An Evaluation Of Bearings Operating In A Cryogenic Environment With Silicon Nitride Rolling Elements PDF Download
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Author | : |
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Total Pages | : 28 |
Release | : 1991 |
Genre | : |
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Download An Evaluation of Bearings Operating in a Cryogenic Environment with Silicon Nitride Rolling Elements Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 704 |
Release | : 1995 |
Genre | : Aeronautics |
ISBN | : |
Download Scientific and Technical Aerospace Reports Book in PDF, ePub and Kindle
Author | : Balamurugan Karunamurthy |
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Total Pages | : |
Release | : 2009 |
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Download Erosion and Rolling Contact Wear Mechanisms in Silicon Nitride Hybrid Bearings Book in PDF, ePub and Kindle
One remarkable advantage of hybrid bearings over all steel bearings is the elimination of separate oil lubricant system in applications, such as compressors and pumps in refrigeration and air conditioning units. High speed test runs restricted increase in speed due to material wear, which eventually affected the life of bearings. Being low saturation temperature fluids, change of phase is very common in refrigerants and cryogenic liquids, which lead to cavitation. Silicon nitride rolling elements with different sintering additives, properties and microstructure were experimentally studied to understand the nature of cavitation erosion. Advanced surface analysis technique was used study the erosive wear correlation to microstructure of test materials. Cavitation erosion wear initiated by multiple intergranular and transgranular fracture, leading to erosion pit formation. Grain size and grain boundary composition have shown to be the dominant factors for providing resistance to cavitation. Effect of surface defects and lubricant viscosity on cavitation erosion was investigated and is detailed in this thesis. A rotary specimen method was designed to study the effect of cavitation on rolling bodies. Computational modelling of acoustically generated cavitation was attempted and is also reported in this work. A novel test methodology was designed and manufactured by modifying a rotary tribometer to allow controlled experimental testing of two different phenomena rolling contact fatigue and cavitation erosion. This testing made it possible to study rolling and erosive wear mechanisms of rolling elements. Cavitation created far away in this new system is shown to be transported to the rolling contacts. The mechanism of material damage was by surface weakening due to mechanical impact of bubbles, which enhance fluid entrance and hydrodynamic pressure leading to wear initiation. Micro erosion pits formed in the rolling contact, which accelerated the damage by dislodging grains and bunch of grains. This testing method is suitable for a qualitative assessment of cavitation-RCF damage for different fluids with varying viscosities, and operating conditions.
Author | : Timothy Raymond Jett |
Publisher | : |
Total Pages | : 92 |
Release | : 1991 |
Genre | : Bearings (Machinery) |
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Download Evaluation of Bearing Configurations Using the Single Bearing Tester in Liquid Nitrogen Book in PDF, ePub and Kindle
Author | : Erwin V. Zaretsky |
Publisher | : BiblioGov |
Total Pages | : 34 |
Release | : 2013-06 |
Genre | : |
ISBN | : 9781289146399 |
Download Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life Book in PDF, ePub and Kindle
Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than an all-steel rolling-element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-contact, and cylindrical roller hybrid bearings with races made of post-1960 bearing steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel bearing under the same load will have a longer life than the equivalent hybrid bearing under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than all-steel bearings by 58 percent for deep-groove bearings, 41 percent for angular-contact bearings, and 28 percent for cylindrical roller bearings.
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 32 |
Release | : 2018-05-30 |
Genre | : |
ISBN | : 9781720482772 |
Download Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life Book in PDF, ePub and Kindle
Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than an all-steel rolling-element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-contact, and cylindrical roller hybrid bearings with races made of post-1960 bearing steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel bearing under the same load will have a longer life than the equivalent hybrid bearing under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than all-steel bearings by 58 percent for deep-groove bearings, 41 percent for angular-contact bearings, and 28 percent for cylindrical roller bearings.Zaretsky, Erwin V. and Vlcek, Brian L. and Hendricks, Robert C.Glenn Research CenterFATIGUE LIFE; ROLLER BEARINGS; ROLLERS; SILICON NITRIDES; SERVICE LIFE; PREDICTIONS; STRESSES
Author | : K. E. Erhardt |
Publisher | : |
Total Pages | : 62 |
Release | : 1971 |
Genre | : Breeder reactors |
ISBN | : |
Download A Literature Review and Materials Evaluation for Rolling Bearings Operating in Liquid Sodium in the Temperature Range 800©F to 1200©F Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 22 |
Release | : 1986 |
Genre | : |
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Download Evaluation of a Hybrid Hydrostatic Bearing for Cryogenic Turbopump Application Book in PDF, ePub and Kindle
Author | : United States. National Aeronautics and Space Administration |
Publisher | : |
Total Pages | : 788 |
Release | : 1970 |
Genre | : NASA tech briefs |
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Download Cumulative Index to NASA Tech Briefs Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 792 |
Release | : 1970 |
Genre | : Aeronautics |
ISBN | : |
Download NASA Tech Brief Book in PDF, ePub and Kindle