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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Evaluation of ceramics for stator application: Gas turbine engine report

Current ceramic materials, component fabrication processes, and reliability prediction capability for ceramic stators in an automotive gas turbine engine environment are assessed. Simulated engine duty cycle testing of stators conducted at temperatures up to 1093 C is discussed. Materials evaluated are SiC and Si3N4 fabricated from two near-net-shape processes: slip casting and injection molding. Stators for durability cycle evaluation and test specimens for material property characterization, and reliability prediction model prepared to predict stator performance in the simulated engine environment are considered. The status and description of the work performed for the reliability prediction modeling, stator fabrication, material property characterization, and ceramic stator evaluation efforts are reported.

Trela, W.↗
NASA NTRSDate not supplied

Recent Advances in LIBS for Real-Time Detection of Silicone Contaminants on CFRP Surfaces

Laser induced breakdown spectroscopy (LIBS) is a materials characterization technique that has been advanced and refined to provide in situ, real-time quality control of carbon fiber reinforced polymer (CFRP) surfaces. As part of an effort to improve process control for adhesive bonding, a LIBS system was designed and assembled at NASA Langley Research Center (LaRC) to enable detection of ultralow concentrations of silicone contamination on CFRP adherends. The LIBS instrument provides high sensitivity detection and quasi-nondestructive surface characterization of CFRP adherends prior to adhesive bonding. This review focuses on the advancements at LaRC using LIBS as a quality control tool for the detection of silicone contaminants for improved adhesive bonding reliability of CFRP materials. This work describes how the LIBS technique was advanced by analyzing the laser parameters, studying the laser-matter interactions, and performing time-resolved measurements to determine the optimal plasma conditions for elemental detection. In addition, LIBS results were compared to X-ray photoelectron spectroscopy data to enable quantitative analysis from analytical calibration curves. Examples are shown of how to perform surface mapping of silicone contamination. Finally, a brief discussion is also presented on LIBS instrumentation, recommendations for laser parameters and instrumentation components, and LIBS technique maturity.

Surface characterization, Carbon fiber reinforced ↗
NASA NTRSDate not supplied

Recent Advances in LIBS for Real-Time Detection of Silicone Contaminants on CFRP Surfaces

Laser induced breakdown spectroscopy (LIBS) is a materials characterization technique that has been advanced and refined to provide in situ, real-time quality control of carbon fiber reinforced polymer (CFRP) surfaces. As part of an effort to improve process control for adhesive bonding, aLIBS system was designed and assembled at the NASA Langley Research Center (LaRC) to enable detection of ultra low concentrations of silicone contamination on CFRP adherends. The LIBS instrument provides high sensitivity detection and quasi-nondestructive surface characterization ofCFRP adherends prior to adhesive bonding. This review focuses on the advancements at LaRC using LIBS as a quality control tool for the detection of silicone contaminants for improved adhesive bonding reliability of CFRP materials. This work describes how the LIBS technique was advanced by analyzing the laser parameters, studying the laser-matter interactions, and performing time-resolved measurements to determine the optimal plasma conditions for elemental detection. In addition, LIBS results were compared to X-ray photoelectron spectroscopy data to enable quantitative analysis from analytical calibration curves. Examples are shown of how to perform surface mapping of silicone contamination. Finally, a brief discussion is presented on LIBS instrumentation, recommendations for laser parameters and instrumentation components, and LIBS technique maturity

Rodolfo I. Ledesma↗
NASA NTRS2004

Using AVIRIS Data to Map and Characterize Subaerially and Subaqueously Erupted BasalticVolcanic Tephras: The Challenge of Mapping Low-Albedo Materials

Increases in the signal-to-noise ratio (SNR) in AVIRIS has enabled the mapping and characterization of low albedo materials. Low albedo materials of interest include certain soils, man-made materials (asphalt, certain building materials, tires, etc.), and basaltic lava flows and ashes. Early in its history, the response of the AVIRIS sensor was not sensitive enough so that these low albedo materials could be reliably mapped. However, as indicated by Green and Pavri (2002) the noise equivalent delta radiance (NEdL) of AVIRIS in the 2001 flight season was below 0.010 in all but the shortest wavelength channels. This is approximately a ten-fold improvement from the 1989 flight season when NEdL was closer to 0.1 (Green et al., 1990). In the current investigation, AVIRIS data from the 2002 flight season collected over the Pavant Butte tuff cone, Tabernacle Hill tuff ring, and an associated lava flow in the Black Rock Desert of west central Utah were examined to determine how well these generally low albedo volcanic lavas and tephras could be discriminated from background materials. The Pavant Butte tuff cone was examined by the author in an earlier study with a 1989 AVIRIS dataset (Farrand and Singer,

Farrand, William H.↗
NASA NTRSDate not supplied

Materials for Power Transmission in Extreme Environments

NASA’s goal for a sustained human presence on the Moon and a future Lunar economy requires the development of novel power transmission materials for extreme environments. As an increasing number of public and private entities set their sights towards a future on the Moon, the demand for surface power will dramatically increase – potentially up to megawatt levels. A Lunar economy is envisioned to include a human habitat, manned and unmanned science exploration assets, excavation rovers and systems, and large-scale infrastructure construction such as solar arrays and power grids. A NASA trade study estimated that 1 to 3 km of power transmission lines (1 to 3 KV ac and dc) will be needed over time. Current high power and voltage SOA cables/wire can easily exceed 1 kg/m where mass is not as critical. Connectors, deployment spools and robots further increase the subsystem mass significantly increasing costs. On the other hand, advances in aeronautics provides path towards space missions. The operating environment on the Moon presents substantial risk to safe and reliable power transmission due to space weathering and degradation. These challenges include cosmic and UV radiation, extreme temperatures swings, the electrostatic Lunar exosphere, and the electrostatic and abrasive lunar regolith. The critical need for lightweight, safe and reliable power cables/wires materials is evident. In this presentation, the extreme high altitude and lunar environments and recent materials development from NASA Glenn Research Center’s High Voltage Materials team towards meeting NASA’s objectives and goals for aeronautics and space missions.

Cu/CNT conductors↗
NASA NTRS1973

Fabrication and Improvement of Lmsc's All-silica RSI

The LI-1500 and LI-900 all silica RSI materials have made the transition from laboratory to manufacturing operation. Improvements in both quality and reproducibility have been achieved. The LI-1500 material has displayed superior reliability in evaluations conducted at various facilities. The dependable performance of the material is attributed to the adherence to the stringent requirements of the numerous material, process, and product control evaluations and inspection points performed during manufacture.

Beasley, R. M.↗
NASA NTRS1975

A comparison of two rocket borne Langmuir probes having electrodes of different materials

The behavior of two types of Langmuir probes, one with electrodes made of low-sulfur stainless steel and one with electrodes made of aluminum coated with Aquadag, has been compared on two rocket flights. Each rocket payload included one Langmuir probe of each type. The electron temperatures measured with the stainless-steel electrodes were about 15% higher than the electron temperatures measured with the Aquadag-coated electrodes at 150 km on ascent and about 10% higher at 180 km. These results imply that the use of Aquadag coated electrodes or electrodes of other carefully chosen materials permits greater reliability in the measurement of electron temperatures in the ionosphere by the Langmuir probe technique.

Schutz, S. R.↗
NASA NTRS1981

Reliability achievement in high technology space systems

The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

Lindstrom, D. L.↗
NASA NTRS1986

Fatigue response of notched laminates subjected to tension-compression cyclic loads

The fatigue response of a ((0/45/90/-45)(sub s))(sub 4) T300-5208 graphite-epoxy laminate with a drilled center-hole subjected to various components of tensile and compressive cyclic loads was investigated. Damage evaluation techniques such as stiffness monitoring, penetrant-enhanced X-ray radiography, C-scan, laminate deply and residual strength measurement were used to establish the mechanisms of damage development as well as the effect of such damage on the laminate strength, stiffness and life. Damage modes consisted of transverse matrix cracks, initiating at the hole, in all plies, followed by delamination between plies of different orientation. A characteristic stiffness repsonse during cyclic loading at two load levels was identified and utilized a more reliable indicator of material and residual properties than accumulated cycles. For the load ratios of tension-compression loading, residual tensile strength increased significantly above the virgin strength early in the fatigue life and remained approximately constant to near the end of life. A technique developed for predicting delamination initiation sites along the hole boundary correlated well with experimental evidence.

Bakis, C. E.↗
NASA NTRS1988

Elevated temperature durability of ceramic materials

Fast fracture, stress rupture, and cyclic high temperature durability characterizations have been conducted for advanced silicon carbide and silicon nitride ceramics applicable to gas turbine hot section components. The fast fracture and stress rupture tests were conducted in four-point flexure at temperatures of up to 1540 C; the durability tests involved cycling specimens to temperatures of 1370 C and air quenching at 200 C for up to 3500 hrs. Materials with further reliability improvements are noted to be required for gas turbine hot section component applications.

Lindberg, Laura J.↗
NASA NTRS1989

Aging behavior and life prediction of graphite composites

This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

Ramohalli, Kumar↗
NASA NTRS1991

Component technology for stirling power converters

NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

Thieme, Lanny G.↗
NASA NTRS1992

Infrared Thermography For Welding

Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.

Gilbert, Jeffrey L.↗
NASA NTRS1991

Component technology for Stirling power converters

NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

Thieme, Lanny G.↗
NASA NTRS1993

Development of a cryogenic hydrogen maser at the NPL

A prototype Cold Hydrogen Maser (CHM) was being developed for the past year. The features of this CHM, which is designed to operate initially at 4.2 K, are the use of low loss alumina, and later sapphire, in the fabrication of the microwave cavity; possible use of superconductors for shielding; use of a cryogenic amplifier; possible coating material; and a reliable RF discharge circuit for the dissociation of hydrogen. A numerical simulation was performed to find the dimensions of the microwave cavity for the TE011 mode and the model was confirmed experimentally. The system will be used to test various wall coatings adsorbed on top of a PTFE buffer underlayer. The CHM is expected to be used as a flywheel frequency standard at the NPL with medium-term stability of one part in 10(exp 14) or better.

Mossavati, R.↗