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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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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

NASA gear research and its probable effect on rotorcraft transmission design

The NASA Lewis Research Center devised a comprehensive gear technology research program beginning in 1969, the results of which are being integrated into the NASA civilian Helicopter Transmission System Technology Program. Attention is given to the results of this gear research and those programs which are presently being undertaken. In addition, research programs studying pitting fatigue, gear steels and processing, life prediction methods, gear design and dynamics, elastohydrodynamic lubrication, lubrication methods and gear noise are presented. Finally, the impact of advanced gear research technology on rotorcraft transmission design is discussed.

Zaretsky, E. V.↗
NASA NTRS2019

Oil-Free Enabling Technology: Gas Foil Bearings

NASA has developed and commercialized high temperature coatings and bearings for extreme conditions. These technologies are now under consideration by industry for automotive applications such as turbochargers, fuel cell compressors and exhaust gas path mechanism applications. In this presentation, a review of Oil-Free technologies and their current state-of-development is introduced. Key NASA contributions to the field as documented by patents, research papers and technology demonstrations is also presented.

lubrication↗
NASA NTRS2015

On the Correlation of Specific Film Thickness and Gear Pitting Life

The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive dataset. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures. This study includes previously reported data, results of an additional 50 tests, and detailed information from lab notes and tested gears. The dataset comprised 258 tests covering specific film values (0.47 to 5.2). The experimentally determined surface fatigue lives, quantified as 10-percent life estimates, ranged from 8.7 to 86.8 million cycles. The trend is one of increasing life for increasing specific film. The trend is nonlinear. The observed trends were found to be in good agreement with data and recommended practice for gears and bearings. The results obtained will perhaps allow for the specific film parameter to be used with more confidence and precision to assess gear surface fatigue for purpose of design, rating, and technology development.

gears↗
NASA NTRS1992

Lubrication of space systems: Challenges and potential solutions

Future space missions will all require advanced mechanical moving components which will require wear protection and lubrication. The tribology practices used today are primarily based upon a technology base that is more than 20 years old. This paper will discuss NASA's future space missions and some of the mechanism tribology challenges that will be encountered. Potential solutions to these challenges using coatings technology will be assessed.

Fusaro, Robert L.↗
NASA NTRS1993

Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 4 - Tribological materials and NDE

The present volume on tribological materials and NDE discusses liquid lubricants for advanced aircraft engines, a liquid lubricant for space applications, solid lubricants for aeronautics, and thin solid-lubricant films in space. Attention is given to the science and technology of NDE, tools for an NDE engineering base, experimental techniques in ultrasonics for NDE and material characterization, and laser ultrasonics. Topics addressed include thermal methods of NDE and quality control, digital radiography in the aerospace industry, materials characterization by ultrasonic methods, and NDE of ceramics and ceramic composites. Also discussed are smart materials and structures, intelligent processing of materials, implementation of NDE technology on flight structures, and solid-state weld evaluation.

Fusaro, Robert L.↗
NASA NTRS2004

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

Dempsey, Paula J.↗
NASA NTRS2003

NASA PS304 Lubricant Tested in World's First Commercial Oil-Free Gas Turbine

In a marriage of research and commercial technology, a 30-kW Oil-Free Capstone microturbine electrical generator unit has been installed and is serving as a test bed for long-term life-cycle testing of NASA-developed PS304 shaft coatings. The coatings are used to reduce friction and wear of the turbine engine s foil air bearings during startup and shut down when sliding occurs, prior to the formation of a lubricating air film. This testing supports NASA Glenn Research Center s effort to develop Oil-Free gas turbine aircraft propulsion systems, which will employ advanced foil air bearings and NASA s PS304 high temperature solid lubricant to replace the ball bearings and lubricating oil found in conventional engines. Glenn s Oil-Free Turbomachinery team s current project is the demonstration of an Oil-Free business jet engine. In anticipation of future flight certification of Oil-Free aircraft engines, long-term endurance and durability tests are being conducted in a relevant gas turbine environment using the Capstone microturbine engine. By operating the engine now, valuable performance data for PS304 shaft coatings and for industry s foil air bearings are being accumulated.

Weaver, Harold F.↗
NASA NTRS2007

Design of Oil-Lubricated Machine for Life and Reliability

In the post-World War II era, the major technology drivers for improving the life, reliability, and performance of rolling-element bearings and gears have been the jet engine and the helicopter. By the late 1950s, most of the materials used for bearings and gears in the aerospace industry had been introduced into use. By the early 1960s, the life of most steels was increased over that experienced in the early 1940s, primarily by the introduction of vacuum degassing and vacuum melting processes in the late 1950s. The development of elastohydrodynamic (EHD) theory showed that most rolling bearings and gears have a thin film separating the contacting bodies during motion and it is that film which affects their lives. Computer programs modeling bearing and gear dynamics that incorporate probabilistic life prediction methods and EHD theory enable optimization of rotating machinery based on life and reliability. With improved manufacturing and processing, the potential improvement in bearing and gear life can be as much as 80 times that attainable in the early 1950s. The work presented summarizes the use of laboratory fatigue data for bearings and gears coupled with probabilistic life prediction and EHD theories to predict the life and reliability of a commercial turboprop gearbox. The resulting predictions are compared with field data.

Zaretsky, Erwin V.↗
NASA NTRS2007

Characterization of Lubricants on Ball Bearings by FT-IR Using an Integrating Sphere

Fourier Transform-Infrared reflectance microspectroscopy has been used extensively for the examination of coatings on nonplanar surfaces such as ball bearings. While this technique offers considerable advantages, practical application has many drawbacks, some of which are easily overcome by the use of integrating sphere technology. This paper describes the use of an integrating sphere for the quantification of thin layers of lubricant on the surface of ball bearings and the parameters which require optimization in order to obtain reliable data. Several applications of the technique are discussed including determination of lubricant load on 12.7 mm steel ball bearings and the examination of degraded lubricant on post mortem specimens.

Street, K. W.↗
NASA NTRS2013

Folding Elastic Thermal Surface - FETS

The FETS is a light and compact thermal surface (sun shade, IR thermal shield, cover, and/or deployable radiator) that is mounted on a set of offset tape-spring hinges. The thermal surface is constrained during launch and activated in space by a thermomechanical latch such as a wax actuator. An application-specific embodiment of this technology developed for the MATMOS (Mars Atmospheric Trace Molecule Occultation Spectrometer) project serves as a deployable cover and thermal shield for its passive cooler. The FETS fits compactly against the instrument within the constrained launch envelope, and then unfolds into a larger area once in space. In this application, the FETS protects the passive cooler from thermal damage and contamination during ground operations, launch, and during orbit insertion. Once unfolded or deployed, the FETS serves as a heat shield, intercepting parasitic heat loads by blocking the passive cooler s view of the warm spacecraft. The technology significantly enhances the capabilities of instruments requiring either active or passive cooling of optical detectors. This can be particularly important for instruments where performance is limited by the available radiator area. Examples would be IR optical instruments on CubeSATs or those launched as hosted payloads because radiator area is limited and views are often undesirable. As a deployable radiator, the panels making up the FETS are linked thermally by thermal straps and heat pipes; the structural support and deployment energy is provided using tape-spring hinges. The FETS is a novel combination of existing technologies. Prior art for deployable heat shields uses rotating hinges that typically must be lubricated to avoid cold welding or static friction. By using tape-spring hinges, the FETS avoids the need for lubricants by avoiding friction altogether. This also eliminates the potential for contamination of nearby cooled optics by outgassing lubricants. Furthermore, the tape-spring design of the FETS is also self-locking so the panels stay in a rigid and extended configuration after deployment. This unexpected benefit makes the tape-spring hinge design of the FETS a light, simple, reliable, compact, non-outgassing hinge, spring, and latch. While tape-spring hinges are not novel, they have never been used to deploy passive unfolding thermal surfaces (radiator panels, covers, sun shades, or IR thermal shields). Furthermore, because this technology is compact, it has minimal impact on the launch envelope and mass specifications. FETS enhances the performance of hosted payload instruments where the science data is limited by dark noise. Incorporating FETS into a thermal control system increases radiator area, which lowers the optical detector temperature. This results in higher SNR (signal-to-noise ratio) and improved science data.

Urquiza, Eugenio↗
NASA NTRS1986

Rolling element bearings in space

Some of the advances in tribology that have been associated with aerospace mechanisms are discussed. The needs of aerospace have been the dominant forces leading to improvements in understanding and applying tribology technology. In the past two decades improvements in understanding bearing torque, elastohydrodynamic lubrication, lubricant distribution, cage stability, and transfer film lubricants have been made. It is anticipated that further developments will be made in response to future aerospace requirements.

Kannel, J. W.↗
NASA NTRS1990

The 24th Aerospace Mechanisms Symposium

The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures.

Source record↗
NASA NTRS1994

The 28th Aerospace Mechanisms Symposium

The proceedings of the 28th Aerospace Mechanisms Symposium, which was hosted by the NASA Lewis Research Center and held at the Cleveland Marriott Society Center on May 18, 19, and 20, 1994, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft.

Rohn, Douglas A.↗
NASA NTRS1995

The 29th Aerospace Mechanisms Symposium

The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft.

Schneider, William C.↗
NASA NTRS2006

Current Research Activities in Drive System Technology in Support of the NASA Rotorcraft Program

Drive system technology is a key area for improving rotorcraft performance, noise/vibration reduction, and reducing operational and manufacturing costs. An overview of current research areas that support the NASA Rotorcraft Program will be provided. Work in drive system technology is mainly focused within three research areas: advanced components, thermal behavior/emergency lubrication system operation, and diagnostics/prognostics (also known as Health and Usage Monitoring Systems (HUMS)). Current research activities in each of these activities will be presented. Also, an overview of the conceptual drive system requirements and possible arrangements for the Heavy Lift Rotorcraft program will be reviewed.

Handschuh, Robert F.↗
NASA NTRS1984

The trend of future gas turbine technology

Future gas turbine technology will be based on contributions to the technology base being made today. At the NASA Lewis Research Center in Cleveland, OH, research is being conducted on turbomachinery system components and in a number of associated disciplines to advance the technology of aviation turbofan and torbojet engines. Areas of research include compressors, turbines, internal flow analysis, combustion, fuels, materials, structures, bearings, seals, lubrication, dynamics and controls, and instrumentation. A review of the research directions being taken in these areas and the steady advances being made provides a reasonable glimpse at gas turbine technology of the future.

Hartmann, M. J.↗
NASA NTRS2007

A Review of Tribomaterial Technology for Space Nuclear Power Systems

The National Aeronautics and Space Administration (NASA) has recently proposed a nuclear closed-cycle electric power conversion system for generation of 100-kW of electrical power for space exploration missions. A critical issue is the tribological performance of sliding components within the power conversion unit that will be exposed to neutron radiation. This paper presents a review of the main considerations that have been made in the selection of solid lubricants for similar applications in the past as well as a recommendations for continuing development of the technology.

Stanford, Malcolm K.↗
NASA NTRS1979

NASA gear research and its probable effect on rotorcraft transmission design

The results of the NASA gear research is reviewed as well as those programs which are presently being undertaken. Research programs studying pitting fatigue, gear steels and processing, life prediction methods, gear design and dynamics, elastohydrodynamic lubrication, lubrication methods and gear noise are presented. The impact of advanced gear research technology on rotorcraft transmission design is discussed.

Zaretsky, E. V.↗