC oils). A mini traction machine (MTM) in combination with a spacer layer imaging machine (SLIM) was employed to study the growth of tribofilms and their influence on friction response. Insights from the MTM-SLIM study allowed for better interpretation of FE8 bearing tests. When using oils that contribute to WEC formation, the tribofilm-induced WEC mechanism was confirmed, with cracks initiating as early as after 20 h of FE8 testing. Metal-containing additives were found to favor the formation of WECs by generating a high-friction tribofilm and increasing the water content in the lubricant. Furthermore, the source of subsurface H associated with WEC failure is investigated using heavy water (D2O)-saturated oil. A mechanism of water dissociation induced in tribofilm growth (incubation period) is proposed in this article.

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