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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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

An experimental study of the mechanism of failure of rocks under borehole jack loading

Laboratory and field tests with an experimental jack and an NX-borehole jack are reported. The following conclusions were made: Under borehole jack loading, a circular opening in a brittle solid fails by tensile fracturing when the bearing plate width is not too small. Two proposed contact stress distributions can explain the mechanism of tensile fracturing. The contact stress distribution factor is a material property which can be determined experimentally. The borehole tensile strength is larger than the rupture flexural strength. Knowing the magnitude and orientation of the in situ stress field, borehole jack test results can be used to determine the borehole tensile strength. Knowing the orientation of the in situ stress field and the flexural strength of the rock substance, the magnitude of the in situ stress components can be calculated. The detection of very small cracks is essential for the accurate determination of the failure loads which are used in the calculation of strengths and stress components.

Van, T. K.↗
NASA NTRS2000

Micromechanical Characterization and Texture Analysis of Direct Cast Titanium Alloys Strips

This research was conducted to determine a post-processing technique to optimize mechanical and material properties of a number of Titanium based alloys and aluminides processed via Melt Overflow Solidification Technique (MORST). This technique was developed by NASA for the development of thin sheet titanium and titanium aluminides used in high temperature applications. The materials investigated in this study included conventional titanium alloy strips and foils, Ti-1100, Ti-24Al-11Nb (Alpha-2), and Ti-48Al-2Ta (Gamma). The methodology used included micro-characterization, heat-treatment, mechanical processing and mechanical testing. Characterization techniques included optical, electron microscopy, and x-ray texture analysis. The processing included heat-treatment and mechanical deformation through cold rolling. The initial as-cast materials were evaluated for their microstructure and mechanical properties. Different heat-treatment and rolling steps were chosen to process these materials. The properties were evaluated further and a processing relationship was established in order to obtain an optimum processing condition. The results showed that the as-cast material exhibited a Widmanstatten (fine grain) microstructure that developed into a microstructure with larger grains through processing steps. The texture intensity showed little change for all processing performed in this investigation.

Source record↗
DOE OSTI2023

Epitaxial Design of Complex Nickelates as Electrocatalysts for the Oxygen Evolution Reaction

Abstract The oxygen evolution reaction (OER) is a crucial process in electrochemical water splitting, a promising technology to renewably yield hydrogen gas from water. Designing and developing earth‐abundant, efficient, and stable OER electrocatalysts to replace the most widely used but scarce RuO 2 and IrO 2 are thus of critical interest. Recently, ABO 3 ‐structured perovskite oxides, especially rare‐earth nickelates, are extensively studied for their potential use as OER electrocatalysts. In particular, the epitaxial synthesis of complex oxide thin films allows flexible and precise control over the materials so that their structure–stability–property relationships can be established. Using nickelate thin films as model systems, this review illustrates how epitaxial design allows researchers to test different hypotheses and proposed descriptors, as well as formulate new design principles. Following a brief introduction to the background of OER mechanisms, proposed activity descriptors, and synthesis methods, various epitaxial design strategies are surveyed including strain tuning, composition control, surface termination/orientation selection, defect engineering, and interface design. These have led to precise control over the atomic structures and electronic properties of nickelates which in turn determine their electrochemical performance. Finally, the remaining challenges and perspectives toward a deeper understanding and use of complex oxides as OER catalysts are discussed.

Choi, Min‐Ju↗
NASA NTRS2026

Artemis Suit Material Effects of Calendaring Woven Fabrics on Dust Resistance

This paper presents one element of an ongoing NASA technology-infusion effort to design, fabricate, and test a new outer shell fabric for a lunar Extravehicular Activity (EVA) space suit, a critical component of sustained lunar exploration. A primary challenge for suit textiles is preventing lunar dust, which is highly abrasive, electrostatically charged, and capable of infiltrating even tightly woven fabrics from penetrating the Environment Protection Garment (EPG) and compromising suit durability and astronaut safety. To enhance dust-blocking performance, the Artemis Suit Materials Team investigated calendaring, a continuous roll to roll mechanical finishing process in which fabric passes through heated rollers under high pressure to compress and flatten the weave, thereby reducing pore size and modifying surface texture without significantly affecting other properties. Targeted testing of calendared Teflon™ T-162 and Ortho Fabric samples provides new insight into how calendaring influences dust resistance, informing future material development and advancing EVA suit technology for long-duration lunar missions.

Dust↗
NASA NTRS2026

Artemis Suit Material Effects of Calendaring Woven Fabrics on Dust Resistance

This paper presents one element of an ongoing NASA technology-infusion effort to design, fabricate, and test a new outer shell fabric for a lunar Extravehicular Activity (EVA) space suit, a critical component of sustained lunar exploration. A primary challenge for suit textiles is preventing lunar dust, which is highly abrasive, electrostatically charged, and capable of infiltrating even tightly woven fabrics from penetrating the Environment Protection Garment (EPG) and compromising suit durability and astronaut safety. To enhance dust-blocking performance, the Artemis Suit Materials Team investigated calendaring, a continuous roll to roll mechanical finishing process in which fabric passes through heated rollers under high pressure to compress and flatten the weave, thereby reducing pore size and modifying surface texture without significantly affecting other properties. Targeted testing of calendared Teflon™ T-162 and Ortho Fabric samples provides new insight into how calendaring influences dust resistance, informing future material development and advancing EVA suit technology for long-duration lunar missions.

Dust↗
DOE OSTI2020

Assessing mechanical response of CO 2 storage into a depleted carbonate reef using a site-scale geomechanical model calibrated with field tests and InSAR monitoring data

Geomechanical risks of injection have raised concerns regarding secure CO 2 storage. In this work, a combined monitoring and modeling approach is used to assess the stress changes and surface uplift associated with CO 2 injection into a depleted carbonate reef of the Michigan basin. A site-scale geomechanical model is built by assigning mechanical properties of formations using well-log and experimental data. Gravity load is applied to the model to estimate the vertical component of stress as well as different lateral boundary displacement scenarios to estimate horizontal stresses. We used a poroelastic pressure-dependent model (instead of a linear elastic mechanical earth model) to calibrate initial stresses using hydraulic fracture test data measured at depleted reservoir status. Multi-phase fluid flow-geomechanical simulations are performed to estimate the poroelastic response during (1) primary depletion (2) field-scale CO 2 injection phase (3) a hypothetical forecast scenario in which well bottom hole pressure (BHP) reach 45000 KPa. The predicted surface uplift is less than 1 mm at the end of the field-scale CO 2 injection phase which is in good agreement with Interferometric Synthetic Aperture Radar (InSAR) uplift measurement. Although the InSAR data shows an insignificant uplift, hydromechanical modeling of injection shows that CO 2 injection still causes reservoir deformation emphasizing the role of carbonate overburden and reservoir formation mechanical properties and limited size of reef on diminishing the surface deformation. Modeling indicates poroelastic response of caprock matters to estimate uplift. The lower permeability of the top two layers provides additional barrier to large uplift. Also, history of subsidence due to production should be accounted to predict uplift due to a follow up injection correctly. This report shows the significance of combining a calibrated geomechanical model with field measured stresses and monitoring data to be used as a tool to ensure the safety of CO 2 storage.

42 ENGINEERING↗
DOE OSTI2024

Dynamic and quasi-static strength of additively repaired aluminum

Additive manufacturing has the potential to repair high value components, saving significant time and resources; however, the level of reliability and performance of additive repairs is still relatively unknown. In this work, the structure–property and performance of laser wire additive manufacturing repairs in 1100 aluminum are investigated. Two types of intentional damage are inflicted on the samples and subsequently repaired with pulsed laser deposition additive manufacturing. Quasi-static (10 –3 s –1 ) and high strain-rate (10 –3 s –1 ) mechanical testing is carried out with in situ diagnostics and post-mortem imaging. The results show that while the quasi-static strength and ductility of samples with a repaired region are lower than a pristine sample, the dynamic strength under shock loading is comparable. This work highlights both the potential utility of additive manufacturing for repair purposes, the significant risk of compromised performance of additive parts under specific conditions, and the need to test at varying strain rates to fully characterize material performance.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Anisotropy of nickel-base superalloy single crystals

The influence of orientation on the tensile and stress rupture behavior of 52 Mar-M247 single crystals was studied. Tensile tests were performed at temperatures between 23 and 1093 C; stress rupture behavior was examined between 760 and 1038 C. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factor contours for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The tensile properties correlated well with the appropriate Schmid factor contours. The stress rupture lives at lower testing temperatures were greatly influenced by the lattice rotations required to produce cross slip. A unified analysis was attained for the stress rupture life data generated for the Mar-M247 single crystals at 760 and 774 C under a stress of 724 MPa and the data reported for Mar-M200 single crystals tested at 760 C under a stress of 689 MPa. Based on this analysis, the stereographic triangle was divided into several regions which were rank ordered according to stress rupture life for this temperature regime.

Mackay, R. A.↗
NASA NTRS2005

RSRM TP-H1148 Main Grain Propellant Crack Initiation Evaluation

Pressurized TP-HI 148 propellant fracture toughness testing was performed to assess the potential for initiation of visually undetectable cracks in the RSRM forward segment transition region during motor ignition. Two separate test specimens were used in this evaluation. Testing was performed in cold-gas and hot-fire environments, and under both static and dynamic pressurization conditions. Analysis of test results demonstrates safety factors against initiation of visually undetectable cracks in excess of 8.0. The Reusable Solid Rocket Motor (RSRM) forward segment is cast with PBAN propellant (TP-HI 148) to form T an 1 1-point star configuration that transitions to a tapered center perforated bore (see Figure 1). The geometry of the transition region between the fin valleys and the bore causes a localized area of high strain during horizontal storage. Updated analyses using worst-case mechanical properties at 40 F and improved modeling techniques indicated a slight reduction in safety margins over previous predictions. Although there is no history of strain induced cracks or flaws in the transition region propellant, a proactive test effort was initiated to better understand the implications of the new analysis, primarily the resistance of TP-H1148 propellant to crack initiation' during RSRM ignition.

Earnest, Todd E.↗
NASA NTRS1980

Mechanisms of lubrication and wear of a bonded solid lubricant film

To obtain a better understanding of how bonded solid lubricant films lubricate and wear (in general), the tribological properties of polyimide-bonded graphite fluoride films were studied (in specific). A pin-on-disk type of testing apparatus was used; but in addition to sliding a hemispherically tipped rider, a rider with a 0.95 mm diameter flat area was slid against the film. This was done so that a lower, less variable contact stress could be achieved. Two stages of lubrication occurred. In the first, the film supported the load. The lubricating mechanism consisted of the shear of a thin surface layer (of the film) between the rider and the bulk of the film. The second occurred after the bonded film had worn to the substrate, and consisted of the shear of very thin lubricant films between the rider and flat plateaus generated on the metallic substrate asperities. The film wear mechanism was strongly dependent on contact stress.

Fusaro, R. L.↗
DOE OSTI2023

Experimental Simulations of Field-Induced Mechanical Abuse Conditions

Mechanical failure of cell components is an important component to understanding safety outcomes for batteries subjected to external loading. Several key parameters governing the mechanical response at the component to the module level are discussed in this chapter. Specifically, nuances associated with experimental measurements of these properties – including development of test methods, fixturing the test articles, ways to minimize errors in measurements, and improving the repeatability of some of these experiments – are examined closely.

Torres-castro, Loraine↗
NASA NTRS1976

Refinement of Promising Coating Compositions for Directionally Cast Eutectics

The successful application of high creep strength, directionally solidified gamma/gamma prime-delta (Ni-19.7Cb-6Cr-2.5Al) eutectic superalloy turbine blades requires the development of suitable coatings for airfoil, root and internal blade surfaces. In order to improve coatings for the gamma/gamma prime-delta alloy, the current investigation had the goals of (1) refining promising coating compositions for directionally solidified eutectics, (2) evaluating the effects of coating/ substrate interactions on the mechanical properties of the alloy, and (3) evaluating diffusion aluminide coatings for internal surfaces. Burner rig cyclic oxidation, furnace cyclic hot corrosion, ductility, and thermal fatigue tests indicated that NiCrAlY+Pt(63 to 127 micron Ni-18Cr-12Al-0.3Y + 6 micron Pt) and NiCrAlY(63 to 127 micron Ni-18Cr-12Al-0.3Y) coatings are capable of protecting high temperature gas path surfaces of eutectic alloy airfoils. Burner rig (Mach 0.37) testing indicated that the useful coating life of the 127 micron thick coatings exceeded 1000 hours at 1366 K (2000 deg F). Isothermal fatigue and furnance hot corrosion tests indicated that 63 micron NiCrAlY, NiCrAlY + Pt and platinum modified diffusion aluminide (Pt + Al) coating systems are capable of protecting the relatively cooler surfaces of the blade root. Finally, a gas phase coating process was evaluated for diffusion aluminizing internal surfaces and cooling holes of air-cooled gamma/gamma prime-delta turbine blades.

Strangman, T. E.↗
NASA NTRS1978

Development of advanced composite structures

Composite structure programs: the L-1011 Advanced Composite Vertical Fin (ACVF), the L-1011 Advanced Composite Aileron, and a wing study program were reviewed. These programs were structured to provide the technology and confidence for the use of advanced composite materials for primary and secondary structures of future transport aircraft. The current status of the programs is discussed. The results of coupon tests for both material systems are presented as well as the ACVF environmental (moisture and temperature) requirements. The effect of moisture and temperature on the mechanical properties of advanced composite materials is shown. The requirements set forth in the FAA Certification Guidelines for Civil Composite Aircraft Structures are discussed as they relate to the ACVF.

Stauffer, W. A.↗
NASA NTRS1982

Polymer research at NASA Langley Research Center

Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.

Terry L. St. Clair↗
NASA NTRS1985

An electrochemical study of the corrosion behavior of primer coated 2219-T87 aluminum

The corrosion behavior for 2219-T87 aluminum coated with various primers, including those used for the external tank and solid rocket boosters of the Space Shuttle Transportation System, were investigated using electrochemical techniques. Corrosion potential time, polarization resistance time, electrical resistance time, and corrosion rate time measurements were all investigated. It was found that electrical resistance time and corrosion rate time measurement were most useful for studying the corrosion behavior of painted aluminum. Electrical resistance time determination give useful information concerning the porosity of paint films, while corrosion rate time curves give important information concerning overall corrosion rates and corrosion mechanisms. In general, the corrosion rate time curves all exhibited at least one peak during the 30 day test period, which was attributed, according to the proposed mechanisms, to the onset of the hydrogen evolution reaction and the beginning of destruction of the protective properties of the paint film.

Danford, M. D.↗
NASA NTRS1985

Effects of real-time thermal aging on graphite/polyimide composites

As part of a program to evaluate high-temperature advanced composites for use on supersonic cruise transport aircraft, two graphite/polyimide composites have been aged at elevated temperatures for times up to 5.7 years. Work on the first, HT-S/710 graphite/polyimide, was started in 1974. Evaluation of the second polyimide, Celion 6000/LARC-160, began in 1980. Baseline properties are presented, including unnotched and notched tensile data as a function of temperature, compression, flexure, shear, and constant-amplitude fatigue data at R = 0.1 and R = -1. Tensile specimens were aged in ovens where pressure and aging temperatures were controlled for various times up to and including 50,000 hours. Changes in tensile strength were determined and plotted as a function of aging time. The HT-S/710 composite aged at 450 F and 550 F if compared to the Celion 6000/LARC-160 composite aged at 350 F and 450 F. After tensile testing, many of the thermal aging specimens were examined using a scanning electron microscope. Results of these studies are presented, and changes in properties and degradation mechanisms during high-temperature aging are discussed and illustrated using metallographic techniques.

Haskins, J. F.↗
NASA NTRS1985

Mechanical properties of Inconel 718 and Nickel 201 alloys after thermal histories simulating brazing and high temperature service

An experimental investigation was made to evaluate two nickel base alloys (Nickel-201 and Inconel-718) in three heat treated conditions. These conditions were: (1) annealed; (2) after thermal exposure simulating a braze cycle; and (3) after a thermal exposure simulating a braze cycle plus one operational lifetime of high temperature service. For the Nickel-201, two different braze cycle temperatures were evaluated. A braze cycle utilizing a lower braze temperature resulted in less grain growth for Nickel-201 than the standard braze cycle used for joining Nickel-201 to Inconel-718. It was determined, however, that Nickel-201, was marginal for temperatures investigated due to large grain growth. After the thermal exposures described above, the mechanical properties of Nickel-201 were degraded, whereas similar exposure on Inconel-718 actually strengthened the material compared with the annealed condition. The investigation included tensile tests at both room temperature and elevated temperatures, stress-rupture tests, and metallographic examination.

James, W. F.↗