Download or read book An Evaluation of Bearings Operating in a Cryogenic Environment with Silicon Nitride Rolling Elements written by and published by . This book was released on 1991 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Bearing Configurations Using the Single Bearing Tester in Liquid Nitrogen written by Timothy Raymond Jett and published by . This book was released on 1991 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Erosion and Rolling Contact Wear Mechanisms in Silicon Nitride Hybrid Bearings written by Balamurugan Karunamurthy and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life written by Erwin V. Zaretsky and published by BiblioGov. This book was released on 2013-06 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-30 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book A Literature Review and Materials Evaluation for Rolling Bearings Operating in Liquid Sodium in the Temperature Range 800 F to 1200 F written by K. E. Erhardt and published by . This book was released on 1971 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of a Hybrid Hydrostatic Bearing for Cryogenic Turbopump Application written by and published by . This book was released on 1986 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cumulative Index to NASA Tech Briefs written by United States. National Aeronautics and Space Administration and published by . This book was released on 1970 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1991 with total page 1332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Tech Brief written by and published by . This book was released on 1970 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Annual Report 1989 90 written by New Brunswick. Department of Transportation and published by . This book was released on 1991 with total page 1272 pages. Available in PDF, EPUB and Kindle. Book excerpt: General activity review of associated branches and agencies to the Department which includes corporate securities registrations, a list of tenders received, and general financial data. Branches and agencies reviewed are responsible for motor vehicle activity, highway construction, traffic engineering, telecommunications and public utilities.

Download or read book Effect of Surface and Mechanical Properties on Silicon Nitride Bearing Element Performance written by and published by . This book was released on 1975 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report discusses the importance of understanding the extent of surface damage caused during the manufacture of bearing surfaces on ceramics. The likely impact of the damaged surface on the usefulness of ceramics as rolling bearing materials is presented. The results of flat-washer rolling- contact fatigue tests signify the role of surface interactions in a steel- silicon nitride contact on the life of the contact. The variables evaluated include lubricant viscosity, surface finish of the silicon nitride washer, type of contact (line or point) and hardness of the steel rollers. The effect of the lower density and higher elastic modulus of silicon nitride on bearing fatigue life was analytically evaluated. The analysis shows that silicon nitride rolling elements can improve the fatigue life of very high speed bearings.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991-07 with total page 1444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book FY 1991 Scientific and Technical Reports Articles Papers and Presentations written by and published by . This book was released on 1991 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Reference Publication written by and published by . This book was released on 1977 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineered Materials Abstracts written by and published by . This book was released on 1994-07 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: