Results for “materials evaluation” — Page 21

NASA NTRS2002

Thermal Analysis in Support of the Booster Separation Motor Crack Investigation

During a post-test inspection of a Booster Separation Motor (BSM) from a Lot Acceptance Test (LAT), a crack was noticed in the graphite throat. Since this was an out-of-family occurrence, an investigation team was formed to determine the cause of the crack. This paper will describe thermal analysis techniques used in support of this investigation. Models were generated to predict gradients in nominal motor conditions, as well as potentially anomalous conditions. Analysis was also performed on throats that were tested in the Laser Hardened Material Evaluation Laboratory (LHMEL). Some of these throats were pre-cracked, while others represented configurations designed to amplify effects of thermal stresses. Results from these analyses will be presented in this paper.

Davis, Darrell↗

NASA NTRS2003

Web-Enhanced Instruction and Learning: Findings of a Short- and Long-Term Impact Study and Teacher Use of NASA Web Resources

Over a three-year period, researchers and educators from the Pennsylvania State University (PSU), University Park, Pennsylvania, and the NASA Dryden Flight Research Center (DFRC), Edwards, California, worked together to analyze, develop, implement and evaluate materials and tools that enable teachers to use NASA Web resources effectively for teaching science, mathematics, technology and geography. Two conference publications and one technical paper have already been published as part of this educational research series on Web-based instruction and learning. This technical paper, Web-Enhanced Instruction and Learning: Findings of a Short- and Long-Term Impact Study, is the culminating report in this educational research series and is based on the final report submitted to NASA. This report describes the broad spectrum of data gathered from teachers about their experiences using NASA Web resources in the classroom. It also describes participating teachers responses and feedback about the use of the NASA Web-Enhanced Learning Environment Strategies reflection tool on their teaching practices. The reflection tool was designed to help teachers merge the vast array of NASA resources with the best teaching methods, taking into consideration grade levels, subject areas and teaching preferences. The teachers described their attitudes toward technology and innovation in the classroom and their experiences and perceptions as they attempted to integrate Web resources into science, mathematics, technology and geography instruction.

McCarthy, Marianne C.↗

NASA NTRS2003

NASA Helps Keep the Light Burning for the Saturn Car Company

The Saturn Electronics & Engineering, Inc. (Saturn) facility in Marks, Miss., that produces lamp assemblies was experiencing itermittent problems with its automotive under the hood lamps. After numerous testing and engineering efforts, technicians could not pin down the root of the problem. So Saturn contacted the NASA Technology Assistance Program (TAP) at Stennis Space Center. The Marks production facility had been experiencing intermittent problems with under the hood lamp assemblies for some time. The failure rate, at 2 percent, was unacceptable. Every effort was made to identify the problem so that corrective action could be put in place. The problem was investigated and researched by Saturn's engineering department. In addition, Saturn brought in several independent testing laboratories. Other measures included examining the switch component suppliers and auditing them for compliance to the design specifications and for surface contaminants. All attempts to identify the factors responsible for the failures were inconclusive. In an effort to get to the root of the problem, and at the recommendation of the Mississippi Department of Economic Development, Saturn contacted the NASA TAP at Stennis. The NASA Materials and Contamination Laboratory, with assistance from the Stennis Prototype Laboratory, conducted a materials evaluation study on the switch components. The laboratory findings showed the failures were caused by a build-up of carbon-based contaminants on the switch components. Saturn Electronics & Engineering, Inc., is a minority-owned provider of contract manufacturing services to a diverse global marketplace. Saturn operates manufacturing facilities globally serving the North American, European, and Asian markets. Saturn's production facility in Marks, Mississippi, produces more than 1,000,000 lamps and switches monthly. "Since the NASA recommendations were implemented, our internal failure rate for intermittency has dropped to less than .02 percent. Most importantly, we restored our high-level of customer satisfaction. Stennis provided an invaluable service to our business," Patrick said. Both NASA and Saturn were pleased with the results form this technical assistance project. The Technology Assistance Program at Stennis makes available to the public NASA technical expertise and access to lab facilities. This project provided both services with a positive outcome.

Source record↗

NASA NTRS2001

Ceiling Fires Studied to Simulate Low-Gravity Fires

A unique new way to study low-gravity flames in normal gravity has been developed. To study flame structure and extinction characteristics in low-stretch environments, a normal gravity low-stretch diffusion flame was generated using a cylindrical PMMA sample of varying large radii, as shown in the photograph. These experiments have demonstrated that low-gravity flame characteristics can be generated in normal gravity through the proper use of scaling. On the basis of this work, it is feasible to apply this concept toward the development of an Earth-bound method of evaluating material flammability in various gravitational environments from normal gravity to microgravity, including the effects of partial gravity low-stretch rates such as those found on the Moon (1/6g) or Mars (1/3g). During these experiments, the surface regression rates for PMMA were measured for the first time over the full range of flammability in air, from blowoff at high stretch, to quenching at low stretch, as plotted in the graph. The solid line drawn through the central portion of the data (3<a<100 sec-1) has a slope of unity, which indicates regression is proportional to stretch. The figure coordinates assume that the values of stretch are equivalent, whether derived from forced stretch or from buoyant stretch. The excellent correlation of the regression-rate data over the two-order-of-magnitude variation of stretch shows the reasonableness of this assumption.

Olson, Sandra L.↗

NASA NTRS2005

NARC Rayon Replacement Program for the RSRM Nozzle, Phase IV Qualification and Implementation Status

The Space Shuttle NARC Rayon Replacement Program has down-selected Enka rayon as a replacement for the obsolete NARC rayon in the nozzle carbon cloth phenolic (CCP) ablative insulators. Full qualification testing of the Enka rayon-based carbon cloth phenolic is underway, including processing, thmal/structural properties, and hot-fire subscale tests. Required thermal-structural capabilities, together with confidence in erosio/char performance in simulated and subscale hot fire tests such as Wright-Patterson Air Force Base Laser Hardened Materials Evaluation Laboratory testing, NASA-MSFC 24-inch motor tests, NASA-MSFC Solid Fuel Torch - Super Sonic Blast Tube, NASA-MSFC Plasma Torch Test Bed, ATK Thiokol Forty Pound Charge and NASA-MSFC MNASA justified the testing of the new Enka-rayon candidate on full-scale static test motors. The first RSRM full-scale static test motor nozzle, fabricated using the new Enka rayon-based CCP, was successfully demonstrated in June 2004. Two additional static test motors are planned with the new Enka rayon in the next two years along with additional A-basis property characterization. Process variation or "corner-of-the-box" testing together with cured and uncured aging studies are also planned as some of the pre-flight implementation activities with 5-year cured aging studies over-lapping flight hardware fabrication.

Haddock, M. Reed↗

NASA NTRS2005

Stirling Power Convertors Demonstrated in Extended Operation

A 110-W Stirling Radioisotope Generator (SRG110) is being developed by Lockheed Martin Astronautics of Valley Forge, Pennsylvania, under contract to the Department of Energy of Germantown, Maryland. The generator will be a high-efficiency electric power source for NASA space exploration missions that can operate in the vacuum of deep space or in a gaseous atmosphere, such as on the surface of Mars. The generator converts heat supplied by the decay of a plutonium heat source into electric power for the spacecraft. In support of the SRG110 project, the NASA Glenn Research Center has established a technology effort that will provide some of the key data to ensure a successful transition to flight for what will be the first dynamic power system to be used in space. High system efficiency is obtained through the use of free-piston Stirling power-conversion technology. Glenn tasks include in-house testing of Stirling convertors and controllers, materials evaluation and heater head life assessment, structural dynamics, evaluation of electromagnetic interference, assessment of organics, and reliability analysis. There is also an advanced technology effort that is complementary to the near-term technology effort, intended to reduce the mass of the Stirling convertor and increase efficiency.

Schreiber, Jeffrey G.↗

NASA NTRS2009

Overview of CEV Thermal Protection System Seal Development

NASA GRC supporting design, development, and implementation of numerous seal systems for the Orion CEV: a) HS-to-BS interface. b) Compression pad. HS-to-BS Interface Seal System: a) design has evolved as a result of changes with the CEV TPS. b) Seal system is currently under development/evaluation. Coupon level tests, Arc jet tests, and Validation test development. Compression Pad: a) Finalizing design options. b) Evaluating material candidates.

DeMange, Jeff↗

NASA NTRS2011

Metallographic Preparation of Space Shuttle Reaction Control System Thruster Electron Beam Welds for Electron Backscatter Diffraction

A Space Shuttle Reaction Control System (RCS) thruster failed during a firing test at the NASA White Sands Test Facility (WSTF), Las Cruces, New Mexico. The firing test was being conducted to investigate a previous electrical malfunction. A number of cracks were found associated with the fuel closure plate/injector assembly (Fig 1). The firing test failure generated a flight constraint to the launch of STS-133. A team comprised of several NASA centers and other research institutes was assembled to investigate and determine the root cause of the failure. The JSC Materials Evaluation Laboratory was asked to compare and characterize the outboard circumferential electron beam (EB) weld between the fuel closure plate (Titanium 6Al-4V) and the injector (Niobium C-103 alloy) of four different RCS thrusters, including the failed RCS thruster. Several metallographic challenges in grinding/polishing, and particularly in etching were encountered because of the differences in hardness, ductility, and chemical resistance between the two alloys and the bimetallic weld. Segments from each thruster were sectioned from the outboard weld. The segments were hot-compression mounted using a conductive, carbon-filled epoxy. A grinding/polishing procedure for titanium alloys was used [1]. This procedure worked well on the titanium; but a thin, disturbed layer was visible on the niobium surface by means of polarized light. Once polished, each sample was micrographed using bright field, differential interference contrast optical microscopy, and scanning electron microscopy (SEM) using a backscatter electron (BSE) detector. No typical weld anomalies were observed in any of the cross sections. However, areas of large atomic contrast were clearly visible in the weld nugget, particularly along fusion line interfaces between the titanium and the niobium. This prompted the need to better understand the chemistry and microstructure of the weld (Fig 2). Energy Dispersive X-Ray Spectroscopy (EDS) was used to confirm the chemical composition of the variations in contrast in these areas. Niobium alloys generally require exposure to more aggressive chemical reagents than titanium alloys for etching because of niobium s chemical resistance; therefore, the titanium portion of the sample was etched first. A five second immersion in Kroll s reagent revealed a general microstructure on the titanium portion of the sample; however, the titanium heat affected zone closest to the weld, was over-etched due to higher concentrations of refined grains and an increase in eta-phase. The Kroll s etchant also revealed some microstructure in the weld nugget itself; the niobium portion of the sample remained unetched.

Martinez, James↗

NASA NTRS2018

A Thermal Imaging Instrument with Uncooled Detectors

In this work, we performed an instrument concept study for sustainable thermal imaging over land with uncooled detectors. We evaluated two different uncooled detector technologies uncooled microbolometers and thermopiles. We have also evaluated materials for use in in a uncooled thermopile detector concept.

Thermal↗

NASA NTRS2019

An Investigation into the Grain Structure of Impact Ice

To design effective anti-icing and de-icing technology for aircraft, scientists and engineers must obtain a fundamental understanding of the microstructural characteristics of impact ice. This study investigates the effects of icing parameters, such as airspeed and liquid water content (LWC), on impact ice microstructure near the interface to a metal substrate. Ice samples were accreted in the NASA Glenn Icing Research Tunnel and tested in the NASA Revolutionary Icing Materials Evaluation Laboratory. A microtome was used to shave down the ice to a thickness of < 1 mm for examination under a microscope. Samples were imaged at multiple magnifications using bright field imaging. The average grain size was determined for each sample in accordance with ASTM standard methods, and relationships between airspeed, LWC, and grain size were identified. It was observed that the average grain area in a given cross-section was linearly related to the distance of the cross-section from the metal surface. Finally, the effects of annealing and sublimation on the microstructure were also explored. Results show significant variation in the grain structure, suggesting a means by which icing condition influences adhesion strength.

grain↗

NASA NTRSDate not supplied

Integral Channel Nozzles and Heat Exchangers using Additive Manufacturing Directed Energy Deposition NASA HR-1 Alloy

Heat exchangers for use in propulsion applications are very critical components because they must be efficient, compact and light and often operate with working fluids at extreme temperatures or pressures or both. Various components and systems use heat exchangers such as combustion chambers of gas turbines and internal combustion engines, fuel cells (air supply and thermal management), electric batteries (thermal management), evaporators and recuperators of waste-heat-to-power systems, and rocket engines. Even if the results are more generally applicable, the heat exchangers applications to which this study is more closely related are regeneratively cooled rocket nozzles and chambers, and repressurization systems for the launch vehicles. These components are often thin-walled and contain pressurized fluids, like propellants at cryogenic or elevated temperatures. Given that the environments that these propulsion components must endure are challenging, the manufacturing to meet these specifications often require long lead times due to specialty processes and unique tooling associated with the combined thin-wall integral channel and large-scale structures. Additive manufacturing (AM) offers programmatic advantages for reduction in processing time and cost in addition to various technical advantages, including the possibility to achieve enhanced hardware complexity targeted to superior performance, part consolidation, and the capability of processing of novel alloys. While AM is already being utilized for heat exchanger components in propulsion applications, almost all these AM components are made by means of Laser Powder Bed Fusion (L-PBF). L-PBF allows for fine features but is rather limited with respect to the overall size of the components that can be manufactured. Recent developments are maturing the Laser Powder Directed Energy Deposition (LP-DED) process which may be used, for example, to make integral channel thin-wall regeneratively-cooled rocket nozzles with diameters greater than 1 m. This paper highlights some integral channel heat exchanger demonstrator hardware applications of LP-DED, as well as the characterization of this process in combination with the use of the NASA HR-1 alloy. To properly utilize LP-DED for heat exchanger manufacturing, various aspects are being characterized such as geometry limitations, measurement of surface texture and geometric angled surfaces, surface enhancements for internal channels, and material evaluation. NASA HR-1 (FeNi-Cr) is a high strength hydrogen resistant superalloy developed for use in aerospace applications, such as heat exchangers. Some aspects and considerations about the design of heat exchangers are summarized together with data relevant to LP-DED manufacturing in combination with the NASA HR-1 alloy. Microchannels were successful deposited down to 2.54 mm and 1 mm wall thickness, wall angles of 30°, both with high reproducibility. It was also found that the areal surface roughness is highly dependent on the size of the powder feedstock used for deposition. The characterization of these LP-DED features is critical for fluid flow and heat transfer predictions as it can be exploited to enhance heat transfer at the cost of increased pressure drop.

Additive Manufacturing↗

NASA NTRSDate not supplied

Integral Channel Nozzles and Heat Exchangers using Additive Manufacturing Directed Energy Deposition NASA HR-1 Alloy

Heat exchangers for use in propulsion applications are very critical components because they must be efficient, compact and light and often operate with working fluids at extreme temperatures or pressures or both. Various components and systems use heat exchangers such as combustion chambers of gas turbines and internal combustion engines, fuel cells (air supply and thermal management), electric batteries (thermal management), evaporators and recuperators of waste-heat-to-power systems, and rocket engines. Even if the results are more generally applicable, the heat exchangers applications to which this study is more closely related are regeneratively cooled rocket nozzles and chambers, and repressurization systems for the launch vehicles. These components are often thin-walled and contain pressurized fluids, like propellants at cryogenic or elevated temperatures. Given that the environments that these propulsion components must endure are challenging, the manufacturing to meet these specifications often require long lead times due to specialty processes and unique tooling associated with the combined thin-wall integral channel and large-scale structures. Additive manufacturing (AM) offers programmatic advantages for reduction in processing time and cost in addition to various technical advantages, including the possibility to achieve enhanced hardware complexity targeted to superior performance, part consolidation, and the capability of processing of novel alloys. While AM is already being utilized for heat exchanger components in propulsion applications, almost all these AM components are made by means of Laser Powder Bed Fusion (L-PBF). L-PBF allows for fine features but is rather limited with respect to the overall size of the components that can be manufactured. Recent developments are maturing the Laser Powder Directed Energy Deposition (LP-DED) process which may be used, for example, to make integral channel thin-wall regeneratively-cooled rocket nozzles with diameters greater than 1 m. This paper highlights some integral channel heat exchanger demonstrator hardware applications of LP-DED, as well as the characterization of this process in combination with the use of the NASA HR-1 alloy. To properly utilize LP-DED for heat exchanger manufacturing, various aspects are being characterized such as geometry limitations, measurement of surface texture and geometric angled surfaces, surface enhancements for internal channels, and material evaluation. NASA HR-1 (FeNi-Cr) is a high strength hydrogen resistant superalloy developed for use in aerospace applications, such as heat exchangers. Some aspects and considerations about the design of heat exchangers are summarized together with data relevant to LP-DED manufacturing in combination with the NASA HR-1 alloy. Microchannels were successful deposited down to 2.54 mm and 1 mm wall thickness, wall angles of 30°, both with high reproducibility. It was also found that the areal surface roughness is highly dependent on the size of the powder feedstock used for deposition. The characterization of these LP-DED features is critical for fluid flow and heat transfer predictions as it can be exploited to enhance heat transfer at the cost of increased pressure drop.

additive manufacturing↗

NASA NTRS2023

Effects of Strain Rate and Surface Finish on Tensile Properties in High Pressure Hydrogen — A Case Study for LP-DED NASA HR-1

NASA has advanced NASA HR-1 as a solution for liquid rocket engine components that operate in hydrogen rich environments using various AM techniques. The NASA HR-1 for AM applications was specifically formulated for high ductility in high pressure gaseous hydrogen environment in addition to high strength and low cycle fatigue (LCF) resistance. NASA HR-1 meets materials requirements for liquid rocket engine components, including good hydrogen resistance, high conductivity, good LCF performance, and high elongation and strength for components in medium heat flux environments. NASA has completed fabrication of several subscale and full-scale channel wall nozzles in LP-DED NASA HR-1 and completed hot-fire testing. This includes refinement of the process to produce thin-walls and various channel geometries to meet the requirements for channel wall nozzle applications. The main objective of this investigation is to better understand the effects of tensile test strain rate and specimen surface finish on the amount of tensile ductility degradation in high pressure gaseous hydrogen environments. Performing smooth tensile tests in high pressure hydrogen and nitrogen environments can serve as a rapid and economical screening method to determine the relative susceptibility of materials to HEE. This paper presents the tensile test results for LP-DED NASA HR-1 in hydrogen and details the material evaluation on the effects of strain rate and surface finish condition on surface cracking behavior and fracture characteristics. The resistance to HEE for LP-DED NASA HR-1 and the wrought alloy is compared under the same testing conditions. Loss of tensile ductility is quantified in terms of changes in elongation at failure in hydrogen to compare HEE susceptibility. The most suitable strain rate and specimen surface finish condition for future HEE screening testing at MSFC are recommended.

Additive manufacturing↗

NASA NTRS2008

Microwave Nondestructive Evaluation of Dielectric Materials with a Metamaterial Lens

A novel microwave Nondestructive Evaluation (NDE) sensor was developed in an attempt to increase the sensitivity of the microwave NDE method for detection of defects small relative to a wavelength. The sensor was designed on the basis of a negative index material (NIM) lens. Characterization of the lens was performed to determine its resonant frequency, index of refraction, focus spot size, and optimal focusing length (for proper sample location). A sub-wavelength spot size (3 dB) of 0.48 lambda was obtained. The proof of concept for the sensor was achieved when a fiberglass sample with a 3 mm diameter through hole (perpendicular to the propagation direction of the wave) was tested. The hole was successfully detected with an 8.2 cm wavelength electromagnetic wave. This method is able to detect a defect that is 0.037 lambda. This method has certain advantages over other far field and near field microwave NDE methods currently in use.

Shreiber, Daniel↗

NASA NTRS1995

Evaluation of certain material films flown on the Space Shuttle Mission 46, EOIM-3 experiment

Nine film samples were carried aboard the STS-46 Atlantis shuttle to complement the 'Evaluation of Oxygen Interaction with Materials (EOIM-III)' experiment to evaluate the effects of atomic oxygen on materials and to monitor the gaseous environment in the shuttle bay. The morphological changes of the samples produced by the atomic oxygen fluence of 2.07E-20 atoms/sq cm have been reported. The changes have been verified using X-ray Photoelectron Spectrometer (XPS) also known as Electron Spectroscopy for Chemical Analysis (ESCA), gravimetric measurements, microscopic observations and thermo-optical measurements. The samples including Kapton, Tefzel, Aclar, Polyacrylonitrile film, and Llumalloy films have been characterized by their oxygen reaction efficiency on the basis of their erosion losses and the fluence. Those efficiencies have been compared with results from other similar experiments, when available. The efficiencies of the samples are all in the range of E-24 gm/atom.

Scialdone, John↗

NASA NTRS1983

Orbiter TPS development and certification testing at the NASA/JSC 10 MW Atmospheric Reentry Materials and Structures Evaluation Facility

Thermal performance of the Space Shuttle Orbiter Thermal Protection System (TPS) has been verified by extensive ground testing at the NASA/JSC 10 MW Atmospheric Reentry Materials and Structures Evaluation Facility (ARMSEF). Major test programs have included current TPS materials (RSI, RCC and ablators) and advanced TPS materials (AFRSI and FRCI-12). Testing by electrically heating a gas mixture simulating air and expanding it (supersonically or hypersonically) through channel or conical nozzles has produced simulated thermal and pressure environments on models representative of the Orbiter TPS acreage and penetration regions. Tests have established Orbiter TPS thermal design requirements, verified Orbiter TPS thermal performance, and supported Orbiter TPS flight anomaly investigations and resolutions.

Rochelle, W. C.↗

DOE OSTI2021

Evaluation of the Los Alamos Nuclear Material Packaging Risk Ranking Method

Repackaging nuclear material into robust containers to protect workers and the public has been ongoing at LANL and around the DOE complex for nearly two decades. The number of containers at LANL is around 5,000; limited resources for repackaging material has led to extended repackaging campaigns and the need to prioritize repackaging. Various methodologies have been used to prioritize the repackaging efforts and to demonstrate progress in risk reduction over time (e.g., Boerigter, 1997). The 2000-1 DNFSB recommendation recognized the limited DOE resources for repackaging, and acknowledged the need to “prioritize and schedule tasks to be undertaken with available funds according to consideration of risks.” Later, in DNFSB recommendation 2005-1, in addition to recommending that DOE develop a packaging standard, the Board recommended that “Characterization information should also be used to develop a surveillance program prioritized according to expected material and container risk (including, for example, material type, material form, and the age and type of container).” In response to requests and recommendations from the DOE and DNSFB to prioritize according to worker risk, a risk ranking method based on the potential consequence of dropping a container from 3 meters was developed in 2007 (Smith, 2007) and updated in 2014 (Hoffman, 2014). Various LANL implementation plans for repackaging were developed over the years using this methodology (Stone, 2014). Currently, this method is utilized in conjunction with an algorithm to mitigate programmatic risk to prioritize container repackaging and material processing (Prochnow, 2015). The purpose of this study is to document how the current risk ranking method works, how it is used and potential limitations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

NASA NTRS1975

Fire-resistant aircraft materials development and evaluation program

An aircraft flammability program was undertaken to utilize spacecraft developed fire-resistant materials to improve passenger safety and decrease losses from unattended fires in commercial aircraft. Five full-scale aircraft flammability tests were performed to evaluate the effectiveness of improved fire-resistant materials by comparing their burning characteristics with those of pre-1968 aircraft materials.

Bricker, R. W.↗