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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Laboratory experiments from the toy store

The following is a laboratory experiment designed to further understanding of materials science. This material could be taught to a typical student of materials science or manufacturing at the high school level or above. The objectives of this experiment are as follows: (1) to qualitatively demonstrate the concepts of elasticity, plasticity, and the strain rate and temperature dependence of the mechanical properties of engineering materials; (2) to qualitatively demonstrate the basics of extrusion including material flow, strain rate dependence of defects, lubrication effects, and the making of hollow shapes by extrusion (the two parts may be two separate experiments done at different times when the respective subjects are covered); and (3) to demonstrate the importance of qualitative observations and the amount of information which can be gathered without quantitative measurements.

Mcclelland, H. T.↗
DOE OSTI2023

Bayesian optimization with active learning of design constraints using an entropy-based approach

Abstract The design of alloys for use in gas turbine engine blades is a complex task that involves balancing multiple objectives and constraints. Candidate alloys must be ductile at room temperature and retain their yield strength at high temperatures, as well as possess low density, high thermal conductivity, narrow solidification range, high solidus temperature, and a small linear thermal expansion coefficient. Traditional Integrated Computational Materials Engineering (ICME) methods are not sufficient for exploring combinatorially-vast alloy design spaces, optimizing for multiple objectives, nor ensuring that multiple constraints are met. In this work, we propose an approach for solving a constrained multi-objective materials design problem over a large composition space, specifically focusing on the Mo-Nb-Ti-V-W system as a representative Multi-Principal Element Alloy (MPEA) for potential use in next-generation gas turbine blades. Our approach is able to learn and adapt to unknown constraints in the design space, making decisions about the best course of action at each stage of the process. As a result, we identify 21 Pareto-optimal alloys that satisfy all constraints. Our proposed framework is significantly more efficient and faster than a brute force approach.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Phase transitions and octahedral rotations in epitaxial Ag(Ta x Nb 1-x )O 3 thin films under tensile strain

In this paper, epitaxial Ag(Ta 0.5 Nb 0.5 )O 3 (ATN) films under tensile strain were deposited on (Ba 0.4 Sr 0.6 )TiO 3 /LaAlO 3 (001) p and KTaO 3 (001) substrates. These films exhibited a domain structure with the c-axis aligned primarily along the in-plane direction in contrast with the poly-domain nature of bulk ATN ceramics or relaxed films. While the generic phase transition sequence of the tensile films was qualitatively similar to bulk, the tetragonal and orthorhombic phase field regions expanded by ~270 °C in ATN/(Ba 0.4 Sr 0.6 )TiO 3 /LaAlO 3 . Furthermore, the films were found to be in the M 3 (complex octahedral tilting with disordered Nb/Ta displacements) phase at room temperature with either significantly reduced tilt angles or a suppression of the long range order of the complex tilt as compared to bulk materials. It was observed that the octahedral tilt domains were oriented with the complex tilt axes lying in the plane of the film due to the tensile strain. Finally, this work demonstrates that tensile strain can be used to strain-engineer materials with complex tilt systems and thereby modify functional properties.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1990

The effect of thermal damage on the mechanical properties of polymer regrinds

Reprocessed polymers are subjected to high processing temperatures that result in the breakdown of molecular chains and changes in the molecular structures. These phenomena are reflected in the mechanical properties of materials. Practically every regrind is seen as a new material. These experiments deal with the molding, regrinding, and reprocessing of test specimens for the study of their mechanical properties. The comparative test data from each recycled material would give students an insight of the molecular structures and property degradation. Three important rheological and mechanical properties such as melt flow, impact strength, and flexural strength are to be determined. These properties play key roles in the selection of engineering materials. The material selected for demonstration was Makrolon 3000L, a polycarbonate thermoplastic from Bayer AG. The thermal degradation due to repeated processing is reflected in the decrease in molecular weight and breakdown of molecular chains causing increase in melt flow. The Izod-impact resistance and the flexural strength deteriorate gradually.

Kundu, Nikhil K.↗
NASA NTRS2003

Technical Education Outreach in Materials Science and Technology Based on NASA's Materials Research

The grant NAG-1 -2125, Technical Education Outreach in Materials Science and Technology, based on NASA s Materials Research, involves collaborative effort among the National Aeronautics and Space Administration s Langley Research Center (NASA-LaRC), Norfolk State University (NSU), national research centers, private industry, technical societies, colleges and universities. The collaboration aims to strengthen math, science and technology education by providing outreach related to materials science and technology (MST). The goal of the project is to transfer new developments from LaRC s Center for Excellence for Structures and Materials and other NASA materials research into technical education across the nation to provide educational outreach and strengthen technical education. To achieve this goal we are employing two main strategies: 1) development of the gateway website and 2) using the National Educators Workshop: Update in Engineering Materials, Science and Technology (NEW:Updates). We have also participated in a number of national projects, presented talks at technical meetings and published articles aimed at improving k-12 technical education. Through the three years of this project the NSU team developed the successful MST-Online site and continued to upgrade and update it as our limited resources permitted. Three annual NEW:Updates conducted from 2000 though 2002 overcame the challenges presented first by the September 11,2001 terrorist attacks and the slow U.S. economy and still managed to conduct very effective workshops and expand our outreach efforts. Plans began on NEW:Update 2003 to be hosted by NASA Langley as a part of the celebration of the Centennial of Controlled Flight.

Jacobs, James A.↗
NASA NTRS2020

Toward an In-Depth Material Model for Cermet Nuclear Thermal Rocket Fuel Elements

The development and qualification of nuclear thermal propulsion (NTP) fuel element technologies would be aided by an in-depth model of material response and failure modes at operating conditions. Integrated computational materials engineering techniques have the potential to provide such a model, as demonstrated here through three case studies focused on a tungsten-uranium mononitride cermet fuel. The first case focuses on the erosion of tungsten (W, also named wolfram), a nominal coating/cladding material, in hot hydrogen. Ab initio techniques are used to calculate erosion rates and thermal expansion at NTP operating conditions. The second focuses on the stability of uranium mononitride (UN) fuels at high temperature and in the presence of hydrogen. Phase diagram techniques reveal potential instabilities and decomposition pathways at high hydrogen concentrations. The third focuses on using microstructure information to predict high temperature mechanical response and failure of tungsten, used in refractory cermet materials. Combined finite element and discrete dislocation dynamics techniques provide mechanical properties in agreement with experimental methods. The integration of these techniques for an all-encompassing material model is discussed.

cermet↗
DOE OSTI2019

Focused-helium-ion-beam blow forming of nanostructures: radiation damage and nanofabrication

Targeted irradiation of nanostructures by a finely focused ion beam provides routes to improved control of material modification and understanding of the physics of interactions between ion beams and nanomaterials. Here, we studied radiation damage in crystalline diamond and silicon nanostructures using a focused helium ion beam, with the former exhibiting extremely long-range ion propagation and large plastic deformation in a process visibly analogous to blow forming. We report significant dependence of damage morphology on material, geometry, and irradiation conditions (ion dose, ion energy, ion species, and location). In this work, we suggest that our approach and findings will not only improve the understanding of radiation damage in isolated nanostructures, but will also support the design of new engineering materials and devices for current and future applications in nanotechnology.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS2003

High Altitude Launch for a Practical SSTO

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. High-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2% of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated into increased payload capability to orbit, ranging from 5 to 20% increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2% of gross lift-off weight, this corresponds to 31% increase in payload (for 5-km launch altitude) to 122% additional payload (for 25-km launch altitude).

Landis, Geoffrey A.↗
NASA NTRS2003

High Altitude Launch for a Practical SSTO

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. high-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2% of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated in to increased payload capability to orbit, ranging from 5 to 20% increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2% of gross lift-off weight, this corresponds to 31 % increase in payload (for 5-km launch altitude) to 122% additional payload (for 25-km launch altitude).

Landis, Geoffrey A.↗
NASA NTRS2003

High Altitude Launch for a Practical SSTO

Existing engineering materials allow the construction of towers to heights of many kilometers. Orbital launch from a high altitude has significant advantages over sea-level launch due to the reduced atmospheric pressure, resulting in lower atmospheric drag on the vehicle and allowing higher rocket engine performance. High-altitude launch sites are particularly advantageous for single-stage to orbit (SSTO) vehicles, where the payload is typically 2 percent of the initial launch mass. An earlier paper enumerated some of the advantages of high altitude launch of SSTO vehicles. In this paper, we calculate launch trajectories for a candidate SSTO vehicle, and calculate the advantage of launch at launch altitudes 5 to 25 kilometer altitudes above sea level. The performance increase can be directly translated into increased payload capability to orbit, ranging from 5 to 20 percent increase in the mass to orbit. For a candidate vehicle with an initial payload fraction of 2 percent of gross lift-off weight, this corresponds to 31 percent increase in payload (for 5-kilometer launch altitude) to 122 percent additional payload (for 25-kilometer launch altitude).

Landis, Geoffrey A.↗
NASA NTRS2004

History of Sulphur Content Effects on the Thermal Stability of RP-1 under Heated Conditions

As technologies advance in the aerospace industry, a strong desire has emerged to design more efficient, longer life, reusable liquid hydrocarbon fueled rocket engines. To achieve this goal, a more complete understanding of the thermal stability and chemical makeup of the hydrocarbon propellant is needed. Since the main fuel used in modern liquid hydrocarbon systems is RP-1, there is concern that Standard Grade RP-1 may not be a suitable propellant for future-generation rocket engines due to concern over the outdated Mil-Specification for the fuel. This current specification allows high valued limits on contaminants such as sulfur compounds, and also lacks specification of required thermal stability qualifications for the fuel. Previous studies have highlighted the detrimental effect of high levels of mercaptan sulfur content (^50 ppm) on copper rocket engine materials, but the fuel itself has not been studied. While the role of sulfur in other fuels (e.g., aviation, diesel, and automotive fuels) has been extensively studied, little has been reported on the effects of sulfur levels in rocket fuels. Lower RP-1 sulfur concentrations need to be evaluated and an acceptable sulfur limit established before RP-1 can be recommended for use as the propellant for future launch vehicles. (5 tables, 8 figures, 9 refs.)

ASTM METHOD D-5623↗
DOE OSTI2018

A thermal study of amorphous and textured carbon and carbon nitride thin films via transient grating spectroscopy

Here in this study, we are considering a novel way of growing carbon nitride (CN) films by using High Power Impulse Magnetron Sputtering (HiPIMS). Carbon and CN thin films were grown on silicon substrate with varying nanocrystalline texturing: some samples were amorphous while others were either nanocrystalline graphite (for the carbon sample) or fullerene-like (for the CN sample), with both samples having a graphitic nanostructure vertically ordered throughout the film. Their thermal diffusivity was computed using transient grating spectroscopy in order to compare the impact of the material's nanostructure on its thermal property as well as benchmarking the performance of CN. It was found that the thermal properties of carbon thin films were decreased when doped with nitrogen, which is attributed to the increased atomic disorder introduced by the nitrogen cross-linking, impacting the phonon propagation. The impact of nitrogen doping on thermal properties opens new avenues in engineering materials with tailored and varying thermal properties at the microscale.

42 ENGINEERING↗
DOE OSTI2022

Terahertz Circular Dichroism Spectroscopy of Molecular Assemblies and Nanostructures

Chemical, physical, biological and materials engineering disciplines use a variety of chiroptical spectroscopies to probe geometrical and optical asymmetry in molecules and particles. Electronic (ECD) and vibrational (VCD) circular dichroism are the most common of these techniques and collectively enable the studies of electronic and vibronic transitions with energies between 0.1 and 5.0 eV. The vibrational states with characteristic energies in the range of 0.001–0.01 eV carry valuable information about concerted intermolecular motions in molecules and crystals involving multiple atoms. These vibronic transitions located in the terahertz (THz) part of the spectrum become increasingly more important for the chemistry, physics, and biology of complex molecules and materials However, the methodology and hardware of THz circular dichroism (TCD) are much less developed than the chiroptical spectroscopies for ultraviolet, visible, near- and mid infrared photons. In this report we provide theoretical foundations, practical implementations, comparative assessments, and exemplary applications of TCD spectroscopy. We show that the sign, intensity, and position of TCD peaks are highly sensitive to the three-dimensional structure and long-range organization of molecular crystals, which offer unique capabilities to study (bio) molecules, their crystals, and nanoscale assemblies and apply the novel data processing methodologies. TCD also offers a convenient toolbox to identify new physical phenomena, such as chiral phonons and their propagation in nanostructured matter. We also discuss the major challenges, emerging opportunities and promising research directions, including broad investigation of chiral phonons observed in chiral (nano) crystals and emerging machine learning methodologies for TCD in biological and nanoscale structures. Ubiquity of low-frequency vibrations with rotational components in biomolecular structures, combined with sharpness of peaks in TCD spectra, enables a variety of technological translations.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Shift current bulk photovoltaic effect in polar materials—hybrid and oxide perovskites and beyond

Here, the bulk photovoltaic effect (BPVE) refers to the generation of a steady photocurrent and above-bandgap photovoltage in a single-phase homogeneous material lacking inversion symmetry. The mechanism of BPVE is decidedly different from the typical p–n junction-based photovoltaic mechanism in heterogeneous materials. Recently, there has been renewed interest in ferroelectric materials for solar energy conversion, inspired by the discovery of above-bandgap photovoltages in ferroelectrics, the invention of low bandgap ferroelectric materials and the rapidly improving power conversion efficiency of metal halide perovskites. However, as long as the nature of the BPVE and its dependence on composition and structure remain poorly understood, materials engineering and the realisation of its true potential will be hampered. In this review article, we survey the history, development and recent progress in understanding the mechanisms of BPVE, with a focus on the shift current mechanism, an intrinsic BPVE that is universal to all materials lacking inversion symmetry. In addition to explaining the theory of shift current, materials design opportunities and challenges will be discussed for future applications of the BPVE.

36 MATERIALS SCIENCE↗
NASA NTRS1979

Conference on Fire Resistant Materials: A compilation of presentations and papers

The proceedings of the NASA IRE Resistant Materials Engineering (FIREMEN) Program held at Boeing Commercial Airplane Company, Seattle, Washington, on March 1-2, 1979 are reported. The conference was to discuss the results of research by the National Aeronautics and Space Administration in the field of aircraft fire safety and fire-resistant materials. The program topics include the following: (1) large-scale testing; (2) fire toxicology; (3) polymeric materials; and (4) fire modeling.

Kourtides, D. A.↗
NASA NTRS1979

Release adiabat measurements on minerals - The effect of viscosity

The paper examines the effect of viscosity in the release adiabat measurements on minerals. The current inversion of pressure-particle velocity data for release from a high-pressure shock state to a pressure-density path usually depends critically upon the assumption that the release process is isentropic. It has been shown that the effective viscosity for geological materials below stresses of 150 GPa must be at least 1000 kg/m/s so that viscous work in the shock state remains small compared to mechanical work recovered upon adiabatic rarefaction. The magnitude of the shear stress in the shock state in minerals and viscosities of engineering materials shocked to pressures below 150 GPa show effective viscosities of about 1000 kg/m/s or less indicating that the conditions for isentropic release of materials from shock states are achieved and that the Riemann integral can be applied to obtain pressure-density states along the release adiabats of minerals.

Jeanloz, R.↗
NASA NTRS1990

NASA's HITEMP program for UHBR engines

NASA's High Temperature Engine Materials Program (HITEMP) is concerned with the laboratory-scale technology development and feasibility demonstration of high-temperature composite materials, in conjunction with the requisite structural analysis models and test methods for their validation. HITEMP encompasses research on metallic/intermetallic, ceramic, and polymer matrix composites, and is giving attention to high-temperature component composites applicable to future widebody commercial aircraft ultrahigh bypass ratio (UHBR) engines. The UHBR components for which advanced composites are envisioned are fan, compressor, and turbine rotor blades, stator vanes, disks, and shafts, thrust bearings, gearbox bearings and linings, combustor cases and linings, nacelles, and thrust-reversers.

Stephens, Joseph R.↗
NASA NTRS1997

Micromechanical Modeling Efforts for Advanced Composites

Over the past two decades, NASA Lewis Research Center's in-house efforts in analytical modeling for advanced composites have yielded several computational predictive tools. These are, in general, based on simplified micromechanics equations. During the last 3 years, our efforts have been directed primarily toward developing prediction tools for high temperature ceramic matrix composite (CMC's) materials. These materials are being considered for High Speed Research program applications, specifically for combustor liners. In comparison to conventional materials, CMC's offer several advantages: high specific stiffness and strength, and higher toughness and nonbrittle failure in comparison to monolithic ceramics, as well as environmental stability and wear resistance for both roomtemperature and elevated-temperature applications. Under the sponsorship of the High Temperature Engine Materials Program (HITEMP), CMC analytical modeling has resulted in the computational tool Ceramic Matrix Composites Analyzer (CEMCAN).

Source record↗