Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ACCELERATION STRESS”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

HIGH-STRENGTH LIGHTWEIGHT ENGINES FOR HEAVY-DUTY DIESEL TRUCKS

This project with Cummins supports the development of next generation heavy duty diesel engines that can achieve a 50% or better Break Thermal Efficiency (BTE). The fuel efficiency roadmap for the 50% BTE engine considers six main areas for efficiency improvement in the baseline engine, several of which involve making more efficient use of thermal energy (heat) in the engine. Increased operating temperatures and improved thermal management are expected to enable significant increases in $power$ $density$, thus resulting in greater power output for the same sized engine or engine downsizing (or light weighting) for the same power output. However, it has become apparent that several key components will be exposed to temperatures beyond the capabilities of current engine and exhaust materials, requiring the availability of the next generation of high temperature materials to allow the engine to reach the targeted efficiencies, commercially viable durability, and emission targets. The objective of this project was to identify and/or develop key materials, and evaluate their critical properties to enable the design and development of a lightweight, higher efficiency engine, with enhanced temperature capability and reduced heat-loss to the atmosphere in order to facilitate waste heat recovery and improved efficiency. An increase in the temperature capability of exhaust manifold materials, and piston materials were identified as having a positive influence on the efficiency of the next generation diesel engines. Since the current materials (High SiMo cast irons used in exhaust manifolds, and 4140 steel in pistons) are already operating near their limits of their temperature and strength capabilities, it was determined that new materials with the right combination of properties are required for these components. Oxidation and constrained thermal fatigue tests were used to down-select CF8C plus (CF8CP), a cast austenitic stainless steel, for exhaust manifolds capable of operating at higher temperatures. A prototype exhaust manifold was fabricated using CF8CP and successfully tested in a marine engine. A functionally graded multiple-layer thermal barrier coating system was designed with four layers of mixed bondcoat alloy (NiCoCrAlYHfSi) and yttria stabilized zirconia (YSZ) and was shown to reduce the effective thermal conductivity of the coating-substrate (steel and Ti-6Al-4V) system. The graded alloy and YSZ mixture were intended to achieve better match of thermal expansion coefficient (CTE) and minimize thermal stresses. Such coatings can increase the temperature capability of pistons fabricated from steel and Ti-alloys. Effect of oil additives and friction conformal contact friction tests showed there was a 15-30% reduction in friction by the polymer-graphite composite coating compared to the uncoated steel piston. Standalone Mn-P coating had little beneficial impact. Changing the oil from CJ-4 to PC-11 had little impact on the friction behavior in boundary lubrication. Wear behavior was tested under a point contact configuration with a high contact pressure. The candidate CK-4 oil showed similar or slightly better lubricity compared to the CJ-4 oil while the candidate FA-4 oil decisively increased the piston skirt wear. Although both coatings prevented scuffing failure observed for the uncoated steel skirt in a base oil without an additive package, they surprisingly caused a higher piston wear rate when tested in any of the fully formulated engine oil. The detrimental impact was attributed to the Mn-P film, either as a standalone coating, or a coating interlayer. The porous and brittle Mn-P film was broken during the wear test and the released hard Mn-P grains are suspected to cause third-body abrasion to accelerate the wear process. This work also evaluated the feasibility of developing an improved high temperature, low mass, cost-neutral turbocharger compressor wheel for heavy-duty engine applications from TiAl using additive manufacturing, utilizing its unique ability to fabricate high strength, low weight structures. This work has shown that the phase transforming nature of the TiAl alloys enable obtaining equiaxed microstructures in the as-built state without the need for tedious beam parameter manipulations. The HIPed structures have good RT tensile properties that will enable them to be surface machined to the required tolerance that can 2 then be heat treated to obtain the desired microstructures. Additionally, the negligible residual stresses stemming from the high build chamber temperatures ensure the parts are formed without cracks (one of the major issues in traditional manufacturing of these intermetallics).

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS2001

Effects of via-conductor geometry in the electromigration failure of Al:Cu wires

Electromigration (EM) experiments conducted using two types of via/plug to conductor alignment indicate a geometrical dependence of electromigration failure in Al:Cu conductors. The resistance vs time curves show distinctive steps when the alignment is parallel. This is explained by a successive loss of conductivity through the plug due to void formation. In the perpendicular via/conductor arrangement, resistance increases by smaller and closely spaced steps. EM experiments without vias, found that the conductor life under stress increases by at least an order of magnitude. Kinetic studies at four temperatures between 180-240 C found activation energies to be 1.0 plus or minus 0.1eV.

Al:Cu accelerated testing electromigration activat↗
DOE OSTI2023

An Initial Look at the Magnetic Design of a 150 mm Aperture High-Temperature Superconducting Magnet With a Dipole Field of 8 to 10 T

High-temperature superconducting REBa 2 Cu 3 O 7-$x$ (rebco) conductors have the potential to generate a high magnetic field over a broad temperature range. The corresponding accelerator magnet technology, still in its infancy, can be attractive for future energy-frontier particle colliders such as a multi-TeV muon collider. To help develop the technology, we explore the requirements and potential characteristics of a rebco magnet, operating at 4.2 or 20 K, with a dipole field of 8-10 T in a clear aperture of 150 mm. We use the canted cos $\theta$ magnet configuration to reduce the electromagnetic stresses on the conductors. We present the resulting dipole fields, field gradients for combined-function cases, conductor stresses, magnet dimensions and conductor lengths. We also discuss the conductor performance that is required to achieve the target dipole field at 4.2 and 20 K. In conclusion, the information can provide useful input to the development of rebco magnet and conductor technology for collider-ring magnets in a muon collider.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Unraveling fundamental mechanisms of silicon nitride crystallization in microelectronics manufacturing

This research project investigates the fundamental mechanisms of silicon nitride (SiN) crystallization, aiming to enhance the understanding of this critical material in microelectronics manufacturing. Through a collaborative effort between Sandia National Laboratories, the University of Tennessee, and the University of Florida, we developed a comprehensive framework that integrates experimental techniques, atomistic modeling, meso-scale simulations, and an integrated multi-scale model to capture this physical phenomenon on multiple time and length scales . The project developed a new machine learning based atomistic potential and utilized advanced phase field modeling to capture the complexities of polycrystalline growth and the influence of mechanical stresses on crystallization dynamics. By employing a grain tracker algorithm, the meso-scale model effectively identified and tracked individual crystal grains, enabling the simulation of anisotropic growth behaviors reflective of SiN’s physical properties. The integration of atomistic simulations with meso-scale modeling created a powerful multi-scale framework that validated atomistic inputs and enhanced predictive accuracy for crystallization dynamics at larger scales, validated experimentally. This adaptable modeling capability not only accelerates development times by informing manufacturing processes but also serves as a valuable starting point for understanding crystallization physics in similar materials. The insights gained from this research unlock new opportunities for the development of advanced materials tailored for future microelectronics and photonics applications. Overall, this project represents a significant advancement in understanding of fundamental physics of SiN and establishes a foundation for future research in material science, bridging the gap between atomic-level phenomena and macroscopic material behaviors for practical applications.

36 MATERIALS SCIENCE↗
NASA NTRS1990

The Hubble Space Telescope

The Hubble Space Telescope was launched from the Kennedy Space Center on April 24, 1990. Its initial check-out indicates that all sub-systems of the satellite are working very well, with two key exceptions: The line-of-sight pointing is subject to occasional jitter apparently induced by thermal stresses in the solar arrays; this is expected to be overcome. The telescope mirrors are found to contain approximately 0.5 wave rms of spherical aberration which cannot be overcome by any controls on board the satellite. This defect will limit the scientific performance of the telescope in the short run. However, the aberration can be fully corrected in the optical designs of future replacement instruments, and the delivery schedules of these instruments are being accelerated.

Boggess, Albert↗
NASA NTRS1997

The endomembrane sheath: a key structure for understanding the plant cell?

Recent evidence suggests that integrin is abundant in endomembranes of plant cells, and the endomembranes are clad by a sheath of cytoskeleton including F-actin. A role for endomembrane integrin and the endomembrane sheath is proposed: this system might orchestrate metabolic regulation by providing and modulating loci for channelling, and might accelerate channeling as needed by dragging the endoplasmic reticulum (ER) and organelles through the cytoplasm. To accomplish this "streaming", F-actin might lever against the rest of the endomembrane sheath and the ER might also lever against adhesion sites (i.e., plasmodesmata and plasmalemmal control centers). As an important agent in the control of cellular activities, according to this model, the endomembrane sheath would play a major part in responses to diverse signals and stresses, and under extreme stress cell survival would depend on the ability of the system to maintain enough integrity to direct critical syntheses and degradations.

NASA Discipline Plant Biology↗
NASA NTRS2016

A Telescopic and Microscopic Examination of Acceleration in the June 2015 Geomagnetic Storm: Magnetospheric Multiscale and Van Allen Probes Study of Substorm Particle Injection

An active storm period in June 2015 showed that particle injection events seen sequentially by the four (MagnetosphericMultiscale) MMS spacecraft subsequently fed the enhancement of the outer radiation belt observed by Van Allen Probes mission sensors. Several episodes of significant southward interplanetary magnetic field along with a period of high solar wind speed (Vsw 500kms) on 22 June occurred following strong interplanetary shock wave impacts on the magnetosphere. Key events on 22 June 2015 show that the magnetosphere progressed through a sequence of energy-loading and stress-developing states until the entire system suddenly reconfigured at 19:32 UT. Energetic electrons, plasma, and magnetic fields measured by the four MMS spacecraft revealed clear dipolarization front characteristics. It was seen that magnetospheric substorm activity provided a seed electron population as observed by MMS particle sensors as multiple injections and related enhancements in electron flux.

Baker, D. N.↗
DOE OSTI2017

RECONNECTION-DRIVEN CORONAL-HOLE JETS WITH GRAVITY AND SOLAR WIND

Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry, gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfvén wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfvén waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Revealing structure and shaping priorities in plant and fungal cell wall architecture via solid-state NMR

Plant and fungal cell walls are essential for growth, adaptation, and survival, with their intricate architectures dictating both resistance to stress and susceptibility to antifungal or biomass-degrading strategies. Understanding how these walls are built, remodeled, and function at the molecular level is therefore central to both clinical and biotechnological applications. Solid-state nuclear magnetic resonance (ssNMR) has emerged as a uniquely powerful tool for this purpose, as it reveals the structure, dynamics, and interactions of intact biopolymers without disrupting their native organization. Using this approach, recent studies have shown how structural polymorphism, polymer-polymer interactions, and species-specific remodeling govern mechanical integrity, drug resistance, and stress adaptation. Applications highlighted here include lignin-carbohydrate packing during plant stem maturation, fungal wall reorganization under treatment by wall-targeting antifungals such as echinocandin and nikkomycin, and the functional diversity of glucans, chitins, and mannans. Together, these insights uncover conserved principles of polymer assembly across kingdoms while informing new opportunities for antifungal development and biomass utilization. Ongoing advances in sensitivity and resolution are expected to broaden the reach of ssNMR and further accelerate its role in linking structural heterogeneity to biosynthetic complexity and biological function.

Antifungal↗
DOE OSTI2018

Investigation of the Impact of Illumination on the Polarization-Type Potential-Induced Degradation of Crystalline Silicon Photovoltaic Modules

Accelerated potential-induced degradation (PID) testing of photovoltaic modules is conventionally conducted in the dark and at high temperature and humidity levels without considering the influence of illumination. This study investigates the impact of illumination on the polarization-type PID (PID-p) on two different types of encapsulated (glass/backsheet) crystalline silicon solar cells: 1) n-type bifacial passivated emitter rear totally diffused (the front side is facing glass and PID-stressed); and 2) p-type bifacial passivated emitter and rear cell (the rear side is facing glass and PID-stressed). The samples are stressed under the conditions of -1000 V, 40 degrees C, and 40% relative humidity and at different irradiance levels (xenon lamps). While the type-A modules show no reduction in PID-p sensitivity under illumination up to 800 W/m 2 , PID-p in the type-B modules is arrested by the light at an irradiance level as low as 10 W/m 2 . Furthermore, PID-degraded type-B modules (degradation induced in the dark) exhibit a rapid recovery (full recovery in 20 min) upon exposure to light (40 W/m 2 ). External quantum efficiency measurements on the type-B modules show that ultraviolet from 300 to 400 nm is mainly responsible for the fast recovery.

14 SOLAR ENERGY↗
DOE OSTI2021

Morphogene-assisted transformation of Sorghum bicolor allows more efficient genome editing

Sorghum bicolor (L.) Moench, the fifth most important cereal worldwide, is a multi-use crop for feed, food, forage and fuel. To enhance the sorghum and other important crop plants, establishing gene function is essential for their improvement. For sorghum, identifying genes associated with its notable abiotic stress tolerances requires a detailed molecular understanding of the genes associated with those traits. The limits of this knowledge became evident from our earlier in-depth sorghum transcriptome study showing that over 40% of its transcriptome had not been annotated. Here, we describe a full spectrum of tools to engineer, edit, annotate and characterize sorghum’s genes. Efforts to develop those tools began with a morphogene-assisted transformation (MAT) method that led to accelerated transformation times, nearly half the time required with classical callus-based, non-MAT approaches. These efforts also led to expanded numbers of amenable genotypes, including several not previously transformed or historically recalcitrant. Another transformation advance, termed altruistic, involved introducing a gene of interest in a separate Agrobacterium strain from the one with morphogenes, leading to plants with the gene of interest but without morphogenes. The MAT approach was also successfully used to edit a target exemplary gene, phytoene desaturase. To identify single-copy transformed plants, we adapted a high-throughput technique and also developed a novel method to determine transgene independent integration. These efforts led to an efficient method to determine gene function, expediting research in numerous genotypes of this widely grown, multi-use crop.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

A Compact Gas Liquid Separator for the Spallation Neutron Source Mercury Process Loop

Upgrades at the spallation neutron source (SNS) accelerator at Oak Ridge National Laboratory are underway to double its proton beam power from 1.4 to 2.8 MW. About 2 MW will go to the current first station while the rest will go to the future Second Target Station. The increase of beam power to the first target station is especially challenging for its mercury target. When the short proton beam hits the target, strong pressure waves are generated, causing cavitation erosion and challenging stresses for the target's weld regions. SNS has successfully operated reliably at 1.4 MW by mitigating the pressure wave with the injection of small Helium bubbles into the mercury. To operate reliably at 2 MW, more gas will be injected into mercury to mitigate the pressure wave further. However, the mercury process loop was not originally designed for gas injection, and the accumulation of gas in the pipes is a concern. Due to space constraints, a custom gas liquid separator (GLS) was designed to fit a 90-deg horizontal elbow space in the SNS mercury loop. Simulations and experiments were performed, and a successful design was developed that has the desired efficiency while keeping the pressure losses acceptable.

42 ENGINEERING↗
DOE OSTI2017

Coupled Thermo-Mechanical and Photo-Chemical Degradation Mechanisms that determine the Reliability and Operational Lifetimes for CPV Technologies

This project sought to identify and characterize the coupled intrinsic photo-chemo-mechanical degradation mechanisms that determine the reliability and operational lifetimes for CPV technologies. Over a three year period, we have completed a highly successful program which has developed quantitative metrologies and detailed physics-based degradation models, providing new insight into the fundamental reliability physics necessary for improving materials, creating accelerated testing protocols, and producing more accurate lifetime predictions. The tasks for the program were separated into two focus areas shown in the figure below. Focus Area 1, led by Reinhold Dauskardt and Warren Cai with a primary collaboration with David Miller of NREL, studied the degradation mechanisms present in encapsulant materials. Focus Area 2, led by Reinhold Dauskardt and Ryan Brock with a primary collaboration with James Ermer and Peter Hebert of Spectrolab, studied stress development and degradation within internal CPV device interfaces. Each focus area was productive, leading to several publications, including findings on the degradation of silicone encapsulant under terrestrial UV, a model for photodegradation of silicone encapsulant adhesion, quantification and process tuning of antireflective layers on CPV, and discovery of a thermal cycling degradation mechanism present in metal gridline structures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

FY25 Status Update on A709 Code Case Testing at ANL

This report provides an update on the status of the creep rupture testing on the precipitation-treated (PT) Alloy 709 samples fabricated from the first, the second and the third commercial heats, in support of the first, 100,000-hour Alloy 709 Code Case development under the American Society of Mechanical Engineers (ASME) Section III, Division 5 for high-temperature reactor construction. In Fiscal Year (FY) 25, no new tests were initiated, while 5 previously loaded tests were completed. This report presents an overview of the creep-rupture data gathered at Argonne National Laboratory (ANL) since FY21 that totaled 52 completed tests. Metallographic images showing crack morphologies in some representative samples ruptured in FY25 are also included. Key conclusions include: 1) the creep behavior of the three heats of Alloy 709 can be well described by the Larson-Miller relationship; 2) higher temperatures and larger stresses lead to shorter creep life and higher minimum creep rate; 3) Alloy 709 is overall very ductile under creep; 4) the crack morphologies near fracture surfaces are dependent on material’s grain size and test conditions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1980

The influence of a high pressure gradient on unsteady velocity perturbations in the case of a turbulent supersonic flow

The amplification or reduction of unsteady velocity perturbations under the influence of strong flow acceleration or deceleration was studied. Supersonic flows with large velocity, pressure gradients, and the conditions in which the velocity fluctuations depend on the action of the average gradients of pressure and velocity rather than turbulence, are described. Results are analyzed statistically and interpreted as a return to laminar process. It is shown that this return to laminar implies negative values in the turbulence production terms for kinetic energy. A simple geometrical representation of the Reynolds stress production is given.

Dussauge, J. P.↗
NASA NTRS1981

Turbulence and stress owing to gravity wave and tidal breakdown

For some years it has been accepted that tides and gravity waves propagating into the upper mesosphere from below are the major source of turbulence in the upper mesosphere. The considered investigation has the objective to examine the implications of such a situation in some detail. The main propagating diurnal mode seems to be the primary contributor at tropical latitudes. Because of the high phase speed of this mode, it is only slightly affected by the mean zonal flow of the atmosphere. Wavebreaking appears to occur around 85 km, leading to a layer of enhanced eddy diffusion and wave induced acceleration extending between 85 km and about 108 km. Above 108 km molecular transport dominates. Gravity waves appear to be dominant at middle and high latitudes. The flow distribution will effectively determine which gravity waves (depending on phase speed) can reach the mesosphere.

Lindzen, R. S.↗
DOE OSTI2016

On sorption and swelling of CO 2 in clays

One well-studied technology is the geological storage of carbon dioxide (CO 2 ), and a number of demonstration projects around the world have proven its feasibility and challenges. Storage conformance and seal integrity are among the most important aspects, as they determine risk of leakage as well as limits for storage capacity and injectivity. By providing evidence for safe storage is critical for improving public acceptance. Most caprocks are composed of clays as dominant mineral type which can typically be illite, kaolinite, chlorite or smectite. A number of recent studies addressed the interaction between CO 2 and these different clays and it was shown that clay minerals adsorb considerable quantities of CO 2 . For smectite this uptake can lead to volumetric expansion followed by the generation of swelling pressures. On the one hand CO 2 adsorption traps CO 2 , on the other hand swelling pressures can potentially change local stress regimes and in unfavourable situations shear-type failure is assumed to occur. Moreover, for storage in a reservoir having high clay contents the CO 2 uptake can add to storage capacity which is widely underestimated so far. Smectite-rich seals in direct contact with a dry CO 2 plume at the interface to the reservoir might dehydrate leading to dehydration cracks. Such dehydration cracks can provide pathways for CO 2 ingress and further accelerate dewatering and penetration of the seal by supercritical CO 2 . At the same time, swelling may also lead to the closure of fractures or the reduction of fracture apertures, thereby improving seal integrity. Finally, the goal of this communication is to theoretically evaluate and discuss these scenarios in greater detail in terms of phenomenological mechanisms, but also in terms of potential risks or benefits for carbon storage.

58 GEOSCIENCES↗
DOE OSTI2020

Understanding PV Polymer Backsheet Degradation through X-Ray Scattering

Understanding how photovoltaic (PV) module backsheet polymers age and degrade in response to environmental stresses is important for designing polymers that can maintain their structural integrity after decades of outdoor use. X-ray scattering is a powerful technique for exploring backsheet polymer structure at the angstrom- (wide-angle, WAXS) and nanometer- (small-angle, SAXS) length-scales. We present the use of SAXS and WAXS to study pristine and aged polymer backsheets. The structural insight from these techniques can be used to compare the degradation induced by accelerated testing with the degradation seen in field-aged PV materials.

14 SOLAR ENERGY↗