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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Pit Stability Predictions of Additively Manufactured SS316 Surfaces Using Finite Element Analysis

Stainless steels are susceptible to localized forms of corrosion attack, such as pitting. The size and lifetime of a nucleated pit can vary, depending on a critical potential or current density criterion, which determines if the pit repassivates or continues growing. This work uses finite element method (FEM) modeling to compare the critical pit radii predicted by thermodynamic and kinetic repassivation criteria. Experimental electrochemical boundary conditions are used to capture the active pit kinetics. Geometric and environmental parameters, such as the pit shape and size (analogous to additively manufactured lack-of-fusion pores), solution concentration, and water layer thickness were considered to assess their impact on the pit repassivation criterion. The critical pit radius (the transition point from stable growth to repassivation) predicted for a hemispherical pit was larger when using the repassivation potential (E rp ) criteria, as opposed to the current density criteria (pit stability product). Including both the pit stability product and E rp into its calculations, the analytical maximum pit model predicted a critical radius two times more conservative than the FEA approach, under the conditions studied herein. The complex pits representing lack-of-fusion pores were shown to have minimal impact on the critical radius in atmospheric conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Tardigrade, Version 1.1x

Tardigrade is a collection of functions, libraries, and stand-alone code which enables the simulation of materials using the higher-order micromorphic framework. The tools present are the interface to INL's MOOSE code which is used as the underlying FEA solver, several constitutive equations (linear elasticity, a pressure-sensitive elasto-plastic model, crystal plasticity, and additional models for geo-materials) useful for demonstration purposes and the simulation of some materials, the micromorphic filter which converts DNS information to micromorphic stress-deformation quantities, and the overlap coupling framework which enables multi-scale simulations of a coupled higher-order macroscale and a classically defined microscale.

Miller, Nathan↗
DOE OSTI2025

Analysis Background & Noise in Stretched Wire Alignment Technique Measurements

The Stretched-Wire Alignment Technique (SWAT) is one method of magnet alignment for linear induction accelerators. The applications of SWAT have been implemented for aligning solenoid magnets on the Scorpius linear induction accelerator which will be sited at the Nevada National Security Site and the Flash X-Ray (FXR) linear induction accelerator at Lawrence Livermore National Laboratory’s Contained Firing Facility. This article describes both systematic (repeatable) and random sources of background and noise as well as practical ways to eliminate or reduce them to acceptable levels. Systematic sources include reflections from wire ends, rapid sag due to ohmic heating of the wire, magnetic materials, and shot rate. Random sources include air currents, vibration of nearby equipment, mechanical stability of test equipment, and the instruments used to measure the wire motion. Mitigations include curve fitting and adaptive noise signal cancellation, and mechanical damping. Finite Element Analysis (FEA) was used to identify and resolve a repeatable wire vibration frequency interfering with the signal resolution. Two stretched wire alignment technique set ups from Sandia National Labs and Lawrence Livermore National Lab have shown background noise sources and ways of mitigating them by either analysis methods or change of mechanical configuration. Conclusions that were drawn included the severe sensitivity of the deflection to even small external interferences of the SWAT wire such that it requires attention to detail in mechanical set up and analysis.

Linear Inductive Accelerator↗
DOE OSTI2022

TEAMER: Sandia and CalWave Torque Spring Assessment

Power-take-off (PTO) systems for wave energy converters (WEC) require restoring forces for efficient hydrodynamic as well as mechanical to electric power transfer. Implementation of an effective spring mechanism that can provide a restoring torque on e.g. a rotational, winch type PTO shaft is challenging. SNL in collaboration with CalWave, will use numerical finite element simulations to study application of mechanical torsion springs as a highly efficient restoring force element for CalWave's rotational PTO. Material studies will include common steel as a baseline and potentially advanced materials such as fiber composite materials with different cross-sectional profiles. Test report including description and results of FEA (finite element analysis) models. Excel sheet summarizes which scripts were used for which tables and figures in the report. Part of TEAMER request for technical support (RFTS 1) award to CalWave and Sandia National Lab (SNL).

16 TIDAL AND WAVE POWER↗
DOE OSTI2021

Synthesis and behavior of bulk iron nitride soft magnets via high-pressure spark plasma sintering

Abstract In this study, dense bulk iron nitrides (Fe x N) were synthesized for the first time ever using spark plasma sintering (SPS) of Fe x N powders. The Fe 4 N phase of iron nitride in particular has significant potential to serve as a new soft magnetic material in both transformer and inductor cores and electrical machines. The density of SPSed Fe x N increased with SPS temperature and pressure. The microstructure of the consolidated bulk Fe x N was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) magnetometry. XRD revealed a primary phase of Fe 4 N with secondary phases of Fe 3 N and metallic iron. Finite element analysis (FEA) was also applied to investigate and explain localized heating and temperature distribution during SPS. The effects of processing on interface bonding formation and phase evolution were investigated and discussed in detail to provide insight into fundamental phenomena and microstructural evolution in SPSed Fe x N. Graphic abstract

36 MATERIALS SCIENCE↗
DOE OSTI2023

Statistical methods for design and testing of 3D-printed polymers

Different statistical methods are used in various fields to qualify processes and products, especially in emerging technologies like Additive Manufacturing (AM) or 3D printing. Since several statistical methods are being employed to ensure quality production of the 3D-printed parts, an overview of these methods used in 3D printing for different purposes is presented in this paper. The advantages and challenges, to understanding the importance it brings for design and testing optimization of 3D-printed parts are also discussed. The application of different metrology methods is also summarized to guide future researchers in producing dimensionally-accurate and good-quality 3D-printed parts. Here, this review paper shows that the Taguchi Methodology is the commonly-used statistical tool in optimizing mechanical properties of the 3D-printed parts, followed by Weibull Analysis and Factorial Design. In addition, key areas such as Artificial Intelligence (AI), Machine Learning (ML), Finite Element Analysis (FEA), and Simulation require more research for improved 3D-printed part qualities for specific purposes. Future perspectives are also discussed, including other methods that can help further improve the overall quality of the 3D printing process from designing to manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2023

On the 3D printability of one-part moisture-curable polyurethanes via direct ink writing (DIW)

Direct ink writing (DIW) is an ambient temperature additive manufacturing (AM) method that accommodates many possible ink materials. Here, in this work, we demonstrate using a moisture-curable commercially available polyurethane (PU) sealant as an alternative ink for DIW. We discussed the fundamentals of PU chemistry and determined the best 3D printing parameters. Studies on rheological, thermogravimetric, spectroscopic characterization, and initial finite element analyses (FEA) showed properties expected from a performance sealant with high elongation and low modulus of a 3D-printed object. This affirms the flexibility of the DIW technique as an accessible AM method amenable for future materials development from commercial model formulations.

36 MATERIALS SCIENCE↗
DOE OSTI2021

High flux boiling heat transfer enhancement using triangle shaped vertical walls in two-phase microchannel heat exchangers

Two-phase heat exchangers allow heat loads to be dissipated with lower fluid flow rates without inducing thermal gradients, and high surface area microchannels further reduce the thermal resistance of these heat exchangers. However, there are many practical limits that prevent widespread use of two-phase microchannel heat exchangers. Many authors have looked to address these practical limits by treating the channel floors or creating artificial nucleation sites. Few works look to enhance heat transfer in the walls of channels with hydraulic diameters below 200 μm. This work is aimed at increasing the efficacy of high aspect ratio silicon microchannels that use R134a as the working fluid. The 125 parallel channels are 40 μm wide, 200 μm deep, and 2 mm long and contain a 15 μm wide, 150 μm long restriction at each inlet. The thermal resistance and dryout characteristics of traditional, plain-walled channels are compared to channels with 2 area enhancement patterns each of which increases the area available for heat transfer by 41%. Furthermore, a resistance to dryout is seen in both area-enhanced test sections, and a 15.5% reduction in thermal resistance is shown for the area-enhanced part with a 6 μm triangular pitch. Only a 7.8% performance increase is seen in the test section with a 3 μm pitch. Both area enhancement patterns induce an average 27% increase in pressure drop for all tests. Heat transfer characteristics are solved for using a finite element analysis (FEA) model. By examining heat transfer coefficients and local heat fluxes, it is postulated that the area enhancement reduces heat transfer coefficients and the performance increase is caused by increasing the number of active nucleation sites.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on CeCdAsO by Materials Project

CeOCdAs is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce3+ is bonded in a 4-coordinate geometry to four equivalent As3- and four equivalent O2- atoms. All Ce–As bond lengths are 3.34 Å. All Ce–O bond lengths are 2.38 Å. Cd2+ is bonded to four equivalent As3- atoms to form a mixture of distorted edge and corner-sharing CdAs4 tetrahedra. All Cd–As bond lengths are 2.81 Å. As3- is bonded in a 8-coordinate geometry to four equivalent Ce3+ and four equivalent Cd2+ atoms. O2- is bonded to four equivalent Ce3+ atoms to form a mixture of edge and corner-sharing OCe4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(PIr)2 by Materials Project

BaIr2P2 is Parent of FeAs superconductors-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba is bonded in a body-centered cubic geometry to eight equivalent P atoms. All Ba–P bond lengths are 3.40 Å. Ir is bonded to four equivalent P atoms to form a mixture of distorted edge and corner-sharing IrP4 tetrahedra. All Ir–P bond lengths are 2.38 Å. P is bonded in a 8-coordinate geometry to four equivalent Ba and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCuSF by Materials Project

SrCuFS is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sr2+ is bonded in a 4-coordinate geometry to four equivalent S2- and four equivalent F1- atoms. All Sr–S bond lengths are 3.17 Å. All Sr–F bond lengths are 2.48 Å. Cu1+ is bonded to four equivalent S2- atoms to form a mixture of corner and edge-sharing CuS4 tetrahedra. All Cu–S bond lengths are 2.43 Å. S2- is bonded in a 4-coordinate geometry to four equivalent Sr2+ and four equivalent Cu1+ atoms. F1- is bonded to four equivalent Sr2+ atoms to form a mixture of corner and edge-sharing FSr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaZnSbO by Materials Project

LaOZnSb is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. La3+ is bonded in a 4-coordinate geometry to four equivalent Sb3- and four equivalent O2- atoms. All La–Sb bond lengths are 3.57 Å. All La–O bond lengths are 2.42 Å. Zn2+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing ZnSb4 tetrahedra. All Zn–Sb bond lengths are 2.75 Å. Sb3- is bonded in a 8-coordinate geometry to four equivalent La3+ and four equivalent Zn2+ atoms. O2- is bonded to four equivalent La3+ atoms to form a mixture of distorted edge and corner-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdZnSbO by Materials Project

NdOZnSb is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Nd3+ is bonded in a 4-coordinate geometry to four equivalent Sb3- and four equivalent O2- atoms. All Nd–Sb bond lengths are 3.54 Å. All Nd–O bond lengths are 2.38 Å. Zn2+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing ZnSb4 tetrahedra. All Zn–Sb bond lengths are 2.74 Å. Sb3- is bonded in a 8-coordinate geometry to four equivalent Nd3+ and four equivalent Zn2+ atoms. O2- is bonded to four equivalent Nd3+ atoms to form a mixture of distorted edge and corner-sharing ONd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbZnSn2 by Materials Project

TbZnSn2 is Parent of FeAs superconductors-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Tb is bonded to four equivalent Zn and eight Sn atoms to form a mixture of face, edge, and corner-sharing TbZn4Sn8 cuboctahedra. All Tb–Zn bond lengths are 3.28 Å. There are four shorter (3.16 Å) and four longer (3.32 Å) Tb–Sn bond lengths. Zn is bonded in a 12-coordinate geometry to four equivalent Tb and four equivalent Sn atoms. All Zn–Sn bond lengths are 2.85 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Tb and four equivalent Zn atoms. In the second Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Tb and four equivalent Sn atoms. All Sn–Sn bond lengths are 3.10 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaCuTeF by Materials Project

BaCuTeF is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ba2+ is bonded in a 4-coordinate geometry to four equivalent Te2- and four equivalent F1- atoms. All Ba–Te bond lengths are 3.59 Å. All Ba–F bond lengths are 2.69 Å. Cu1+ is bonded to four equivalent Te2- atoms to form a mixture of corner and edge-sharing CuTe4 tetrahedra. All Cu–Te bond lengths are 2.69 Å. Te2- is bonded in a 12-coordinate geometry to four equivalent Ba2+ and four equivalent Cu1+ atoms. F1- is bonded to four equivalent Ba2+ atoms to form a mixture of corner and edge-sharing FBa4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on EuCuTeF by Materials Project

EuCuTeF is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Eu2+ is bonded in a 4-coordinate geometry to four equivalent Te2- and four equivalent F1- atoms. All Eu–Te bond lengths are 3.37 Å. All Eu–F bond lengths are 2.54 Å. Cu1+ is bonded to four equivalent Te2- atoms to form CuTe4 tetrahedra that share corners with four equivalent CuTe4 tetrahedra, corners with twelve equivalent FEu4Te4 tetrahedra, edges with two equivalent FEu4Te4 tetrahedra, and edges with four equivalent CuTe4 tetrahedra. All Cu–Te bond lengths are 2.67 Å. Te2- is bonded in a 12-coordinate geometry to four equivalent Eu2+, four equivalent Cu1+, and four equivalent F1- atoms. All Te–F bond lengths are 3.64 Å. F1- is bonded to four equivalent Eu2+ and four equivalent Te2- atoms to form FEu4Te4 tetrahedra that share corners with twelve equivalent CuTe4 tetrahedra, edges with two equivalent CuTe4 tetrahedra, edges with four equivalent FEu4Te4 tetrahedra, and faces with four equivalent FEu4Te4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaAgTeF by Materials Project

BaAgTeF is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ba2+ is bonded in a 4-coordinate geometry to four equivalent Te2- and four equivalent F1- atoms. All Ba–Te bond lengths are 3.64 Å. All Ba–F bond lengths are 2.71 Å. Ag1+ is bonded to four equivalent Te2- atoms to form distorted AgTe4 tetrahedra that share corners with four equivalent AgTe4 tetrahedra, corners with twelve equivalent FBa4Te4 tetrahedra, edges with two equivalent FBa4Te4 tetrahedra, and edges with four equivalent AgTe4 tetrahedra. All Ag–Te bond lengths are 2.92 Å. Te2- is bonded in a 12-coordinate geometry to four equivalent Ba2+, four equivalent Ag1+, and four equivalent F1- atoms. All Te–F bond lengths are 3.87 Å. F1- is bonded to four equivalent Ba2+ and four equivalent Te2- atoms to form FBa4Te4 tetrahedra that share corners with twelve equivalent AgTe4 tetrahedra, edges with two equivalent AgTe4 tetrahedra, edges with four equivalent FBa4Te4 tetrahedra, and faces with four equivalent FBa4Te4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2CuGe4 by Materials Project

CuGe4Hf2 is Parent of FeAs superconductors-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded to four equivalent Cu and eight Ge atoms to form distorted HfCu4Ge8 cuboctahedra that share corners with four equivalent HfCu4Ge8 cuboctahedra, edges with four equivalent HfCu4Ge8 cuboctahedra, edges with eight equivalent CuHf4Cu4Ge4 cuboctahedra, faces with four equivalent HfCu4Ge8 cuboctahedra, and faces with four equivalent CuHf4Cu4Ge4 cuboctahedra. There are two shorter (3.05 Å) and two longer (3.07 Å) Hf–Cu bond lengths. There are four shorter (2.80 Å) and four longer (2.87 Å) Hf–Ge bond lengths. In the second Hf site, Hf is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Hf–Ge bond distances ranging from 2.77–3.14 Å. Cu is bonded to four equivalent Hf, four equivalent Cu, and four equivalent Ge atoms to form distorted CuHf4Cu4Ge4 cuboctahedra that share corners with four equivalent CuHf4Cu4Ge4 cuboctahedra, edges with eight equivalent HfCu4Ge8 cuboctahedra, faces with four equivalent HfCu4Ge8 cuboctahedra, and faces with eight equivalent CuHf4Cu4Ge4 cuboctahedra. All Cu–Cu bond lengths are 2.69 Å. There are two shorter (2.49 Å) and two longer (2.50 Å) Cu–Ge bond lengths. There are four inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.69 Å. In the second Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Hf and four equivalent Cu atoms. In the third Ge site, Ge is bonded in a 4-coordinate geometry to six equivalent Hf and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.65 Å. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗