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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Mechanics Methodology for Textile Preform Composite Materials

NASA and its contractors have completed a program to develop a basic mechanics underpinning for textile composites. Three major deliverables were produced by the program: 1. A set of test methods for measuring material properties and design allowables; 2. Mechanics models to predict the effects of the fiber preform architecture and constituent properties on engineering moduli, strength, damage resistance, and fatigue life; and 3. An electronic data base of coupon type test data. This report describes these three deliverables.

Poe, Clarence C., Jr.↗
NASA NTRS1974

Mechanical properties of Skylab thermal shield materials after prolonged ultraviolet irradiation

In response to an emergency request, the mechanical properties of two complex laminate materials, used as thermal shields on the Skylab spacecraft, were investigated. Concern over the prolonged use of these materials in the space environment prompted this investigation. Shields made of both of these materials, popularly called the parasol and the sail types, were taken to the Skylab spacecraft by the original Skylab astronauts. Both were used to restore thermal control after the original control surfaces were damaged during launch. During the tests the tensile properties were measured at anticipated service temperature and after prolonged exposure to increasing degrees of ultraviolet radiation at intensities approaching two solar constants. Some samples received exposures equivalent to 2,350 hours. The performance and degradation of the two materials are presented in terms of orientation, vacuum, and degree of irradiation. In general, the 75-micron (3-mil) parasol laminate showed a decrease in tensile properties as a function of exposure time, while the 200-micron (8-mil) sail laminate was little affected by exposure to the ultraviolet radiation.

Haehner, C. L.↗
DOE OSTI2024

Multi-principal element alloys for fast reactor cladding applications

Given the extensive list of multi-principal element alloys (MPEAs) within literature and the overwhelming number of alloys that can be made from only a handful of elements, this article proposes a methodology for prioritizing alloys for use as cladding within advanced reactors. This paper applies neutronic, mechanical, and chemical assessments to a collection of MPEAs available within literature for use as advanced reactor cladding. The results are compared to a reference design of HT9, a ferritic/martensitic steel, for employed in sodium-cooled fast reactor. Mechanical assessments determined pressure limits for a thin-walled tube pressure boundary, thus relating the material's mechanical properties to a minimum acceptable wall thickness. Neutronic analyses reveal a maximum allowable wall thickness that a given material must meet to provide a level of neutronic economy that is equivalent to than that of HT9. Lastly, each alloying element is compared to typical fission products found in a fast reactor fuels to mitigate deleterious phenomena such as fuel-cladding chemical interactions (FCCI). These analyses indicate that Mo-Nb-Ti-V-based alloys are likely to be advantageous and that the inclusion of elements with a high neutronic penalty (e.g., Hf) could be considered with minimal consequences.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Prediction of Probabilistic Shock Initiation Thresholds of Energetic Materials Through Evolution of Thermal-Mechanical Dissipation and Reactive Heating

The ignition threshold of an energetic material (EM) quantifies the macroscopic conditions for the onset of self-sustaining chemical reactions. The threshold is an important theoretical and practical measure of material attributes that relate to safety and reliability. Historically, the thresholds are measured experimentally. In this work, we present a new Lagrangian computational framework for establishing the probabilistic ignition thresholds of heterogeneous EM out of the evolutions of coupled mechanical-thermal-chemical processes using mesoscale simulations. Furthermore, the simulations explicitly account for microstructural heterogeneities, constituent properties, and interfacial processes and capture processes responsible for the development of material damage and the formation of hotspots in which chemical reactions initiate. The specific mechanisms tracked include viscoelasticity, viscoplasticity, fracture, post-fracture contact, frictional heating, heat conduction, reactive chemical heating, gaseous product generation, and convective heat transfer. To determine the ignition threshold, the minimum macroscopic loading required to achieve self-sustaining chemical reactions with a rate of reactive heat generation exceeding the rate of heat loss due to conduction and other dissipative mechanisms is determined. Probabilistic quantification of the processes and the thresholds are obtained via the use of statistically equivalent microstructure sample sets (SEMSS). The predictions are in agreement with available experimental data.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Wrinkle ridge-upland scarp transitions: Implications for the mechanical properties of the deformed materials

Wrinkle ridge-upland scarp transitions are structures that occur at the contact between smooth plains material and highlands or uplands materials on the Moon and Mars. In the smooth plains material the structures have a morphology typical of wrinkle ridges, interpreted to be the result of a combination of folding and thrust faulting. Where the structures extend into the uplands, a distinct change in the morphology occurs. The generally asymmetric cross sectional geometry characteristics of wrinkle ridges becomes that of a one-sided, often lobate scarp. The scarp is indistinguishable from other highland/upland scarps, interpreted to be the result of reverse or thrust faulting. Although these structures are rare, they provide important insight into the mechanical properties of deformed materials. These insights are discussed.

Watters, Thomas R.↗
NASA NTRSDate not supplied

Nb-1Zr L-PBF In-situ Alloying and Elevated Temperature Mechanical Performance

Nb-1Zr is a readily-fabricable, dispersion-strengthened niobium alloy with improved elevated temperature properties compared to commercially pure niobium. This moderate strength niobium alloy is desirable in thermal management systems for fission power and propulsion applications; however, pre-alloyed spherical feedstock is generally unavailable. Laser powder bed fusion (L-PBF) in-situ alloying of a Nb-1Zr chemistry was performed using a pure niobium feedstock coated with 1 wt% of zirconium-based ceramic compound nano-powders. The additively manufactured material was mechanically tested at elevated temperatures in a controlled environment in the as-built condition. For comparison, traditionally manufactured wrought feedstock was also tested under identical conditions. Examination of the materials’ microstructure and elevated temperature mechanical response aimed to determine the Zr-compound nano-powder addition with the best performance, and the overall feasibility of the in-situ alloying approach.

Niobium-based alloys↗
DOE OSTI2022

Novel processing route for design and manufacturing of metal toughened nanoceramics: Al–Al 2 O 3 nanocermets

Monolithic alumina is a highly brittle ceramic with a very low fracture toughness, making it an unreliable material for mechanical and structural applications. Ceramic-metal composites (cermets) are the subject of intensive interest to obtain materials which can address the intrinsic brittleness of ceramics without compromising their high strength and light weight. In the present investigation, aluminium-alumina (Al–Al 2 O 3 ) nanocermets were developed. The nanocermets possessed the toughness of Al phase and the strength of reinforced nano Al 2 O 3 particles. Here, the nanocermets green bodies were prepared such that upon sintering each adjacent Al 2 O 3 grain was conformally coated with a continuous Al film. Mechanical milling via a combination of cryo-milling and ball-milling was used to prepare Al–Al 2 O 3 nano-powder mixture. Spark plasma sintering was used to consolidate the green nanocermets. Results show that specimens prepared from 35 h milled powders exhibited superior mechanical properties as compared to other nanocermets, with an improvement in microhardness, elastic modulus, compressive strength, and flexural strength by 88%, 78%, 69% and 40% with respect to sintered pure Al. The indentation toughness of 35 h milled nanocermet showed an increment of 12.5% with respect to sintered pure Al 2 O 3 . Characterization techniques such as XRD, SEM, HR-TEM, X-ray tomography were employed to investigate the phase evolution and structural morphology, while FEM simulations were performed for understanding the crack propagation mechanisms in nanocermets.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fatigue Performance of an Improved Creep Strength 10%Cr Steel

The deployment of 9-12% Cr steels for elevated temperature applications up to 650 °C presents a cost-effective alternative to more expensive nickel-based alloys in steam turbine power generation. To enhance creep resistance at this temperature range, a novel ferritic-martensitic steel, designated CPJ7, was developed and fabricated at the National Energy Technology Laboratory. The alloy design aimed to mitigate the transformation of strengthening carbides into deleterious phases that degrade creep performance. Results have demonstrated that CPJ7 exhibits favorable creep and oxidation resistance at 650 °C. However, its fatigue performance remains unexplored. This study builds upon prior research by evaluating the low cycle fatigue behavior of CPJ7 and verifying that modifications beneficial to creep performance were not detrimental to the fatigue performance. The alloy was tested at both 650 °C and ambient temperature under fully reversed bending conditions (R = − 1) and a load ratio of 0.05. Furthermore, the alloy exhibits cyclic softening, a behavior consistent with other 9-10 wt.% Cr steels. Analysis of the microstructure and hysteresis loops further corroborate cyclic softening mechanisms typical of ferritic-martensitic steels. Overall, the fatigue performance of CPJ7 meets or exceeds that of P91 steel, demonstrating its potential for high-temperature structural applications.

9% Cr ferritic-martensitic steel↗
DOE OSTI2023

Unraveling kinking: A plasticity enhancing failure mode in high strength nano metallic laminates

Kinking is an important and plasticity-enhancing deformation/failure mode in numerous mechanically anisotropic materials including high-strength nano metallic laminates (NMLs). However, our current limited understanding of the mechanics of kinking and its dependence on microstructural attributes is insufficient for thoroughly comprehending and eventually being able to control failure behaviors of materials. In this study, we investigate kinking dependencies on microstructural attributes in NMLs via in situ micropillar compression, multiscale microstructure characterization, dislocation dynamic simulations, and crystal plasticity modeling. Additionally, by examining several NML systems (Cu/Fe, Ag/Fe, Al-4Mg/Fe), we demonstrate that the development of internal stresses during loading activates local layer-parallel glide triggering kinking in NMLs. Furthermore, this work reveals the effect of key microstructural features including layer thickness, layer waviness, interface barrier strength, and work hardening capacity on kink band formation in NMLs. More broadly, our efforts represent a generically applicable approach for probing large-strain deformation behavior of complex materials via synergetic modeling and experimental efforts.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Superconductinglike response in a driven gapped bosonic system

In this study, we propose a mechanism for the photoinduced superconductinglike response recently reported in cuprates and other strongly correlated materials. This mechanism relies on quantum-fluctuating bosons consisting of electron pairs. With periodic drive, the electron pairs and vacancies of pairs form a coherent nonequilibrium condensate, different from conventional superconductors, yet showing a superconductinglike response in some regime even with dissipation. Unlike the case of driven fermionic bands, which results in the familiar Floquet bands with hybridization gaps, for driven bosons the “gap” opens up in the momentum direction, resulting in a resonant region in momentum space where the eigenvalues are complex. We give a simple physical argument for why this picture leads to a “perfect conductor” which exhibits superconductinglike frequency-dependent conductivity but no Meissner response. While our model is quite general, in the case of cuprates, a quantum-fluctuating pair density wave in the pseudogap region may serve as the origin of the quantum-fluctuating electron pairs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1991

NASA-UVa light aerospace alloy and structures technology program

The general objective of the NASA-UVa Light Aerospace Alloy and Structures Technology Program was to conduct research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. The following research areas were actively investigated: (1) mechanical and environmental degradation mechanisms in advanced light metals and composites; (2) aerospace materials science; (3) mechanics of materials and composites for aerospace structures; and (4) thermal gradient structures.

Gangloff, Richard P.↗
NASA NTRS2006

Thermal Expansion of Three Closed Cell Polymeric Foams at Cryogenic Temperatures

The Space Shuttle External Tank (ET) contains the liquid H2 fuel and liquid oxygen oxidizer and supplies them under pressure to the three space shuttle main engines (SSME) in the orbiter during lift-off and ascent. The ET thermal protection system consists of sprayed-on foam insulation and pre-molded ablator materials. The closed-cell foams are the external coating on the ET and are responsible for minimizing the amount of moisture that condenses out and freezes on the tank from the humid air in Florida while it is on the pad with cryogenic propellant awaiting launch. This effort was part of the overall drive to understand the behavior of these materials under use-conditions. There are four specially-engineered closed-cell foams used on the tank. The thermal expansion (contraction) of three of the polyurethane and polyisocyanurate foams were measured from -423 F (the temperature of liquid hydrogen) to 125 F under atmospheric conditions and under vacuum. One of them, NCFI 24-124, is a mechanically-applied material and covers the main acreage of the tank, accounting for 77 percent of the total foam used. Another, BX-265, is also a mechanically-applied and hand-sprayed material used on the tank's "closeout" areas. PDL 1034 is a hand-poured foam used for filling odd-shaped cavities in the tank, Measurements were made in triplicate in the three primary material directions in the case of the first two materials and the two primary material directions in the case of the last. Task 1 was developing the techniques for getting a uniform heating rate and minimizing axial and radial thermal gradients in the specimens. Temperature measurements were made at four locations in the specimens during this initial development phase of testing. Major challenges that were overcome include developing techniques for transferring the coolant, liquid helium (-452 F), from its storage container to the test facility with a minimal transfer of heat to the coolant and control of the heating rate at the lowest temperatures.

Stokes, Eric↗
NASA NTRSDate not supplied

Evidence of High-Angle Ejecta from Impacts Iinto Various Granular Materials

The dominant mechanism for resurfacing airless bodies is the excavation and ejection of material during the formation of impact craters. Ejecta that is deposited proximal to the rim of craters formed in the gravity-regime (where gravitational forces are greater than material strength) form a relatively smooth and continuous deposit. Aside from far-field secondary craters, craters observed on continuous ejecta deposits are mostly assumed to be representative of the primary impactor flux after the time of deposition. Sustained primary bombardment should produce a homogeneous crater population across this surface, thus providing an opportunity to determine crater size-frequency distributions and surface chronologies. Deviations from this ideal have been observed as different crater-size distributions appearing between the continuous deposits and their superimposed melt ponds. Numerous explanations for this discrepancy have been proposed, one of which is the occurrence of self-secondary craters, which would be created by ejecta launched at sufficiently high-angles to re-impact the fresh continuous ejecta deposits. Here, we present results from cratering experiments to explore the influence of density, porosity, and friction on ejecta kinematics and report on the observation of such high-angle ejecta in cohesionless granular targets.

Impact crater↗
NASA NTRS1988

Prediction of high temperature metal matrix composite ply properties

The application of the finite element method (superelement technique) in conjunction with basic concepts from mechanics of materials theory is demonstrated to predict the thermomechanical behavior of high temperature metal matrix composites (HTMMC). The simulated behavior is used as a basis to establish characteristic properties of a unidirectional composite idealized an as equivalent homogeneous material. The ply properties predicted include: thermal properties (thermal conductivities and thermal expansion coefficients) and mechanical properties (moduli and Poisson's ratio). These properties are compared with those predicted by a simplified, analytical composite micromechanics model. The predictive capabilities of the finite element method and the simplified model are illustrated through the simulation of the thermomechanical behavior of a P100-graphite/copper unidirectional composite at room temperature and near matrix melting temperature. The advantage of the finite element analysis approach is its ability to more precisely represent the composite local geometry and hence capture the subtle effects that are dependent on this. The closed form micromechanics model does a good job at representing the average behavior of the constituents to predict composite behavior.

Caruso, J. J.↗
NASA NTRS2011

Materials Science Research Rack Onboard the International Space Station

The Materials Science Research Rack (MSRR) allows for the study of a variety of materials including metals, ceramics, semiconductor crystals, and glasses onboard the International Space Station (ISS). MSRR was launched on STS-128 in August 2009, and is currently installed in the U. S. Destiny Laboratory Module. Since that time, MSRR has performed virtually flawlessly logging more than 550 hours of operating time. Materials science is an integral part of development of new materials for everyday life here on Earth. The goal of studying materials processing in space is to develop a better understanding of the chemical and physical mechanisms involved. Materials science research benefits from the microgravity environment of space, where the researcher can better isolate chemical and thermal properties of materials from the effects of gravity. With this knowledge, reliable predictions can be made about the conditions required on Earth to achieve improved materials. MSRR is a highly automated facility containing two furnace inserts in which Sample Cartridge Assemblies (SCAs), each containing one material sample, can be processed up to temperatures of 1400C. Once an SCA is installed by a Crew Member, the experiment can be run by automatic command or science conducted via telemetry commands from the ground. Initially, 12 SCAs were processed in the first furnace insert for a team of European and US investigators. The processed samples have been returned to Earth for evaluation and comparison of their properties to samples similarly processed on the ground. A preliminary examination of the samples indicates that the majority of the desired science objectives have been successfully met leading to significant improvements in the understanding of alloy solidification processes. The second furnace insert will be installed in the facility in January 2011 for processing the remaining SCA currently on orbit. Six SCAs are planned for launch summer 2011, and additional batches are planned for future processing. This facility is available to support additional materials science investigations through programs such as the US National Laboratory, Technology Development, NASA Research Announcements, ESA application oriented research programs, and others. The development of the research rack was a cooperative effort between NASA's Marshall Space Flight Center and the European Space Agency (ESA).

Frazier, Natalie C.↗
DOE OSTI2019

Perovskite magnet with quantum mechanical glassiness

Magnetic materials of strongly correlated origin are at the forefront of research in the exploration of new quantum mechanical properties involving spin and charges. Quantum magnetic material with certain intrinsic functionalities, such as continuously fluctuating spins to the lowest accessible temperature - reminiscing a liquid pattern, is argued to form a new phase of matter. Envisaging a phenomenon where the continuously fluctuating spins are also randomly frozen in space, can diminish the distinction between the two opposite extremes of quantum and classical magnetism. Here, we report new evidence in this regard where the coexistence of quantum spin continuum with a spin glass order in Co-doped CaRuO3 perovskite is demonstrated. In experimental investigations of Co-doped CaRuO3 perovskite, we find that (a) a continuum spectrum in the energy-momentum space, due to the uncorrelated spin fluctuations, persists across the weak spin glass transition at T G ≃ 23 K and (b) the quantum fluctuation of magnetic moment is spatially confined to individual sites only, thereby making it an extremely local event. Thus, the fluctuating spins, at a given time, are also randomly frozen macroscopically. The experimental observations suggest the discovery of a new magnetic phase at the cross-road of classical and quantum physics in strongly correlated perovskite materials.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Simulating Meteor Ablation at the Hypersonic Materials Environmental Test System

The ablation mechanisms of stony meteorite material and a terrestrial analog were investigated at the Hypersonic Materials Environmental Test System (HyMETS) facility at NASA’s Langley Research Center. The primary analyte (Tamdakht-H5) and arc-jet test conditions were chosen to simulate the entry of an ordinary chondrite through the Earth’s mesosphere. Basalt was selected to compare the meteorite response against material with enhanced polymerization and an elevated concentration of volatile species. The initial ablation process for each material commences with the vaporization of volatile species and germination of a viscous melt layer on the stagnation surface. However, each material exhibited distinct mass loss mechanisms, with basalt recessing at twice the rate of Tamdakht. Inspection of high-speed video and chemical analysis of the post-test melt layer suggests the dominant mode of mass loss of Tamdakht is expressed through the vaporization of volatile compounds. Vaporization rates of Tamdakht are 18x higher than basalt under the most severe test conditions which provides enhanced thermal shielding. Furthermore, Tamdakht produces a relatively stable melt flow, as evidenced by perpetual growth at the sidewall and the exiguous detachment of molten material into the flow. The ablation mechanism of basalt is markedly different from Tamdakht and is governed by volatile species in the virgin material. The dominant mode of mass loss for basalt is attributed to the detachment of large sections of the stagnation surface near the edge radius. An additional but subordinate mode of mass loss is assigned to the removal of melt flow as it passes over the edge radius, where shear forces overcome the rheological properties of the molten matter. Finally, mechanistic details will be discussed in terms of designing future test campaigns, developing meteorite-based materials response models, and impacting the broader scope of the Asteroid Threat Assessment Project (ATAP).

Meteor Ablation↗