Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Strain engineering”

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 1,747 records · Page 97
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Strain Field Analysis in Electronic Components by ESPI: Bad Thermal Contact and Damage Evaluation

Designing electronic components and devices is a complex task that must include also considerations about thermo-mechanical behavior of the component itself. This aspect, in fact, can affect the reliability of the device as a consequence of the thermal stresses that are introduced in the component while it is working. Stress concentration can arise, in fact, due to different thermal expansion coefficients of the materials involved. Determining the thermo-mechanical response by numerically methods is not simple and not always possible so that experimental methods are preferable. In this paper, specifically, the electronic speckle pattern interferometry technique was adopted to measure full-field strain of the component during exercise. By using an optical technique it is possible to get information about the behavior of the component without being in contact with the component itself so that the dissipation coefficient is not altered. The system was able to detect gradients of deformation in the component itself connected to the different distribution of internal current in the component. Moreover, it was observed, that the presence of bad thermal contact between the package and the heat sink can be revealed because it results in a different thermos-mechanical behavior of the component. Finally, a critical defect was introduced in the component and it was observed the way the presence of damage affects the in-plane displacement of the component. Very huge differences were observed leading to the consideration that this kind of approach could be conveniently adopted also as a damage detection tool.

42 ENGINEERING↗
DOE OSTI2022

Refinements for Bragg coherent X-ray diffraction imaging: electron backscatter diffraction alignment and strain field computation

Bragg coherent X-ray diffraction imaging (BCDI) allows the 3D measurement of lattice strain along the scattering vector for specific microcrystals. If at least three linearly independent reflections are measured, the 3D variation of the full lattice strain tensor within the microcrystal can be recovered. However, this requires knowledge of the crystal orientation, which is typically attained via estimates based on crystal geometry or synchrotron microbeam Laue diffraction measurements. Presented here is an alternative method to determine the crystal orientation for BCDI measurements using electron backscatter diffraction (EBSD) to align Fe–Ni and Co–Fe alloy microcrystals on three different substrates. The orientation matrix is calculated from EBSD Euler angles and compared with the orientation determined using microbeam Laue diffraction. The average angular mismatch between the orientation matrices is less than ∼6°, which is reasonable for the search for Bragg reflections. The use of an orientation matrix derived from EBSD is demonstrated to align and measure five reflections for a single Fe–Ni microcrystal via multi-reflection BCDI. Using this data set, a refined strain field computation based on the gradient of the complex exponential of the phase is developed. This approach is shown to increase accuracy, especially in the presence of dislocations. The results demonstrate the feasibility of using EBSD to pre-align BCDI samples and the application of more efficient approaches to determine the full lattice strain tensor with greater accuracy.

42 ENGINEERING↗
DOE OSTI2024

Strain shift measured from stress-controlled oscillatory shear: Evidence for a continuous yielding transition and new techniques to determine recovery rheology measures

Understanding the yielding of complex fluids is an important rheological challenge that affects our ability to engineer and process materials for a wide variety of applications. Common theoretical understandings of yield stress fluids follow the Oldroyd–Prager formalism in which the material behavior below the yield stress is treated as solidlike, and above the yield stress as liquidlike, with an instantaneous transition between the two states. This formalism was built on a quasi-static approach to the yield stress, while most applications, ranging from material processing to end user applications, involve a transient approach to yielding over a finite timescale. Using stress-controlled oscillatory shear experiments, we show that yield stress fluids flow below their yield stresses. This is quantified through measuring the strain shift, which is the value about which the strain oscillates during a stress-controlled test and is a function of only the unrecoverable strain. Measurements of the strain shift are, therefore, measurements of flow having taken place. These experimental results are compared to the Herschel–Bulkley form of the Saramito model, which utilizes the Oldroyd–Prager formalism, and the recently published Kamani–Donley–Rogers (KDR) model, in which one constitutive equation represents the entire range of material responses. Scaling relationships are derived, which allow us to show why yield stress fluids will flow across all stresses, above and below their yield stress. Finally, derivations are presented that show strain shift can be used to determine average metrics previously attainable only through recovery rheology, and these are experimentally verified.

Mechanics↗
NASA NTRS2008

Full-field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites

Composite materials made with triaxial braid architecture and large tow size carbon fibers are beginning to be used in many applications, including composite aircraft and engine structures. Recent advancements in braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape. Although the large unit cell size of these materials is an advantage for manufacturing efficiency, the fiber architecture presents some challenges for materials characterization, design, and analysis. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A potential problem with using standard tests methods for these materials is that the unit cell size can be an unacceptably large fraction of the specimen dimensions. More detailed investigation of deformation and failure processes in large unit cell size triaxial braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. In recent years, commercial equipment has become available that enables digital image correlation to be used on a more routine basis for investigation of full field 3D deformation in materials and structures. In this paper, some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques are presented. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12 and 24 k yarns and a 0/+60/-60 triaxial braid architecture. Local deformation and failure within fiber bundles was observed, and this local failure had a significant effect on global stiffness and strength. The matrix material had a large effect on local damage initiation for the two matrix materials used in this investigation. Premature failure in regions of the unit cell near the edge of the straight-sided specimens was observed for transverse tensile tests in which the braid axial fibers were perpendicular to the specimen axis and the bias fibers terminated on the cut edges in the specimen gage section. This edge effect is one factor that could contribute to a measured strength that is lower than the actual material strength in a structure without edge effects.

Littell, Justin D.↗
DOE OSTI2023

Recent Advances in Picochlorum renovo Strain Development

Microalgae are amongst the most efficient phototrophs for the reduction of CO2 to industrially relevant products and product intermediates. We have recently identified a novel species in the genus Picochlorum (Picochlorum renovo) that demonstrates high areal productivity (>30 g/m2/day), high temperature and salinity tolerances, and rapid growth rate (-2 hour doubling time): attributes essential for economically viable industrial scale deployment for low value commodities (e.g. fuel and chemical precursors). Following screening of >300 algal isolates to identify Picochlorum renovo, we developed baseline genetic tools necessary for genetic engineering of the nucleus and chloroplast, and further built upon these tools to establish a protein secretion system. We have also deployed genetic engineering tools to establish the utilization of phosphite as a selectable marker in the chloroplast and nuclear genomes, while concurrently acting as a potential crop protection strategy. We have further implemented these tools to enable the utilization of formate as a novel carbon source for phototroph cultivation. Explicitly, formate toxicity was assayed, followed by introduction of a formate dehydrogenase to allow formate utilization. Cultures supplemented with formate grew to a higher density when cultivated under ambient CO2, highlighting the potential for this strategy to increase growth. Additionally, we have established a synthetic transcription factor and core promoter system which lays the foundation for tunable, high expression engineering in the nuclear genome, and potentially can be applied for universal algal genetic engineering. Finally, current work has focused on direct photosynthetic production of chemicals, and generation of mutant libraries. Combined, our work has established a robust genetic toolbox for Picochlorum renovo, which we have deployed for strain development purposes to introduce biotechnologically relevant traits.

algae↗
DOE OSTI2018

Investigation into the Development and Testing of a Simplex Capacitance Sensor for Rotor Tip Clearance Measurement in Turbo Machinery

The rotor tip clearance is a vital parameter to characterize turbomachinery performance. It is an essential measurement during engine development and testing. The efficiency of the major modules like fan, compressor and turbine depends on the optimum running clearances. The capacitive sensor is preferred for tip clearance measurements because of various inherent advantages. They are fabricated through complex processes for turbomachinery application and are expensive. These sensors are exposed to harsh engine environments and are likely to exhibit degraded performance. Insulation failure at sensing head, connector contamination and micro-cracks in the MI (Mineral Insulated) cable leads to noise in the signal output. Frequent mechanical failures are also seen due to work hardening of MI cables, lead connector detachments and failure of micro fins at interconnects. Fault fixing of these is tedious and very expensive. This paper presents the concerted effort in developing a simple capacitance sensor addressing potential sensor failure issues. The design features include simple construction, ease of sensor assembly, component realization and troubleshooting. The design also addresses all safety requirements. The sensor has a large sensing area (7.6 mm diameter) producing very stable, high-level signal. The developed sensor produces output that varies from 1 V{sub P-P} to 11 V{sub P-P} for blade-tip gaps between 3 mm to 0.4 mm respectively. Blade pass simulation studies across the sensor, display almost flat response at minimum clearance. This feature results in very minimal data acquisition errors. The sensor along with RC (Resistance-Capacitance) conditioning electronics was successfully used for clearance measurement on fan stage of gas turbine engine. Test results are in line with the predictions. Extensive tip clearance measurements on the engine validate the design. The current work provides an insight into the development of a simplex capacitance sensor for tip clearance measurement.

42 ENGINEERING↗
DOE OSTI2018

Dynamic Tensile Experimental Techniques for Geomaterials: A Comprehensive Review

Here, this review article is dedicated to the Dynamic Behavior of Materials Technical Division for celebrating the 75th anniversary of the Society for Experimental Mechanics (SEM). Understanding dynamic behavior of geomaterials is critical for analyzing and solving engineering problems of various applications related to underground explosions, seismic, airblast, and penetration events. Determining the dynamic tensile response of geomaterials has been a great challenge in experiments due to the nature of relatively low tensile strength and high brittleness. Various experimental approaches have been made in the past century, especially in the most recent half century, to understand the dynamic behavior of geomaterials in tension. In this review paper, we summarized the dynamic tensile experimental techniques for geomaterials that have been developed. The major dynamic tensile experimental techniques include dynamic direct tension, dynamic split tension, and spall tension. All three of the experimental techniques are based on Hopkinson or split Hopkinson (also known as Kolsky) bar techniques and principles. Finally, uniqueness and limitations for each experimental technique are also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Mutation of the dengue virus type 2 envelope protein heparan sulfate binding sites or the domain III lateral ridge blocks replication in Vero cells prior to membrane fusion

Using an infectious cDNA clone we engineered seven mutations in the putative heparan sulfate- and receptor-binding motifs of the envelope protein of dengue virus serotype 2, strain 16681. Four mutant viruses, KK122/123EE, E202K, G304K, and KKK305/307/310EEE, were recovered following transfection of C6/36 cells. A fifth mutant, KK291/295EE, was recovered from C6/36 cells with a compensatory E295V mutation. All mutants grew in and mediated fusion of virus-infected C6/36 cells, but three of the mutants, KK122/123EE, E202K, G304K, did not grow in Vero cells without further modification. Two Vero cell lethal mutants, KK291/295EV and KKK307/307/310EEE, failed to replicate in DC-SIGN-transformed Raji cells and did not react with monoclonal antibodies known to block DENV attachment to Vero cells. Additionally, both mutants were unable to initiate negative-strand vRNA synthesis in Vero cells by 72 h post-infection, suggesting that the replication block occurred prior to virus-mediated membrane fusion. - Highlights: • Heparan sulfate- and receptor-binding motifs of DENV2 envelope protein were mutated. • Four mutant viruses were isolated—all could fuse C6/36 cells. • Two of these mutants were lethal in Vero cells without further modification. • Lethal mutations were KK291/295EV and KKK305/307/310EEE. • Cell attachment was implicated as the replication block for both mutants.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Final Report for Project 13-4791: New Mechanistic Models of Creep-Fatigue Crack Growth Interactions for Advanced High Temperature Reactor Components

This project developed and validated a novel, multi-scale, mechanism-based model to quantitatively predict creep-fatigue crack growth and failure for Ni-based Alloy 617 at 800°C. Alloy 617 is a target material for intermediate heat exchangers in Generation IV very high temperature reactor designs, and it is envisioned that this model will aid in the design of safe, long lasting nuclear power plants. The technical effectiveness of the model was shown by demonstrating that experimentally observed crack growth rates can be predicted under both steady state and overload crack growth conditions. Feasibility was considered by incorporating our model into a commercially available finite element method code, ABAQUS, that is commonly used by design engineers. While the focus of the project was specifically on an alloy targeted for Generation IV nuclear reactors, the benefits to the public are expected to be wide reaching. Indeed, creep-fatigue failure is a design consideration for a wide range of high temperature mechanical systems that rely on Ni-based alloys, including industrial gas power turbines, advanced ultra-super critical steam turbines, and aerospace turbine engines. It is envisioned that this new model can be adapted to a wide range of engineering applications.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Temperature-Dependent Sn Incorporation and Defect Formation in Pseudomorphic SiSn Layers on Si (001) via Molecular Beam Epitaxy

SiSn alloys have attracted growing interest for group-IV bandgap engineering, although their epitaxial growth remains challenging due to the extremely low equilibrium solubility of Sn in Si. In this work, fully strained (pseudomorphic) SiSn epitaxial layers were grown on Si (001) substrates by means of molecular beam epitaxy. A systematic investigation reveals a strong inverse correlation between growth temperature and Sn incorporation efficiency. Despite a constant Sn flux, the incorporated Sn composition decreases from 5.5% to 3.2% as the growth temperature increases, indicating a pronounced temperature dependence of Sn incorporation. Reflection high-energy electron diffraction indicates a gradual transition of the growth from two-dimensional to three-dimensional with increasing film thickness. Structural characterization by means of X-ray diffraction, atomic force microscopy, and transmission electron microscopy confirms the pseudomorphic growth and smooth surface morphology and reveals twins and stacking faults near the surface region. These results establish a quantitative reference for SiSn growth kinetics and provide guidance for future studies of SiSn and SiGeSn alloys in silicon-compatible electronic and optoelectronic applications.

SiSn alloys↗
NASA NTRSDate not supplied

An Overview of Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Capabilities, Upgrades, and Overlaps in Advanced Material Testing Areas

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) was designed to perform non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and materials. NTREES can simulate the thermal hydraulic environment within the reactor of an NTR and has been leveraged to provide data on the thermochemical, thermomechanical and thermohydraulic performance of components and materials. Active upgrades to the NTREES facility include installing a DC power supply for DC powered joule heating, a supply gas chiller for a cryogenically cool gas supply, gas pre-heaters with sample holders for testing samples too small to be inductively heated by bathing them in hot gas, and a high temperature digital image correlation (DIC) capability for measuring high temperature strains real time. In addition to NTR testing, given the commonality of high enthalpy flow environments between the reactor of an NTP engine and the aerothermal heating of high-speed flight, the unique capabilities of NTREES to provide high temperature gas flows at high pressure without combustion or electrode spallation byproducts may lend itself to additional usage of the facility beyond the original intent.

Michael P Schoenfeld↗
DOE OSTI2012

Ameliorating risk: Culturable and metagenomic monitoring of the 14 year decline of a genetically engineered microorganism at a bioremediation field site

Pseudomonas fluorescens HK44 represented the first genetically engineered microorganism to be approved in the United States for field release for applications related to subsurface soil bioremediation. In October 1996, strain HK44 was introduced into a replicated semi-contained array of soil lysimeters where its luciferase (luxCDABE)-based bioluminescent response to soil-borne polycyclic aromatic hydrocarbon (PAH) contaminants was detected and monitored for the next two years. At the termination of this experiment, it was decided that the lysimeters remain available for future longer-term monitoring efforts, and were thus covered and left essentially undisturbed until the initiation of a large sampling event in 2010, fourteen years after the original release. Although after extensive sampling culturable HK44 cells were not found, additional molecular and metagenomic analyses indicated that genetic signatures of HK44 cells still persisted, with genes diagnostic for the bioluminescent transposon carried by strain HK44 (luxA and tetA) being found at low concentrations (< 5000 copies/g).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Kinetically Dormant Ni‐Rich Layered Cathode During High‐Voltage Operation

Abstract The degradation of Ni‐rich cathodes during long‐term operation at high voltage has garnered significant attention from both academia and industry. Despite many post‐mortem qualitative structural analyses, precise quantification of their individual and coupling contributions to the overall capacity degradation remains challenging. Here, by leveraging multiscale synchrotron X‐ray probes, electron microscopy, and post‐galvanostatic intermittent titration technique, the thermodynamically irreversible and kinetically reversible capacity loss is successfully deconvoluted in a polycrystalline LiNi 0.83 Mn 0.1 Co 0.07 O 2 cathode during long‐term charge/discharge cycling in full cell configuration. Contradicting the dramatic capacity loss, the layered structure remains highly alive even after 1000 cycles at 4.6 V while undergoing a three‐order of magnitude reduction in the mass transfer kinetics, leading to almost fully recoverable capacity under kinetic‐free conditions. Such kinetic dormant behavior after cycling is not simply ascribed to poor chemical diffusion by reconstructed cathode surface but highly synchronizes with the lattice strain evolution stemming from the structural heterogeneity between deeply delithiated layered and degraded rock‐salt phases at high voltage. These findings deepen the degradation mechanism of high‐voltage cathodes to achieve long‐cycling and fast‐charging performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Recent advancements in the genetic engineering of microalgae

The development of more sustainable food, feed, and bio-products is critical to mitigating the environmental stresses facing our world today. Algae, which includes seaweeds, eukaryotic microalgae, and cyanobacteria, are a promising platform to achieving this, as they have low energy and space requirements, are safe for human and animal consumption, and can be manipulated to produce a diversity of valuable bioproducts. This review focuses on microalgae, both eukaryotic and cyanobacteria. In the past, addressing the major challenges of bringing microalgal production systems to an economically viable scale only had a relatively small genetic toolset to work with, in comparison to other microbial systems such as bacteria and yeast. Expanding the molecular tools available for genetic engineering of microalgae will lead to higher product yields, and accelerate the development of new microalgal bioproducts for commercial applications, thereby supporting the shift towards more environmentally friendly products. In this review, we highlight significant advances from recent years on the design of microalgal expression vectors, discovery of genetic regulatory elements (promoters and transcription factors), optimization of transformation methods, and development of new strain improvement techniques, all aimed at advancing microalgae to become a more efficient biomanufacturing platform. We then discuss how these tools have been applied to improving recombinant protein production, and to enhance metabolic pathway engineering.

09 BIOMASS FUELS↗
DOE OSTI2012

Measurement and modeling of strain fields in zirconium hydrides precipitated at a stress concentration

Hydrogen adsorption into zirconium, as a result of corrosion in aqueous environments, leads to the precipitation of a secondary brittle hydride phase. These hydrides tend to first form at stress concentrations such as fretting flaws or cracks in engineering components, potentially degrading the structural integrity of the component. One mechanism for component failure is a slow crack growth mechanism known as Delayed Hydride Cracking (DHC), where hydride fracture occurs followed by crack arrest in the ductile zirconium matrix. The current work employs both an experimental and a modeling approach to better characterize the effects and behavior of hydride precipitation at such stress concentrations. Strains around stress concentrations containing hydrides were mapped using High Energy X-ray Diffraction (HEXRD). These studies highlighted important differences in the behavior of the hydride phase and the surrounding zirconium matrix, as well as the strain associated with the precipitation of the hydride. A finite element model was also developed and compared to the X-ray strain mapping results. This model provided greater insight into details that could not be obtained directly from the experimental approaches, as well as providing a framework for future modeling to predict the effects of hydride precipitation under varied conditions.

08 HYDROGEN↗
DOE OSTI2019

Surface Engineering by Simultaneous Action of Multiple External Fields (Final Technical Report)

This research project aims at enabling surface engineering strategies based on the fundamental understanding and predictive modeling of the surface morphological response of solid materials subjected to the combined action of multiple external forces. Surface morphological response to mismatch strain in strained-layer heterostructures also is analyzed. Our research focuses on the surface morphological evolution and stability of electrically conducting (metallic, such as Cu) and semiconducting (such as Si) solids under the simultaneous application of mechanical stresses, electric fields, and temperature gradients. We emphasize on identifying the conditions under which the multiply driven surface morphology is stable and on exploring the complexity of the corresponding various morphologically stable surface patterns. We also emphasize on the driven evolution of nanoscale features aiming at stabilizing and controlling nanoscale patterns on surfaces by their manipulation through simultaneously applied multiple external forces. Specifically, we address systematically the morphological response to the combined action of multiple external forces of bulk solid surfaces, surfaces of thin films grown epitaxially on thick or thin substrates, as well as nanoscale surface features such as coherently strained islands grown epitaxially on substrate surfaces. The research is based on a modeling approach that combines theoretical analyses of surface morphological stability with self-consistent dynamical simulations of surface evolution based on properly parameterized continuum and multiscale surface transport models.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Efficient Simulation of Welding Distortion in Large Structures and Its Reduction by Jig Constraints

Two large construction machinery structures were welded separately with and without jig constraints. The welding distortion of the entire structure was measured by a 3D coordinate measuring system and simulated by elastic FEM using the inherent deformation method. To obtain an accurate inherent deformation, a thermal elastoplastic FE analysis of simple one-side fillet joints with and without jig constraints was performed. Efficient simulation of welding distortion in large structures was accomplished by applying inherent deformation in a localized region, and the effect of jig constraint on the reduction of welding distortion was clarified. The computation of inherent deformation, the weld zone definition and the conversion of inherent deformation into inherent strain were automated. Measured and computed welding distortions in large structures had a good correspondence with respect to both tendency and magnitude. Further investigation of jig configuration was performed for enhanced reduction of welding distortion. Alternative controlling techniques for common welded structures were also addressed.

36 MATERIALS SCIENCE↗