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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Vaccum Gas Tungsten Arc Welding, phase 1

This two year program will investigate Vacuum Gas Tungsten Arc Welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. VGTAW appears to offer a significant improvement in weldability because of the clean environment and lower heat input needed. The overall objective of the program is to develop the VGTAW technology and implement it into a manufacturing environment that will result in lower cost, better quality and higher reliability aerospace components for the space shuttle and other NASA space systems. Phase 1 of this program was aimed at demonstrating the process's ability to weld normally difficult-to-weld materials. Phase 2 will focus on further evaluation, a hardware demonstration and a plan to implement VGTAW technology into a manufacturing environment. During Phase 1, the following tasks were performed: (1) Task 11000 Facility Modification - an existing vacuum chamber was modified and adapted to a GTAW power supply; (2) Task 12000 Materials Selection - four difficult-to-weld materials typically used in the construction of aerospace hardware were chosen for study; (3) Task 13000 VGTAW Experiments - welding experiments were conducted under vacuum using the hollow tungsten electrode and evaluation. As a result of this effort, two materials, NARloy Z and Incoloy 903, were downselected for further characterization in Phase 2; and (4) Task 13100 Aluminum-Lithium Weld Studies - this task was added to the original work statement to investigate the effects of vacuum welding and weld pool vibration on aluminum-lithium alloys.

Weeks, J. L.↗
NASA NTRS1972

Developmental status of thermionic materials.

Description of the reference materials selected for the major components of the unit cell of a thermionic pile element (TFE), the out-of-pile and in-pile test results, and current efforts for improving the life and performance of thermionic fuel elements. The component materials are required to withstand the fuel burnup and fast neutron fluence dictated by the thermionic reactor system. Tungsten was selected as the cladding material because of its compatibility with both the carbide and the oxide fuel materials. Niobium was selected as the collector material because its thermal expansion coefficient matches closely with that of the thin aluminum oxide layer used to electrically insulate the collector from the TFE sheath. An unfueled converter has performed stably over 41,000 hr. Accelerated irradiation tests have attained burnups equivalent to that for 40,000 hr of the thermionic reactor under consideration.

Yang, L.↗
NASA NTRSDate not supplied

Broad Compatibility Study of Polymeric Materials with Ionic Silver Biocide, Part I

NASA is considering ionic silver as a residual biocide for use in potable water systems being planned for future exploration spacecraft. Compatibility of the biocide with the system’s wetted-materials of construction remains a challenge. Due to the relatively inert nature of plastics, their use in varied water system applications may offer unique opportunities to address many biocide compatibility issues. A 2020 ICES paper described a “Stage 1” assessment of several polymeric materials, in which coupons having a 2 cm 1 surface to volume ratio were exposed to solutions of 400 parts per billion (ppb) aqueous silver fluoride (AgF) for one week. In this current paper, additional Stage 1 test results are presented for select epoxies and lubricants applied on silver-inert substrates. The coupon exposure studies were also expanded to a duration of 5 weeks for the “well-behaved” Stage 1 plastics previously reported: those exhibiting silver losses above 10% and less than 50%. For this type of Stage 2 testing, silver biocide solution samples are taken from three separate (and not previously-sampled) coupon containers after 3 days, and 2, 3, 4, and 5 weeks of exposure. "Very well-behaved" Stage 1 plastics will be tested in the same manner over one year, with longer sample intervals; early-period results are included here. In addition, for select materials, the coupons were “aged” by refilling test containers with fresh AgF and observing the respective silver uptake over similar Stage 2 test durations. For all test series, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and ion-selective electrode (ISE) analyses were used to determine total and ionic silver (Ag+) concentrations, respectively. Additional sample analyses for Stage 2 tests includes total organic carbon (TOC), pH, conductivity, and oxidation-reduction potential (ORP). Ultimately, these early compatibility studies will be used to guide future material selections for developing silver biocide-compatible spacecraft water systems.

Silver Biocide↗
NASA NTRS1971

Specialized testing and evaluation of space-suit materials

The selection of nonmetallic materials used in the Apollo space suits is discussed. The specialized test program to determine the flammability of selected space suit materials is described. Emphasis is placed on the equipment used to test and qualify the space suit materials and subassemblies for operation in the deep space environment.

Ballentine, T. J.↗
NASA NTRS1984

SP-100 space nuclear power system

A baseline design concept for a 100 kWe nuclear reactor space power system is described. The concept was developed under contract from JPL as part of a joint program of the DOE, DOD, and NASA. The major technical and safety constraints influencing the selection of reactor operating parameters are discussed. A lithium-cooled compact fast reactor was selected as the best candidate system. The material selected for the thermoelectric conversion system was silicon germanium (SiGe) with gallium phosphide doping. Attention is given to the improved safety of the seven in-core control rod configuration.

Given, R. W.↗
NASA NTRS2007

Analyzing Responses of Chemical Sensor Arrays

NASA is developing a third-generation electronic nose (ENose) capable of continuous monitoring of the International Space Station s cabin atmosphere for specific, harmful airborne contaminants. Previous generations of the ENose have been described in prior NASA Tech Briefs issues. Sensor selection is critical in both (prefabrication) sensor material selection and (post-fabrication) data analysis of the ENose, which detects several analytes that are difficult to detect, or that are at very low concentration ranges. Existing sensor selection approaches usually include limited statistical measures, where selectivity is more important but reliability and sensitivity are not of concern. When reliability and sensitivity can be major limiting factors in detecting target compounds reliably, the existing approach is not able to provide meaningful selection that will actually improve data analysis results. The approach and software reported here consider more statistical measures (factors) than existing approaches for a similar purpose. The result is a more balanced and robust sensor selection from a less than ideal sensor array. The software offers quick, flexible, optimal sensor selection and weighting for a variety of purposes without a time-consuming, iterative search by performing sensor calibrations to a known linear or nonlinear model, evaluating the individual sensor s statistics, scoring the individual sensor s overall performance, finding the best sensor array size to maximize class separation, finding optimal weights for the remaining sensor array, estimating limits of detection for the target compounds, evaluating fingerprint distance between group pairs, and finding the best event-detecting sensors.

Zhou, Hanying↗
NASA NTRS2011

Factors Influencing Dwell Fatigue Cracking in Notches of Powder Metallurgy Superalloys

The influences of heat treatment and cyclic dwells on the notch fatigue resistance of powder metallurgy disk superalloys were investigated for low solvus high refractory (LSHR) and ME3 disk alloys. Disks were processed to produce material conditions with varied microstructures and associated mechanical properties. Notched specimens were first subjected to baseline dwell fatigue cycles having a dwell at maximum load, as well as tensile, stress relaxation, creep rupture, and dwell fatigue crack growth tests at 704 C. Several material heat treatments displayed a bimodal distribution of fatigue life with the lives varying by two orders-of-magnitude, while others had more consistent fatigue lives. This response was compared to other mechanical properties, in search of correlations. The wide scatter in baseline dwell fatigue life was observed only for material conditions resistant to stress relaxation. For selected materials and conditions, additional tests were then performed with the dwells shifted in part or in total to minimum tensile load. The tests performed with dwells at minimum load exhibited lower fatigue lives than max dwell tests, and also exhibited early crack initiation and a substantial increase in the number of initiation sites. These results could be explained in part by modeling evolution of peak stresses in the notch with continued dwell fatigue cycling. Fatigue-environment interactions were determined to limit life for the fatigue cycles with dwells.

Gabb, T. P.↗
NASA NTRSDate not supplied

Lightweight Thrust Chamber Composite Overwrap Lessons Learned

Filament winding a polymer/carbon fiber composite overwrap onto an additively manufactured copper combustion chamber will allow it to act as a light-weight structural jacket, significantly reducing weight for high pressure thrust chamber assemblies and reducing overall cost and fabrication schedules. Chamber assemblies for 2k lb. and 7k lb. of thrust have been successfully tested at NASA’s Marshall Space Flight Center. Multiple lessons were learned throughout the overwrap process development and manufacturing trials. The lessons learned on small scale hardware will guide further composite manufacturing technologies and enable a progression to larger scale assemblies with greater structural loads. Material performance requirements, manufacturing process development, and surface preparation were evaluated during the small chamber trials, with the broad thermal requirements of the resin being the primary driver for material selection and processing. Both epoxy and bismaleimide materials were evaluated with respect to both performance in the hot-fire test and ease of fabrication. Separately, surface preparation procedures were studied with the goal of providing a smooth chamber surface to promote a non-bonded overwrap. The recent testing of the 7k trust chamber has provided data in Non-Destructive Evaluation (NDE) and processing in order to continue to evaluate the performance requirements stated.

composite overwrap↗
NASA NTRS2000

Development of the Spacecraft Materials Selector Expert System

A specific knowledge base to evaluate the on-orbit performance of selected materials on spacecraft is being developed under contract to the NASA SEE program. An artificial intelligence software package, the Boeing Expert System Tool (BEST), contains an inference engine used to operate knowledge bases constructed to selectively recall and distribute information about materials performance in space applications. This same system is used to make estimates of the environmental exposures expected for a given space flight. The performance capabilities of the Spacecraft Materials Selector (SMS) knowledge base are described in this paper. A case history for a planned flight experiment on ISS is shown as an example of the use of the SMS, and capabilities and limitations of the knowledge base are discussed.

Pippin, H. G.↗
NASA NTRS2013

Granular Media-Based Tunable Passive Vibration Suppressor

and vibration suppression device is composed of statically compressed chains of spherical particles. The device superimposes a combination of dissipative damping and dispersive effects. The dissipative damping resulting from the elastic wave attenuation properties of the bulk material selected for the granular media is independent of particle geometry and periodicity, and can be accordingly designed based on the dissipative (or viscoelastic) properties of the material. For instance, a viscoelastic polymer might be selected where broadband damping is desired. In contrast, the dispersive effects result from the periodic arrangement and geometry of particles composing a linear granular chain. A uniform (monatomic) chain of statically compressed spherical particles will have a low-pass filter effect, with a cutoff frequency tunable as a function of particle mass, elastic modulus, Poisson fs ratio, radius, and static compression. Elastic waves with frequency content above this cutoff frequency will exhibit an exponential decay in amplitude as a function of propagation distance. System design targeting a specific application is conducted using a combination of theoretical, computational, and experimental techniques to appropriately select the particle radii, material (and thus elastic modulus and Poisson fs ratio), and static compression to satisfy estimated requirements derived for shock and/or vibration protection needs under particular operational conditions. The selection of a chain of polymer spheres with an elastic modulus .3 provided the appropriate dispersive filtering effect for that exercise; however, different operational scenarios may require the use of other polymers, metals, ceramics, or a combination thereof, configured as an array of spherical particles. The device is a linear array of spherical particles compressed in a container with a mechanism for attachment to the shock and/or vibration source, and a mechanism for attachment to the article requiring isolation (Figure 1). This configuration is referred to as a single-axis vibration suppressor. This invention also includes further designs for the integration of the single-axis vibration suppressor into a six-degree-of-freedom hexapod "Stewart"mounting configuration (Figure 2). By integrating each singleaxis vibration suppressor into a hexapod formation, a payload will be protected in all six degrees of freedom from shock and/or vibration. Additionally, to further enable the application of this device to multiple operational scenarios, particularly in the case of high loads, the vibration suppressor devices can be used in parallel in any array configuration.

Dillon, Robert P.↗
NASA NTRS1975

On development of a sealed bearing for space suits

The work to correct several design deficiencies present in the bearings used in the orbital extravehicular spacesuit is reported. These deficiencies included: difficult stitch-on interface between fabric and outer race; a tendency for the clamping threads to seize; and, most importantly, the failure of the sealing surfaces (Teflon seat, Delrin seal) to maintain integrity with cycling. The first problem was corrected by raising the stitch-on holes so as to be more accessible. The seizing was eliminated by changing to a coarser thread, from 32/inch to 24/inch. The solution to the sealing problem required a materials evaluation, candidate material selection, and adhesive evaluation (for bonding the seat material to the outer race) and bench-cycling of candidate seal/seat combinations. The final configuration, successfully bench-cycled and delivered to NASA, is shown.

Rayfield, J.↗
NASA NTRS1992

Flush Mounting Of Thin-Film Sensors

Technique developed for mounting thin-film sensors flush with surfaces like aerodynamic surfaces of aircraft, which often have compound curvatures. Sensor mounted in recess by use of vacuum pad and materials selected for specific application. Technique involves use of materials tailored to thermal properties of substrate in which sensor mounted. Together with customized materials, enables flush mounting of thin-film sensors in most situations in which recesses for sensors provided. Useful in both aircraft and automotive industries.

Moore, Thomas C., Sr.↗
NASA NTRS1993

Current technologies for waverider aircraft

'Waverider' hypersonic vehicle configuration-related technologies are presently discussed for both the Mach 4-7 and Mach 8-12 speed regimes. These technologies encompass engine cycle selection, propulsion system integration, thermal management, structural design, materials selection, and stability/control. The integration of the propulsion system may require novel techniques for efficient blending of inlet and nozzle flows with forebody and afterbody contours.

Hagseth, Paul E.↗
NASA NTRSDate not supplied

Lightweight Thrust Chamber Composite Overwrap Lessons Learned

The manufacturing, design, and analysis of filament wound carbon fiber/polymer composite overwraps for additively manufactured, copper combustion chambers are a critical part of NASA’s Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) project. Ideally, the composite overwrap acts as a light-weight structural jacket and allows significant weight reduction of the high pressure thrust chamber assembly, reduction of overall cost, and reduced fabrication schedules. Chamber assemblies for 2000 lb. (2k) and 7000 lb. (7k) of thrust have been successfully tested at NASA’s Marshall Space Flight Center. Multiple lessons were learned throughout the overwrap process development and manufacturing trials. The lessons learned on small scale hardware, such as the 2k and 7k chambers, will guide further composite manufacturing technologies and enable a progression to larger scale assemblies with greater structural loads. Material performance requirements, manufacturing process development, and surface preparation were evaluated during the small chamber trials, with the broad thermal requirements of the resin being the primary driver for material selection and processing. Both epoxy and bismaleimide (BMI) materials were evaluated with respect to both performance in the hot-fire test and ease of fabrication. Separately, surface preparation procedures were studied with the goal of providing a smooth chamber surface to promote a non-bonded overwrap. Recent testing of the 7k trust chamber has provided data in Non-Destructive Evaluation (NDE) and processing in order to continue to evaluate the performance requirements stated.

Allison Clark↗
NASA NTRS2026

Improvement of Odor Control for the UWMS Hard-Sided Fecal Canister and the Alternate Fecal Canister

On longer range exploration missions, the mass and volume of critical hardware and consumables required to support crew will pose a big stowage challenge. This includes the hardware for the collection and storage of human metabolic solid waste. The amount of stowage needed for this hardware both before (empty) and after (full) use will be a significant burden on the overall spacecraft habitable volume, layout, and design. To help with this challenge, the National Aeronautics and Space Administration (NASA) Mars Campaign Office (MCO) Logistics Reduction (LR) Portfolio has developed a collapsible canister for the collection and containment of fecal deposits. The Alternate Fecal Canister (AFC) is a collapsible alternative to the exploration toilet Hard-sided Fecal Canister (HFC). The AFC in its empty state has a volumetric benefit to smaller vehicles on longer missions. The current designs for HFC and AFC were tested with human fecal material for odor containment at White Sands Test Facility (WSTF) where the tests on both were unsuccessful. The source of the lack of containment was isolated to a gasket used on both HFC and AFC. The gasket used was found to be open cell in design. This paper provides a summary of the materials selection and testing process to identify a replacement gasket material with the intention to replace the gaskets on both existing units as well as incorporate it into the designs going forward for future builds for exploration. Details will be provided on the design of the canisters interface with the odor bacteria lid which led to the selection of the thickness of the desired replacement. Finally, the paper will provide an update on the testing in advance of a return to WSTF for final testing and detail plans to complete testing and perform a demonstration on ISS with UWMS.

ECLSS↗
NASA NTRS2026

Improvement of Odor Control for the UWMS Hard-Sided Fecal Canister and the Alternate Fecal Canister

On longer range exploration missions, the mass and volume of critical hardware and consumables required to support crew will pose a big stowage challenge. This includes the hardware for the collection and storage of human metabolic solid waste. The amount of stowage needed for this hardware both before (empty) and after (full) use will be a significant burden on the overall spacecraft habitable volume, layout, and design. To help with this challenge, the National Aeronautics and Space Administration (NASA) Mars Campaign Office (MCO) Logistics Reduction (LR) Portfolio has developed a collapsible canister for the collection and containment of fecal deposits. The Alternate Fecal Canister (AFC) is a collapsible alternative to the exploration toilet Hard-sided Fecal Canister (HFC). The AFC in its empty state has a volumetric benefit to smaller vehicles on longer missions. The current designs for HFC and AFC were tested with human fecal material for odor containment at White Sands Test Facility (WSTF) where the tests on both were unsuccessful. The source of the lack of containment was isolated to a gasket used on both HFC and AFC. The gasket used was found to be open cell in design. This paper provides a summary of the materials selection and testing process to identify a replacement gasket material with the intention to replace the gaskets on both existing units as well as incorporate it into the designs going forward for future builds for exploration. Details will be provided on the design of the canisters interface with the odor bacteria lid which led to the selection of the thickness of the desired replacement. Finally, the paper will provide an update on the testing in advance of a return to WSTF for final testing and detail plans to complete testing and perform a demonstration on ISS with UWMS.

Toilet↗
NASA NTRS1975

Seals

Seal configurations generally found in fluid systems are given. Special attention is given to material selection and the process for achieving a seal. Seal material characteristics including wear resistance, creep, and cold flow properties are discussed.

Source record↗
NASA NTRS1991

Advanced materials for space nuclear power systems

The overall philosophy of the research was to develop and characterize new high temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites for heat rejection fins, and tungsten fiber reinforced niobium matrix composites for fuel containment and structural supports considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications.

Titran, Robert H.↗