Micro-Sliding in High-Speed Aircraft Engine Ball Bearings

Gloeckner, Peter; Ebert, Franz-Josef

doi:10.1080/10402000903312364

Cited by 30 publications

(22 citation statements)

References 5 publications

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“…59 Butterflies are known to form at high contact stresses even in the M50/M50NiL alloys, 21 but have not been reported in any study from bearings that have experienced service. 60 Indeed, rolling contact fatigue is not a key feature in the failure of aeroengine bearings: the vast majority of operational failures in M50/M50NiL bearings are due to surface distress; [61][62][63] although such distress can initiate cracks that grow by a fatigue mechanism, leading eventually to spalling, the important Bhadeshia and Solano-Alvarez Elimination of white etching matter in bearing steels Materials Science and Technology 2015 VOL 31 NO 9 distinction is that initiation does not begin below the surface where rolling contact stresses are maximal. A longer term solution is to make tougher bearing steels that have a ductile failure mechanism in the stress affected region.…”

Section: Hypothesis and Solutionsmentioning

confidence: 99%

Critical Assessment 13: Elimination of white etching matter in bearing steels

Bhadeshia

Solano-Alvarez

2015

Materials Science and Technology

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One form of damage due to rolling contact fatigue is the formation of localised regions of extremely hard material forming within the body of a bearing. These regions have a relatively homogeneous structure and hence etch mildly with respect to the surrounding unaffected matrix. They, therefore, appear white in a darker background when examined using optical microscopy. We assess here the cause of this damage and propose solutions that are backed by evidence that already is available. The issue is important because of the spate of unexpected failures in large wind turbine bearings and of generic importance in determining the life of more well behaved bearing applications.

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Section: Hypothesis and Solutionsmentioning

confidence: 99%

Critical Assessment 13: Elimination of white etching matter in bearing steels

Bhadeshia

Solano-Alvarez

2015

Materials Science and Technology

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“…The thermal EHL theory is therefore a suitable method in order to predict rolling contact friction and power loss, to understand experimental investigation results, and to investigate high speed bearing phenomena, such as the phenomenon of micro-sliding, occurring in high speed ball bearings. Micro-sliding-as a result of the changing effective radii following a certain raceway curvature within the major axis of the contact ellipse-leads to additional contact friction heat as described by [15]. This means in respect to rolling contact calculation, thermal effects have to be considered (Gloeckner et al [16]).…”

Section: High Speed Bearing Analysismentioning

confidence: 99%

The Evolution of Reliability and Efficiency of Aerospace Bearing Systems

Gloeckner¹,

Rodway²

2017

ENG

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The worldwide air traffic underwent a rapid development in recent decades. Between the early 70s and the late 90s of the last century civil air traffic doubled every 15 years. The civil aviation market will continue to grow with 4% -5% each year within the next 20 years. This enormous growth represents major challenges for airframers, engine makers, suppliers, airlines, air traffic management and ground infrastructure. In addition, the public debate on the worldwide civil air traffic is dominated by environmental and climate issues, even though only 2% of the man-made carbon dioxide (CO 2 ) emissions are due to air transportation. Therefore the aerospace industry will have to focus on a low-emission and quite air traffic, and on the conservation of natural resources and our environment. The end-use consumer and environmental policy requirements for aircrafts of the next generation translate into components with improved efficiency and reliability. Rolling bearings are one of these components which significantly determine the reliability and mechanical efficiency of aerospace applications such as aircraft and rotorcraft engines and transmission systems. They have to withstand very demanding operating conditions. Especially main shaft bearings in modern aircraft engines experience high rotational speeds and temperatures. Furthermore aerospace bearings have to meet the highest reliability standards and require low-weight design solutions. These operating conditions and requirements present a continuous challenge for improvements in all fields of bearing technology. This article presents solutions in aspects of materials, design, analysis, and surface technologies in order to meet the environmental, reliability, and economical requirements of advanced aerospace bearing systems. State of the art bearing analysis and advanced bearing design solutions contributing to lower friction power losses and increased systems efficiency are discussed. Weight, functional, and maintenance benefits are presented with the example of highly integrated aircraft engine main shaft bearings. It is also shown that the progress in bearing materials and surface technology devel-

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“…However, the most commonly reported failures are due to surface-initiated damage rather than due to subsurface stresses induced during rolling-contact. [1][2][3] The duplex hardening process which is the subject of this review deals precisely with the enhancement of surface properties and hence is particularly relevant to aeroengine bearings.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6][7] Secondary hardening 2 of the component is necessary, since it is essential to attain the proper hardness before the start of the nitrding process. The goal is to achieve a superior tribological resistance through an increased surface hardness, and possibly by the raising the level of compressive residual stress in the region near the surface.…”

Section: Introductionmentioning

confidence: 99%

Duplex Hardening of Steels for Aeroengine Bearings

Ooi

Bhadeshia

2012

ISIJ Int.

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Duplex hardening is a process in which conventional heat-treatments such as secondary or case hardening are followed up by surface nitriding to achieve exceptional properties, particularly in the context of aeroengine bearings. Hardness values in excess of 1 000 HV can in principle be achieved, and although the hardness decreases as a function of depth below the surface, some level of enhancement can occur to a depth of up to 0.2 mm. The process can be applied to both through hardened and case hardened bearing steels such as M50 and M50NiL respectively, with concomitant increases in rolling contact fatigue resistance and tribological properties. The process has not yet been universally adopted and is ripe for a critical assessment.

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Micro-Sliding in High-Speed Aircraft Engine Ball Bearings

Cited by 30 publications

References 5 publications

Critical Assessment 13: Elimination of white etching matter in bearing steels

Critical Assessment 13: Elimination of white etching matter in bearing steels

The Evolution of Reliability and Efficiency of Aerospace Bearing Systems

Duplex Hardening of Steels for Aeroengine Bearings

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