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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

AMS / BARC Joint Survey Addendum Technical Report

This report details the data analysis results from data collected during the September-October 2019 joint survey series between the Department of Energy (DOE) National Nuclear Security Administration (NNSA) Aerial Measuring System (AMS) asset, and the Government of India’s Department of Atomic Energy (DAE) Bhabha Atomic Research Centre (BARC). This joint survey series took place at the Nevada National Security Site (NNSS), areas of public land in Southern Nevada, and at the DOE Office of Legacy Management (LM) Large Area Calibration Pads (LACP) at the Grand Junction Regional Airport in Grand Junction, CO. The data detailed in this report were gathered at the LACP. More details regarding the setup of these surveys and personnel involvement can be found in the AMS / BARC Joint Survey Summary Report. The data from the LACP collected by AMS are consistent with past data collection campaigns at the LACP. The AMS Bell 412 (B412) helicopter, equipped with both the standard AMS thallium-doped sodium iodide (NaI(Tl)) 2"x4"x16" 12-detector system and a subset of the BARC Aerial Gamma Spectroscopy System (AGSS) consisting of two independent 3"x3"cylindrical NaI(Tl) detectors, measured each of the five calibration pads for a minimum of 10 minutes. After the helicopter measurements, a pressurized ion chamber (PIC) was used to directly measure radiation exposure rates on each of the pads for a period 5 minutes. The geophysical calibration procedure published by the International Atomic Energy Agency (IAEA) (Erdi-Krausz et al. 2003) was used to determine the spectral stripping sensitivity matrix for naturally occurring radiological material (NORM). The sensitivity matrix is consistent with the AMS long term average. Additionally, the PIC data was used to calibrate the AMS system for exposure rate. The results of the exposure rate analysis are also consistent with AMS long-term averages.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Joint Regulatory Expectations for Land Quality Management at UK Nuclear Sites - 16596

Across the UK a variety of policies and legislation can apply to the management of land quality and several regulators are involved. The risk that such complexity could hamper or delay the delivery of decommissioning and clean-up at nuclear sites, has led to the UK regulators developing a suite of joint expectations for land quality management together with working-together arrangements to support the delivery of these. The UK regulators, in recognition of the complexity of the UK policy and legal framework applying to land contamination on nuclear sites, have collaborated to agree a set of 'joint expectations' for LQM. They address the prevention of contamination and the management of contaminated land and groundwater. They expectations are consistent with regulatory requirements, but provide a simple set of principles that can be applied to all sites and types of potential contamination. This has the advantage of supporting early dialogue with operators and land owners to allow priorities to be agreed and resourced. They also support wider communication with other stakeholders. The UK regulators have embarked on several follow up activities to build on the work in establishing the joint expectations and look for further areas where collaboration will be beneficial.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Dual-wall integrated flange joint

A dual-wall integrated flange joint is provided. The integrated flange joint includes an inner wall having at least one inlet and at least one outlet, a flange extending radially outward from the inlet of the inner wall, and a collar extending from the flange in the direction of the inner wall and surrounding at least a portion of the inner wall. The integrated flange joint is formed of a single piece of material. Also, the collar at least partially defines an outer wall, and a volume between the collar and the inner wall at least partially defines an airgap.

Hoye, Robert F.↗
NASA NTRS1995

(abstract) Characterization of Structural Response for Systems with Loose Joints

This paper describes a technique to locate and characterize loose joints in a large truss structure to generate an accurate structural model. The joint looseness is modeled as a gap in the member that opens and closes depending on the loading. Arbitrarily placed actuators are used to prestress the structure to first linearize the response. Next the actuator displacements are systematically reduced while monitoring the displacement response. The gap locations are determined by comparing the measured displacements with sets of calculated displacements and the sizes are estimated by monitoring the gap member length changes using the appropriate linear force-displacement relationship for the load level. The effect of measurement error in the truss displacements and the actuator length changes are investigated.

truss structures loose joints displacements actuat↗
NASA NTRS2004

Co-axial Joint Technology Applied to Antenna Backup Structures

The increasing demand to improve focusing accuracy and to accommodate higher frequencies in space communications and radio astronomy has created significant challenges for improving the capability of the constituent systems in radio antennas and telescopes. One important system is the radio antenna/telescope backup structure connections. The backup structure is a key element in providing a stable, precise and rigid support for the reflective surface. The ideal connection for these types of structures is rigid and concentric resulting in minimal deformation with stress/strain curves that are linear, repeatable and exhibiting no hysteresis over the entire service load range. Conceivably such a connection could be designed so that the stress/strain curve mimics the stress/strain characteristics of the connecting member in both tension and compression. When this is achieved then such joints can be said to be 'invisible' in the global behavior of the backup structure. At that point, overall reflector deflection becomes more linear and highly predictable. In conjunction with this advantage, optimized backup structure geometries, adaptive reflectors and compensating algorithms can best be applied in producing an instrument of unparalleled performance. This paper introduces Co-Axial Joint (CAJ) technology as the practical and economical means to produce an invisible connection.

trusses↗
DOE OSTI2018

Microstructure and Mechanical Properties of Dissimilar Joints of Al-Mg{sub 2}Si and 5052 Aluminum Alloy by Friction Stir Welding

Al-Mg{sub 2}Si alloy and 5052 Al alloy were welded successfully by friction stir welding (FSW) in this study. The results show that the alloy consists of three distinct zones after FSW: the base material zone (BMZ), the transitional zone, and the weld nugget (WN). The morphologies of the primary Mg{sub 2}Si phases are identified as coarse equiaxed crystals for Al-Mg{sub 2}Si alloys in the BMZ. The WN is a mixture of rich Al-Mg{sub 2}Si and rich 5052 alloy, and a banded structure is formed in the zone. Interestingly, in the WN, the equiaxed crystals changed to polygonal particles with substantially reduced sizes in the rich Al-Mg{sub 2}Si zone. However, in addition to the white rich Mg phase appearing in the rich 5052 zone near the interface, the 5052 alloy does not show obvious changes. The hardness gradually increases from the BMZ of the 5052 to the welded joint to the Al-Mg{sub 2}Si BMZ. In addition, the ultimate tensile strength (UTS) of the welded joint is higher than that of the base material of the Al-Mg{sub 2}Si, whereas it is lower than that of the 5052 base alloy. The results of the elongation are similar to the UTS results. The fracture mechanism is also investigated.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Investigation of Hydrogen Embrittlement Susceptibility of X80 Weld Joints by Thermal Simulation

The objective of this study was to investigate the hydrogen embrittlement (HE) susceptibility and influence mechanism of X80 weld joints. Slow strain rate testing (SSRT) under in situ H-charging, combined with microstructure and fracture analysis, was performed on the base metal (BM), weld metal (WM), thermally simulated fine-grained heat-affected zone (FGHAZ) and coarse-grained heat-affected zone (CGHAZ). Results showed that the WM and simulated HAZ had a greater degree of high local strain distribution than the BM; compared to the CGHAZ, the FGHAZ had lower microhardness and more uniformly distributed stress. SSRT results showed that the weld joint was highly sensitive to HE; the HE index decreased in the following sequence: FGHAZ, WM, CGHAZ and BM. The effect of the microstructure on HE was mainly reflected in microstructure, local stress distribution and microhardness.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Formation of Lamellar Carbides in Alloy 617-HAZ and Their Role in the Impact Toughness of Alloy 617/9%Cr Dissimilar Welded Joint

The relationship between the microstructure and impact toughness, especially the formation of the lamellar carbides and its effect on the impact toughness of the heat-affected zone of Alloy 617 (Alloy 617-HAZ), was systematically investigated. Impact test was performed on Alloy 617/9%Cr dissimilar welded joints aged for different time at 620 °C. The results showed that the characteristic zones of the whole welded joint revealed decreased impact toughness with increasing the aging time. The impact energies in weld metal showed high stability despite the aging process, while the Alloy 617-HAZ for all testing specimens presented the lowest impact toughness with various aging time. Meanwhile, the mixed grains were found in the base metal (BM) and heat-affected zone of Alloy 617, together with the twins with different widths located in the interior of the large grains. The columnar and equiaxed grain zones appear alternately due to the multilayer and multi-pass welding technique. In particular, compared with Alloy 617-BM, coarsened and even lamellar carbides were observed in Alloy 617-HAZ. These special carbides can separate the grains and therefore result in the formation of intergranular fracture morphology in Alloy 617-HAZ. Besides, the microhardness distribution was tested with a proper load, and the results exhibited that the weld possessed the highest hardness for all specimens with various aging time. The higher microhardness in Alloy 617-HAZ compared with that in Alloy 617-BM was attributed to the high density of the dislocations, which could be detected by transmission electron microscope. As a result, the coarsened carbides aggregated in the grain boundaries to form the lamellar layer are deemed as the main factor to reduce the impact toughness in Alloy 617-HAZ.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Modeling of Keyhole-Induced Pore Formation in Laser-Arc Hybrid Welding of Aluminum Alloy with a Horizontal Fillet Joint

A three-dimensional transient model is proposed to investigate the weld pool dynamic behavior in laser + metal inert gas (MIG) hybrid fillet welding of aluminum alloy in the horizontal position, which allows for the joint configuration and coupling of the keyhole, droplet and weld pool as well as the heat and mass exchange between gas and liquid phases and is able to simulate the temperature distribution, fluid flow and formation process of a keyhole-induced pore in hybrid welding with a horizontal fillet joint. The weld porosity is also measured using x-ray nondestructive testing technology. Keyhole behavior and the formation mechanism of keyhole-induced porosity were analyzed. The calculated results are in generally good agreement with the experimental ones. A clockwise vortex always exists at the middle part of the weld pool. The formation and growth of the molten metal bulge on the keyhole wall are responsible for the occurrence of a gas bubble, which has a variation in size and shape and can be split during welding. The keyhole collapses easily at its middle or upper part in horizontal fillet welding, and the capture of the bubble by the upper molten pool boundary enhances the possibility of porosity formation to some degree. The keyhole-induced pore is mainly formed at the regions near the keyhole bottom and the upper fusion line of the weld pool.

36 MATERIALS SCIENCE↗
DOE OSTI2015

In-vitro and in-vivo imaging of MMP activity in cartilage and joint injury

Non-destructive detection of cartilage-degrading activities represents an advance in osteoarthritis (OA) research, with implications in studies of OA pathogenesis, progression, and intervention strategies. Matrix metalloproteinases (MMPs) are principal cartilage degrading enzymes that contribute to OA pathogenesis. MMPSense750 is an in-vivo fluorimetric imaging probe with the potential to continuously and non-invasively trace real-time MMP activities, but its use in OA-related research has not been reported. Our objective is to detect and characterize the early degradation activities shortly after cartilage or joint injury with MMPSense750. We determined the appropriate concentration, assay time, and linear range using various concentrations of recombinant MMPs as standards. We then quantified MMP activity from cartilage explants subjected to either mechanical injury or inflammatory cytokine treatment in-vitro. Finally, we performed in-vivo MMP imaging of a mouse model of post-traumatic OA. Our in-vitro results showed that the optimal assay time was highly dependent on the MMP enzyme. In cartilage explant culture media, mechanical impact or cytokine treatment increased MMP activity. Injured knees of mice showed significantly higher fluorescent signal than uninjured knees. We conclude that MMPSense750 detects human MMP activities and can be used for in-vitro study with cartilage, as well as in-vivo studies of knee injury, and can offering real-time insight into the degradative processes that occurring within the joint before structural changes become evident radiographically. - Highlights: • MMPSense750 is near-infrared fluorescent probe which can detect MMP activity. • MMPSense750 can detect human MMP-3, -9, and -13. • The reaction kinetics with MMPSense750 were different for the three MMPs. • MMPSense750 can visualized real time MMP activity in mouse injured knees. • MMPSense750 is convenient tool to evaluate real-time MMP activity non-invasively.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint

Evolution of microstructure, micro-hardness and micro-tensile strength behavior was investigated in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint after the artificial aging at 350 °C for 3000 h. After detailed characterization of microstructures in optical microscopy, scanning electron microscopy and transmission electron microscopy, it is revealed that the change of martensite–bainite constituent promotes more homogeneous microstructure distribution. The aging treatment facilitates redistribution of carbon and chromium elements along the welded joint, and the micro-hardness is increased slightly through the welds due to enrichment of carbon. The types of precipitates in the weldment mainly include M{sub 3}C, MC, M{sub 2}C and M{sub 23}C{sub 6}. The carbides in base metal, weld metal and coarse-grained heat-affected zone are prone to change from ellipsoidal to platelet form whereas more uniform spherical carbides are observed in the fine-grained zone. Precipitation and coarsening of M{sub 23}C{sub 6} near the fusion line, and formation of MC and M{sub 2}C, are responsible for the tensile strength decrease and its smooth distribution in the aged heat-affected zone. This implies that the thermal aging can relieve strength mismatch in the weldments. - Highlights: • Microstructure homogeneity improved in HAZ after long-term aging. • Tensile strength decreased in HAZ due to precipitation and coarsening of M{sub 23}C{sub 6}. • Strength mismatch in NiCrMoV steel welds was relieved after aging at 350 °C × 3000 h.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructural characterization of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint

The microstructure of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint was characterized in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction) and micro-hardness testing. Epitaxial growth and competitive growth are evident in the 308L–316L fusion boundary regions. A martensite layer, carbon-depleted zones, and type-II and type-I boundaries are found in the SA508–309L fusion boundary regions, while only martensite and austenite mixed zones are observed in the SA508–308L fusion boundary regions. The microstructure near the fusion boundary and the microstructure transition in the SA508 heat affected zone are quite complex. Both for SA508–309L/308L and 308L–316L, the highest residual strain is located on the outside of the weldment. The residual strain and the grain boundary character distribution change with increasing distance from the fusion boundary in the heat affected zone of 316L. Micro-hardness measurements also reveal non-uniform mechanical properties across the weldment. - Highlights: • The microstructure of SA508 HAZ, especially near the FB, is very complex. • The outside of the dissimilar metal welded joint has the highest residual. • The micro-hardness distributions along the DMWJ are non-uniform.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructural characterization and mechanical properties of high power ultrasonic spot welded aluminum alloy AA6111–TiAl6V4 dissimilar joints

Aluminum alloy AA6111 and TiAl6V4 dissimilar alloys were successfully welded by high power ultrasonic spot welding. No visible intermetallic reaction layer was detected in as-welded AA6111/TiAl6V4 welds, even when transmission electron microscopy was used. The effects of welding time and natural aging on peak load and fracture energy were investigated. The peak load and fracture energy of welds increased with an increase in welding time and then reached a plateau. The lap shear strength (peak load) can reach the same level as that of similar Al–Al joints. After natural aging, the fracture mode of welds transferred from ductile fracture of the softened aluminum to interfacial failure due to the strength recovery of AA6111. - Highlights: • Dissimilar Al/Ti welds were produced by high power ultrasonic spot welding. • No visible intermetallic reaction layer was detected on weld interface. • The lap shear strength can reach the same level as that of similar Al–Al joints. • The fracture mode becomes interfacial failure after natural aging.

36 MATERIALS SCIENCE↗
DOE OSTI2017

In situ investigation of the tensile deformation of laser welded Ti{sub 2}AlNb joints

The tensile deformation behavior of laser welded Ti{sub 2}AlNb joints was investigated using in situ analysis methods. The fracture mode of the single-B2-phase fusion zone was quasi-cleavage at room temperature and intergranular at 650 °C, while that of base metal was microvoid coalescence at both room temperature and 650 °C. Tensile deformation at room temperature was observed using in situ SEM tensile testing. In base metal, microcracks nucleated and propagated mainly within the O phase or along O/B2 phase boundaries. While both the cross- and multi-slips were found in the single-B2-phase fusion zone, a confocal laser scanning microscopy was used to observe the crack initiation and propagation process in situ at 650 °C. Cracks mainly formed along the B2/O phase boundaries in base metal, along the fragile grain boundaries of B2 phase in the fusion zone. The thermal simulation experiment and following TEM analysis indicated that the precipitation of continuous O-phase films along the B2 grain boundaries resulted in the high temperature brittleness of laser welded Ti{sub 2}AlNb joints. - Highlights: •Cracks formed within O phase or along B2/O boundaries in the base metal. •Cross- and multi-slips relieved stress in the fusion zone at room temperature. •Cracks mainly formed along the B2/O boundaries at 650 °C. •In the fusion zone, intergranular cracks were in situ observed at 650 °C. •O-phase films along B2 grain boundaries caused the high temperature brittleness.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Microstructural variation through weld thickness and mechanical properties of peened friction stir welded 6061 aluminum alloy joints

The current study examined the effect of microstructure variation on the development of mechanical properties in friction stir welded joints of 6061-T6 aluminum alloy, which were subsequently processed by shot peening (SP). Following to FSW, fatigue specimens were extracted perpendicularly to the welding direction. Surface Skimming to 0.5 mm from crown and root sides of the joint was made and SP was later applied on the two sides using ceramic shots of two different Almen intensities of 0.18 mmA and 0.24 mmA. Microstructural examination by electron back scattered diffraction (EBSD) indicated variation in the grain refinement of the weld zone, with coarsest grains (5 μm) at the crown side and finest grains (2 μm) at the root side. Reduction of microhardness to 60 HV occurred in the weld zone for samples in FSW condition. Application of SP promoted significant strain hardening at the crown side, with Almen intensities of 0.24 mmA providing maximum increase in microhardness to 120 HV. On the contrary, only a maximum microhardness of 75 HV was obtained at the root side. The difference in strain hardening capability at the two sides was strongly dependent on grain size. The two Almen intensities produced similar distribution of compressive residual stresses in the subsurface regions that led to enhance the fatigue strength to the level of base metal for N ≥ 10{sup 5} cycles. Yet, the increase in fatigue strength was more pronounced with increasing Almen intensity to 0.24 mmA, demonstrating further enhancement by strain hardening. - Highlights: • Grain refinement was observed after friction stir welding of AA 6061-T6. • Reduction in microhardness and fatigue strength were obtained after welding. • Variation in grain refinement led to different hardening behavior after peening. • Shot peening induced beneficial compressive residual stresses. • Shot peening and surface skimming markedly improved the fatigue performance.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Characterization of Alloy 600 joints exposed to a high-temperature supercritical-carbon dioxide environment

Highlights: • Diffusion-bond showed similar corrosion and carburization behavior as parent matrix. • Diffusion-bond line migrated due to the Cr-depletion induced recrystallization. • Alloy 182 fusion-weld showed larger weight gains with outer Mn-rich oxides. • The presence of SiO{sub 2} in chromia suppressed carburization at the oxide/matrix interface. • Despite larger weight gains, Alloy 182 fusion-weld showed negligible tensile property changes. - Abstract: Two types of Alloy 600 joints, such as diffusion-bonded joint and Alloy 182 fusion-weld, were exposed to supercritical-CO{sub 2} environment at 550 and 650 °C (20 MPa) for 1000 h. The diffusion-bond region showed similar oxidation characteristics as parent Alloy 600, but the migration of diffusion bond line below oxide layer was observed due to the Cr-depletion induced recrystallization. For Alloy 182 fusion-weld, outer Mn-rich oxides (Mn{sub 3}O{sub 4} and MnCr{sub 2}O{sub 4}) and a small amount of inner SiO{sub 2} mixed with chromia were formed due to high Mn and Si contents. The presence of SiO{sub 2} in chromia suppressed carburization at the oxide/matrix interface, which resulted in the formation of an amorphous C layer between the outer Mn-rich oxide and inner Cr-rich oxide. For Alloy 182 fusion-weld, tensile property changes after exposure to supercritical-CO{sub 2} environment were negligible.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Interfacial characterization by TEM and nanoindentation of W-Eurofer brazed joints for the first wall component of the DEMO fusion reactor

Highlights: • Interfacial characterization of W-Eurofer joints by TEM and nanoindentation has been accomplished. • Microstructural and mechanical properties were in complete agreement. • The combination of both nano-techniques allows to obtain valuable information about braze interfaces. - Abstract: The interfacial characterization of W-Eurofer brazed joints, which could be implemented in the first wall component of the future DEMO nuclear fusion reactor, has been carried out by TEM and nanoindentation. The Eurofer-braze interface is characterized by the formation of two reaction layers formed during the melting stage of the filler in the brazing process, which reported high hardness and modulus values. The obtained microstructure supposes a homogenous transition between the base material and the braze. However, in the W-braze interface a more defined interface is formed, where the presence of an intermetallic transition compound has been identified. The combination of both techniques allows to study the resultant microstructure and to analyze the mechanical response of the phases, which constitute the interface and could be helpful to control the brazing conditions avoiding undesirable brazeability problems.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Companions and competitors: Joint metal-supply relationships in gold, silver, copper, lead and zinc mines

Firms that extract and produce multiple metals are an important component of mineral supply. The reaction of such firms to changes in their relevant output prices is tested econometrically for five metals using a panel representing more than 100 mines across the time period 1991-2005. Here, the estimation strategy is drawn from joint production theory, namely a flexible form, dual revenue approach with seemingly unrelated regressions (SUR) estimation. The results indicate that multi-product mines respond (in the short run) to higher prices of a particular metal by reducing output of that metal (indicative of low-grading behavior) and increasing and/or decreasing output of joint metal products (indicative of substitutes and complements in supply). As a result, the price responses are not readily explained by a metal's classification as a by-product or main product based on revenue.

99 GENERAL AND MISCELLANEOUS↗