Microslips between contacting paraboloids.
Hertz and Mindlin problems for fourth order paraboloids in contact generalized, minimizing microslips and annulus of slip
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Results for “ROLLING CONTACT”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Computer program analyzes whirl critical speeds and bearing loads for shafts coupled by nonlinear springs to machine housing
Computerized method of analysis predicts bearing loads, shaft deflections, and critical speeds for shafts coupled by rolling contact bearings to the machine housing. The bearing nonlinearities, casing as well as rotor dynamics, and rotor-imbalance forcing functions are all included in the system dynamics analysis.
Severud, L. K.↗
Design and testing of liquid hydrogen-cooled, ultrahigh-speed ball bearings
Large-bore, liquid hydrogen-cooled, ultrahigh-speed, rolling contact bearings of an optimum design allow optimization of large rocket engine turbopumps in which bearing speed is a limiting factor. Optimum design for the bearings resulted from an application of liquid hydrogen used as a coolant.
Butner, M. F.↗
Development of long life jet engine thrust bearings
Analyses, design, and testing of hybrid boost bearing based on fluid film and rolling contact elements
Badgley, R. H.↗
Isothermal elastohydrodynamic theory for the full range of pressure-viscosity coefficient
Isothermal elastohydrodynamic theory for full range of pressure-viscosity coefficient for heavily loaded rolling contacts
Cheng, H. S.↗
Fatigue life of high-speed ball bearings with silicon nitride balls
Evaluation of hot-pressed silicon nitride as a rolling-element bearing material. Two grades of hot-pressed silicon nitride balls were tested under rolling contact conditions in a five-ball fatigue tester. A digital computer program was used to predict the dynamic performance characteristics and fatigue life of high-speed ball bearings with silicon nitride balls relative to that with bearings containing steel balls. The results obtained include the finding that fatigue spalls on silicon nitride balls are similar in appearance to those obtained with typical bearing steels.
Parker, R. J.↗
Transient effect of lubricant on elastohydro-dynamic film thickness
The inlet solution of the elastohydrodynamic lubricated rolling contact problem was obtained by considering lubricants with transient viscosity. The effect of the viscoelastic retardation time of the lubricant on the center film thickness was investigated. The effect of transient viscosity in response to a sudden pressure was found to be insignificant in determining the film thickness in elastohydrodynamic contacts.
Wang, K. L.↗
Flexural fatigue of hollow rolling elements
Hollow cylindrical bars were tested in the rolling-contact fatigue tester to determine the effects of material and outside diameter to inside diameter (OD/ID) ratios of 2.0, 1.6, 1.4, and 1.2 on fatigue failure mode and subsequent failure propagation. The range of applied loads with these OD/ID ratios resulted in maximum tangential tensile stresses ranging from 165 to 655 megapascals (24,000 to 95,000 psi) at the bore surface. Flexural failures of the hollow test bars occurred when this bore stress was 490 megapascals (71,000 psi) or greater with AISI 52100 hollow bars and 338 megapascals (49,000 psi) or greater with AISI M-50 hollow bars. Good correlation was obtained in relating the failures of these hollow bars with flexural failures of drilled balls from previously published full scale bearing tests.
Bamberger, E. N.↗
Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests
The types and quantities of wear particles generated during accelerated ball rolling contact fatigue tests were determined. Ball specimens were made of AMS 5749, a corrosion resistant, high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.215 times 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed; normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.
Jones, W. R., Jr.↗
Effect of wall thickness and material on flexural fatigue of hollow rolling elements
Hollow cylindrical bars were tested in a rolling-contact fatigue tester to determine the effects of material and outside diameter to inside diameter (OD/ID) ratios on fatigue failure mode and subsequent failure propagation. The range of applied loads with OD/ID ratios of 2.0, 1.6, 1.4, and 1.2 resulted in maximum tangential tensile stresses ranging from 165 to 655 MPa at the bore surface. Flexural failures of the hollow test bars occurred when this bore stress was 490 MPa or greater with AISI 52100 hollow bars and 338 MPa or greater with AISI M-50 hollow bars. Good correlation was obtained in relating the failures of these hollow bars with flexural failures of drilled balls from full-scale bearing test published previously.
Bamberger, E. N.↗
Helical grip for the cable cars of San Francisco
A helical cable car grip to minimize high maintenance costs of San Francisco's cable car operation is presented. The grip establishes a rolling contact between the cable and grip to reduce sliding friction and associated cable wear. The design, development, and testing of the helical cable car grip are described.
Peyran, R. J.↗
Status of Understanding for Bearing Materials
The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.
E N Bamberger↗
Ion Implantatiion Improves Bearing-Surface Properties
Selected ions fired into rolling elements to increase resistance to rolling-contact fatique. Mask strips confine implantation to 105 degree arcs on cylindrical surfaces. Specimens kept cool by copper block through which refrigerant is circulated. Implanting nitrogen or titanium ions in metals improves resistance to fatigue, corrosion, and wear without altering bulk properties. Unlike such surface treatments as conventional nitriding, conventional carburizing, and coating, ion implantation is low-temperature process, requires no finishing operations, and produces highly-alloyed surface layer. Implantation process also helps conserve such strategic materials as chromium and cobalt by using them only where needed.
Misra, M. S.↗
Powder metallurgy bearings for advanced rocket engines
Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.
Fleck, J. N.↗
A rotating electrical transfer device
The design, development, and performance characteristics of two roll ring configurations - a roll ring being a device used in transferring electrical energy across a continuously rotating or oscillating interface through one or more flexible rolling contacts, or flexures are described. Emphasis is placed on the design problems and solutions encountered during development in the areas of flexure fatigue, contact electroplating, electrical noise, and control of interface geometry. Also, the present status of each configuration is summarized.
Porter, R. S.↗
Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials
Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.
Townsend, D. P.↗
Advanced bearing materials for cryogenic aerospace engine turbopump requirements
The properties of eleven alloys were investigated to select an improved bearing material for the High Pressure Oxygen Turbo Pump which delivers liquid oxygen to the Space Shuttle Main Engine. The alloys, selected through detailed literature analysis, X 405, MRC-2001, T440V, 14-4/6V, D-5, V-M Pyromet 350, Stellite 3, FerroTic CS-40, Tribaloy 800, WD-65, and CBS-600. The alloys were tested in hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness tests, and their performance was compared with the baseline 440C test alloy. As a result, five alloys were eliminated, leaving the remaining six (X 405, MRC-2001, T440V, 14-4/6V, D-5, and WD-65 to be evaluated in the next phase of NASA tests which will include fracture toughness, rolling contact fatigue, wear resistance, and corrosion resistance. From these, three alloys will be selected, which will be made into ninety bearings for subsequent testing.
Friedman, G.↗
Predicting Temperatures In Ball Bearings
Computer simulations speed design studies. Analyses performed in two or three dimensions. Sizes and shapes of components approximated by zones or nodes connected by gridlines. From geometric information about grids and boundary conditions, properties of bearing and lubricant materials, and information supplied by users, thermal-analysis programs generate mathematical models for thermal transport. Thermal analysis of high-speed rolling contact bearings matured so much that computerized numerical simulations replace expensive time consuming full scale experiments.
Wagner, William R.↗