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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 1,747 records · Page 97
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Practical guide to understanding goodness-of-fit metrics used in chemical state modeling of x-ray photoelectron spectroscopy data by synthetic line shapes using nylon as an example

Chemical state analysis of a sample surface through fitting bell-shaped curves to x-ray photoelectron spectroscopic polymer data is reviewed using nylon to introduce and discuss aspects of data analysis. Different strategies for modeling chemistry in nylon spectra are presented and in so doing, a case is made to include in published science the design logic and implementation in terms of line shapes and optimization parameter constraints between components in a peak model. Imperfections in line shape relative to the true shape for photoemission lines, when compensated for using constraints to optimization parameters, are shown to provide chemical state information about a sample that justify, for peak models constructed with these limitations, metrics for goodness-of-fit different from those expected for pulse-counted data.

Materials Science↗
NASA NTRS1987

A unique measurement technique to study laminar-separation bubble characteristics on an airfoil

A 'nonintrusive', multielement heat-transfer sensor was designed to study laminar-separation bubble characteristics on a NASA LRN (1)-1010 low-Reynolds number airfoil. The sensor consists of 30 individual nickel films, vacuum-deposited on a thin substrate (0.05 mm) that was bonded to the airfoil model with the sensor array placed streamwise on the airfoil upper surface. Experiments were conducted on a 15-cm chord model in the 50,000-300,000 chord Reynolds number range. Time history as well as spectral analysis of signals from surface film gauges were simultaneously obtained to determine the location of laminar separation and the subsequent behavior of the separated shear layer. In addition to the successful determination of laminar separation, a new phenomenon involving a large phase shift in dynamic shear stresses across the separation and reattachment points was observed.

Stack, J. P.↗
NASA NTRS1998

Application of the ENS3DAE Euler/Navier-Stokes Aeroelastic method

This paper discusses recent applications of the ENS3DAE computational aeroelasticity method. In particular, it describes aeroelastic and unsteady aerodynamics calculations performed on wings with trailing edge control surfaces. These simulations include the investigation of control reversal for a structurally flexible wing with a deflected control surface, and a static and dynamic analysis of a rigid wing with an oscillating control surface. The two sets of calculations were performed independently on different wings using different grid topologies. The control reversal simulation represents an inviscid Euler static aeroelastic analysis of a thin wing with a rectangular planform. The geometry of this wing makes it suitable for computations using more approximate, inviscid aerodynamics methods. Thus, the results of the present Euler computations are compared with numerical data generated by a validated computational aeroelasticity code which uses a simpler aerodynamic formulation. The second illustrated case involves the simulation of a significantly more complex flowfield and the static and dynamic analyses of this geometry were performed using the viscous Navier-Stokes equation option in ENS3DAE. Results of both the steady and unsteady calculations on this wing are compared with existing experimental data.

Schuster, David M.↗
NASA NTRS1990

Are bars essential for starbursts in non-interacting galaxies

Analyzed here are the 1.6 and 2.2 micron images of a sample of galaxies that are classified as unbarred by the Revised Shapley-Ames Catalog. These galaxies have characteristic properties of nuclear starbursts and are examined through near infrared imaging in a search for hidden bars. Researchers selected a sample of 36 galaxies from the Revised Shapley-Ames Catalog that have far infrared luminosities greater than 10(exp 10) solar luminosity and hot Infrared Astronomy Satellite (IRAS) colors between 60 and 100 microns, indicative of nuclear starbursts, but are not classified as Seyfert 1 or 2. Their determination of the presence of a bar relies primarily on an analysis of the 2 micron image using the Galaxy Surface Photometry (GASP) package (Cawson, 1983). The GASP analysis programs determine the galaxy surface brightness and ellipticity profiles as well as the position angle and the center coordinates of the ellipses. To test the way that GASP will characterize the surface brightness of barred galaxies, two galaxies with known bars, NGC 1068 and NGC 2523, were imaged with the 2 micron camera and analyzed with GASP. Fifteen of the sample that are not clearly barred from optical data and are isolated were imaged at 1.6 and 2.2 microns; 9 of these do not appear to have bars. Strong bars therefore do not appear to be an absolute requirement for high infrared luminosity in isolated galaxies.

Pompea, Stephen M.↗
NASA NTRS1975

LANDSAT inventory of surface-mined areas using extendible digital techniques

Multispectral analysis of LANDSAT imagery provides a rapid and accurate means of identification, classification, and measurement of strip-mined surfaces in Western Maryland. Four band analysis allows distinction of a variety of strip-mine associated classes, but has limited extendibility. A method for surface area measurement of strip mines, which is both geographically and temporally extendible, was developed using band-ratioed LANDSAT reflectance data. The accuracy of area measurement by this method, averaged over three LANDSAT scenes taken between September 1972 and July 1974, is greater than 93%. Total affected acreage of large (50 hectare/120 acre) mines can be measured to within 1.0%.

Anderson, A. T.↗
NASA NTRS1992

A Combined XRD/XRF Instrument for Lunar Resource Assessment

Robotic surface missions to the Moon should be capable of measuring mineral as well as chemical abundances in regolith samples. Although much is already known about the lunar regolith, our data are far from comprehensive. Most of the regolith samples returned to Earth for analysis had lost the upper surface, or it was intermixed with deeper regolith. This upper surface is the part of the regolith most recently exposed to the solar wind; as such it will be important to resource assessment. In addition, it may be far easier to mine and process the uppermost few centimeters of regolith over a broad area than to engage in deep excavation of a smaller area. The most direct means of analyzing the regolith surface will be by studies in situ. In addition, the analysis of the impact-origin regolith surfaces, the Fe-rich glasses of mare pyroclastic deposits, are of resource interest, but are inadequately known; none of the extensive surface-exposed pyroclastic deposits of the Moon have been systematically sampled, although we know something about such deposits from the Apollo 17 site. Because of the potential importance of pyroclastic deposits, methods to quantify glass as well as mineral abundances will be important to resource evaluation. Combined x ray diffraction (XRD) and x ray fluorescence (XRF) analysis will address many resource characterization problems on the Moon. XRF methods are valuable for obtaining full major-element abundances with high precision. Such data, collected in parallel with quantitative mineralogy, permit unambiguous determination of both mineral and chemical abundances where concentrations are high enough to be of resource grade. Collection of both XRD and XRF data from a single sample provides simultaneous chemical and mineralogic information. These data can be used to correlate quantitative chemistry and mineralogy as a set of simultaneous linear equations, the solution of which can lead to full characterization of the sample. The use of Rietveld methods for XRD data analysis can provide a powerful tool for quantitative mineralogy and for obtaining crystallographic data on complex minerals.

Vaniman, D. T.↗
DOE OSTI2024

Surface Finishing and Coating Parameters Impact on Additively Manufactured Binder-Jetted Steel–Bronze Composites

In this paper, electroless nickel plating is explored for the protection of binder-jetting-based additively manufactured (AM) composite materials. Electroless nickel plating was attempted on binder-jetted composites composed of stainless steel and bronze, resulting in differences in the physicochemical properties. We investigated the impact of surface finishing, plating solution chemistry, and plating parameters to attain a wide range of surface morphologies and roughness levels. We employed the Keyence microscope to quantitatively evaluate dramatically different surface properties before and after the coating of AM composites. Scanning electron microscopy revealed a wide range of microstructural properties in relation to each combination of surface finishing and coating parameters. We studied chempolishing, plasma cleaning, and organic cleaning as the surface preparation methods prior to coating. We found that surface preparation dictated the surface roughness. Taguchi statistical analysis was performed to investigate the relative strength of experimental factors and interconnectedness among process parameters to attain optimum coating qualities. The quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the roughness of the nickel-plated surface were 17.95%, 8.2%, 50.02%, and 13.21%, respectively. On the other hand, the quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the thickness of nickel plating were 35.12%, 41.40%, 3.87%, and 18.24%, respectively. The optimum combination of the factors’ level projected the lowest roughness of Ra at 7.76 µm. The optimum combination of the factors’ level projected the maximum achievable thickness of ~149 µm. This paper provides insights into coating process for overcoming the sensitivity of AM composites in hazardous application spaces via robust coating.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Experimental assessment of a computer program used in Space Shuttle orbiter entry heating analysis

A high temperature reusable surface insulation (HRSI) tile taken from the Space Shuttle orbiter was subjected to a nominal heating rate of 60 kW/sq m in the laboratory. The surface temperature response to this heating was measured and used as input to a computer program which computed the applied heating rate. The program is part of a software system that is used to infer convective heating rates to the orbiter thermal protection system during entry. The measured and computed heating rates are compared. Results confirm the applicability of this program to the determination of flight heat transfer rates from flight measured surface temperature data.

Wells, W. L.↗
NASA NTRS2004

Effect of Surface Treatments on Electron Beam Freeform Fabricated Aluminum Structures

Electron beam freeform fabrication (EBF3) parts exhibit a ridged surface finish typical of many layer-additive processes. This, post-processing is required to produce a net shape with a smooth surface finish. High speed milling wire electrical discharge machining (EDM), electron beam glazing, and glass bead blasting were performed on EBF3-build 2219 aluminum alloy parts to reduce or eliminate the ridged surface features. Surface roughness, surface residual stress state, and microstructural characteristics were examined for each of the different surface treatment to assess the quality and effect of the surface treatments on the underlying material. The analysis evaluated the effectivenes of the different surface finishing techniques for achieving a smooth surface finish on an electron beam freeform fabricated part.

Taminger, Karen M. B.↗
NASA NTRS2008

Constraining Particle Variation in Lunar Regolith for Simulant Design

Simulants are used by the lunar engineering community to develop and test technologies for In Situ Resource Utilization (ISRU), excavation and drilling, and for mitigation of hazards to machinery and human health. Working with the United States Geological Survey (USGS), other NASA centers, private industry and academia, Marshall Space Flight Center (MSFC) is leading NASA s lunar regolith simulant program. There are two main efforts: simulant production and simulant evaluation. This work requires a highly detailed understanding of regolith particle type, size, and shape distribution, and of bulk density. The project has developed Figure of Merit (FoM) algorithms to quantitatively compare these characteristics between two materials. The FoM can be used to compare two lunar regolith samples, regolith to simulant, or two parcels of simulant. In work presented here, we use the FoM algorithm to examine the variance of particle type in Apollo 16 highlands regolith core and surface samples. For this analysis we have used internally consistent particle type data for the 90-150 m fraction of Apollo core 64001/64002 from station 4, core 60009/60010 from station 10, and surface samples from various Apollo 16 stations. We calculate mean modal compositions for each core and for the group of surface samples and quantitatively compare samples of each group to its mean as a measurement of within-group variance; we also calculate an FoM for every sample against the mean composition of 64001/64002. This gives variation with depth at two locations and between Apollo 16 stations. Of the tested groups, core 60009/60010 has the highest internal variance with an average FoM score of 0.76 and core 64001/64002 has the lowest with an average FoM of 0.92. The surface samples have a low but intermediate internal variance with an average FoM of 0.79. FoM s calculated against the 64001/64002 mean reference composition range from 0.79-0.97 for 64001/64002, from 0.41-0.91 for 60009/60010, and from 0.54-0.93 for the surface samples. Six samples fall below 0.70, and they are also the least mature (i.e., have the lowest I(sub s)/FeO). Because agglutinates are the dominant particle type and the agglutinate population increases with sample maturity (I(sub s)/FeO), the maturity of the sample relative to the reference is a prime determinant of the particle type FoM score within these highland samples.

Schrader, Christian M.↗
NASA NTRS2009

Stress Analysis of Bolted, Segmented Cylindrical Shells Exhibiting Flange Mating-Surface Waviness

Bolted, segmented cylindrical shells are a common structural component in many engineering systems especially for aerospace launch vehicles. Segmented shells are often needed due to limitations of manufacturing capabilities or transportation issues related to very long, large-diameter cylindrical shells. These cylindrical shells typically have a flange or ring welded to opposite ends so that shell segments can be mated together and bolted to form a larger structural system. As the diameter of these shells increases, maintaining strict fabrication tolerances for the flanges to be flat and parallel on a welded structure is an extreme challenge. Local fit-up stresses develop in the structure due to flange mating-surface mismatch (flange waviness). These local stresses need to be considered when predicting a critical initial flaw size. Flange waviness is one contributor to the fit-up stress state. The present paper describes the modeling and analysis effort to simulate fit-up stresses due to flange waviness in a typical bolted, segmented cylindrical shell. Results from parametric studies are presented for various flange mating-surface waviness distributions and amplitudes.

Knight, Norman F., Jr.↗
NASA NTRS1987

Solution of the surface Euler equations for accurate three-dimensional boundary-layer analysis of aerodynamic configurations

The three-dimensional boundary-layer equations in the limit as the normal coordinate tends to infinity are called the surface Euler equations. The present paper describes an accurate method for generating edge conditions for three-dimensional boundary-layer codes using these equations. The inviscid pressure distribution is first interpolated to the boundary-layer grid. The surface Euler equations are then solved with this pressure field and a prescribed set of initial and boundary conditions to yield the velocities along the two surface coordinate directions. Results for typical wing and fuselage geometries are presented. The smoothness and accuracy of the edge conditions obtained are found to be superior to the conventional interpolation procedures.

Iyer, V.↗
NASA NTRS2012

Analysis of Microcrafters in Materials Specimens after Long-Term Exposure on ISS Surface

The "Komplast" experiment has been carried out on the ISS by the Khrunichev Space Center jointly with other Russian scientific centers since 1998. The experiment incorporates the "Komplast" cartridges on the FGB exterior, which are fitted with materials specimens and sensors. The cartridges were sent into orbit together with FGB on 20 November 1998. In March 2011, two of the cartridges were taken back from the ISS by the "Discovery" American space shuttle after being exposed in the open space for 12 years. In the framework of this experiment the subject of analysis is the effect of the space environment on the exposed specimens of various materials. This report covers the analysis results of the surface morphology of various materials taken from the "Komplast" cartridges exposed to hits of micrometeors and micronic particles of space debris. Analysis is made of microcraters of 5 to 250 mcm in specimens of polished metals and silicone comprised in the sensor for micrometeoric particles. The report represents optic and scanning electron microscope images of craters formed in the specimens by high-velocity and low-velocity particles impacting the surface. By virtue of the electronic microscope, data on composition of the substance in the craters and of the substance of the low-velocity particles are obtained. The data make it possible to differentiate the particles as the natural-origin particles or anthropogenic-origin space debris particles. Distribution of craters and low-velocity particles in the size range of 5 to 50 mcm is obtained. The data are compared with the existing models of fluxes of natural-origin and artificial-origin microparticles on the ISS orbit. Inhomogeneous particles of complicated configuration are discovered on the surface of the analyzed specimens, whose origin are not uniquely determined and are to be the subject of further study.

Shaevich, S. K.↗
NASA NTRS2001

Software Package Completed for Alloy Design at the Atomic Level

As a result of a multidisciplinary effort involving solid-state physics, quantum mechanics, and materials and surface science, the first version of a software package dedicated to the atomistic analysis of multicomponent systems was recently completed. Based on the BFS (Bozzolo, Ferrante, and Smith) method for the calculation of alloy and surface energetics, this package includes modules devoted to the analysis of many essential features that characterize any given alloy or surface system, including (1) surface structure analysis, (2) surface segregation, (3) surface alloying, (4) bulk crystalline material properties and atomic defect structures, and (5) thermal processes that allow us to perform phase diagram calculations. All the modules of this Alloy Design Workbench 1.0 (ADW 1.0) are designed to run in PC and workstation environments, and their operation and performance are substantially linked to the needs of the user and the specific application.

Bozzolo, Guillermo H.↗