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Results for “Youngs Modulus”

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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Effect of dilution in the cobalt subsystem on phase transitions in rare-earth cobaltites RBaCo{sub 4–x}M{sub x}O{sub 7} (R = Dy–Er, Yb, Y; M = Al, Zn)

We have experimentally studied the structural and elastic characteristics of rare-earth cobaltites RBaCo{sub 4–x}M{sub x}O{sub 7} (R = Dy–Er, Yb, Y), in which cobalt ions are partly substituted by diamagnetic Al or Zn ions. It was found that small substitution of Co{sup 3+} ions by Al{sup 3+} ions in the YbRBaCo{sub 4–x}M{sub x}O{sub 7} system (x = 0.1, 0.2, 0.5) leads to a rapid decrease and smearing of ΔE(T)/E{sub 0} anomalies of the Young’s modulus in the region of the structural phase transition, which is accompanied by increasing hysteresis. Pure rare-earth cobaltites RBaCo{sub 4}O{sub 7} (R = Dy–Er, Y) exhibit a correlation between the room-temperature structure distortion and hysteresis on the ΔE(T)/E{sub 0} curve in a temperature interval of 80–280 K. In Zn-substituted cobaltites RBaCoZn{sub 3}O{sub 7}, both the hysteresis and ΔE(T)/E{sub 0} anomalies disappear, as do low-temperature sound absorption maxima. This behavior is evidence of the suppression of structural and magnetic phase transitions and the retention of only short-range correlations of the order parameter in Zn-substituted samples.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Elastic, magnetic, and magnetoelectric properties of the CaBaCo{sub 4}O{sub 7} multiferroic

The structural, elastic, magnetic, and magnetoelectric properties of the CaBaCo{sub 4}O{sub 7} multiferroic are experimentally studied and compared with the properties of the related YBaCo{sub 4}O{sub 7} cobaltite, where Y{sup 3+} ions substitute for Ca{sup 2+} ions. Unlike the frustrated YBaCo{sub 4}O{sub 7} magnet, the softening of Young’s modulus and the hysteresis in the ΔE(T)/E{sub 0} curve of ferrimagnetic CaBaCo{sub 4}O{sub 7} in the paramagnetic region are weak, and the anomaly during the magnetic transition increases by almost an order of magnitude. This difference can point to different characters of the development of a long-range magnetic order in these two cobaltites. The distortion of the crystal structure that removes the frustrations of exchange interactions is found to correlate with the magnetic behavior of the cobaltites under study. The magnetization curves of the Ca cobaltite have two steps below 15 K, which can point to the presence of a metastable state in a high magnetic field. The study of the longitudinal and transverse magnetoelectric effects in a pulsed magnetic field demonstrates that their magnitudes are maximal near T{sub C} and change their character from linear to quadratic during passage through this temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Hydrogen Desorption from Pentagraphane

Thermally activated hydrogen desorption from pentagraphane is studied by atomistic computer simulation. Pentagraphane is a recently predicted quasi-two-dimensional hydrocarbon compound that represents a pentagraphene single layer, in which both sides are covered with hydrogen and the C–C bonds form a network of adjacent pentagons, whereas the hexagons characteristic of carbon nanostructures are lacking. The effect of hydrogen desorption on the electronic structure, phonon density of states, and Young’s modulus are studied. The temperature dependence of the characteristic desorption time is determined by the molecular-dynamics method.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Phonons, Diffusons, and the Boson Peak in Two-Dimensional Lattices with Random Bonds

Within the model of stable random matrices possessing translational invariance, a two-dimensional (on a square lattice) disordered oscillatory system with random strongly fluctuating bonds is considered. By a numerical analysis of the dynamic structure factor S(q, ω), it is shown that vibrations with frequencies below the Ioffe-Regel frequency ω{sub IR} are ordinary phonons with a linear dispersion law ω(q) ∝ q and a reciprocal lifetime δ~ q{sup 3}. Vibrations with frequencies above ω{sub IR}, although being delocalized, cannot be described by plane waves with a definite dispersion law ω(q). They are characterized by a diffusion structure factor with a reciprocal lifetime δ ~ q{sup 2}, which is typical of a diffusion process. In the literature, they are often referred to as diffusons. It is shown that, as in the three-dimensional model, the boson peak at the frequency ωb in the reduced density of vibrational states g(ω)/ω is on the order of the frequency ω{sub IR}. It is located in the transition region between phonons and diffusons and is proportional to the Young’s modulus of the lattice, ω{sub b}≃E.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Study of the Anisotropic Elastoplastic Properties of β-Ga{sub 2}O{sub 3} Films Synthesized on SiC/Si Substrates

The structural and mechanical properties of gallium oxide films grown on silicon crystallographic planes (001), (011), and (111) with a buffer layer of silicon carbide are investigated. Nanoindentation was used to study the elastoplastic properties of gallium oxide and also to determine the elastic recovery parameter of the films under study. The tensile strength, hardness, elasticity tensor, compliance tensor, Young’s modulus, Poisson’s ratio, and other characteristics of gallium oxide were calculated using quantum chemistry methods. It was found that the gallium oxide crystal is auxetic because, for some stretching directions, the Poisson’s ratio takes on negative values. The calculated values correspond quantitatively to the experimental data. It is concluded that the elastoplastic properties of gallium oxide films approximately correspond to the properties of bulk crystals and that a change in the orientation of the silicon surface leads to a significant change in the orientation of gallium oxide.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Mechanical and Dynamic Stability of Complete and Nonstoichiometric 3C-Si{sub x}C{sub y} from Ab Initio Calculations

The energies of formation of vacancies in the carbon and silicon sublattices, the independent elastic constants, the all-round compression, shear and Young’s moduli, and the anisotropy coefficients are determined for the complete and nonstoichiometric cubic phases of 3C-Si{sub x}C{sub y} (x, y = 1.0–0.75) by ab initio methods of the band theory. In the formalism of the density functional perturbation theory (DFPT), the phonon dispersion dependences are obtained for these phases (the comparison with the experiment is given for the complete phase). It is shown that the mechanical characteristics of the phases become strongly anisotropic upon the transition from 3C-SiC{sub 0.875} to 3C-SiC{sub 0.75}. It is established from the analysis of the phonon dispersion curves that the 3C-SiC{sub 0.875} and 3C-SiC{sub 0.75} phases, in contrast to the complete 3C-SiC phase, are dynamically unstable at T = 0 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Impact of Ultraviolet Irradiation on Stress–Strain Behavior of Syndiotactic 1,2-Polybutadien: The Role of Oxidation

We studied the impact of ultraviolet (UV) irradiation on stress–strain characteristics, derived from uniaxial stretching measurements, and the molecular structure (photoinduced changes) of syndiotactic 1,2-polybutadien, a polymer with thermoplastic elastomer properties. Uniaxial stretching stress–strain curves are recorded for samples subjected to UV irradiation for different times and the effects UV irradiation has on the stress–strain behavior of polymers are analyzed. Long UV irradiation is found to markedly increase the hardening of polymers: Young’s modulus and yield strength increase, while the fracture strain decreases. At the same time, we observe a sharp increase in polymer molecular weight and its considerable oxidation that particularly involves surface layers. The mechanisms of cross-linking between macromolecules and their simultaneous oxidation induced by exposure to UV light are discussed along with the role these processes play in evolution of the physical mechanical properties under UV irradiation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Inelasticity and Nanostructured Dislocation Deformation of Aluminum–Silicon Alloy with a Supermodified Eutectic Structure

Young’s modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Ultrasonic Nondestructive Diagnosis of Cylindrical Batteries Under Various Charging Rates

Lithium-ion batteries have been used increasingly as electrochemical energy storage systems for electronic devices and vehicles. It is important to accurately estimate the state of charge (SoC) of a battery management system to control the battery operation to optimize performance, lifetime, and safety. The current work experimentally leverages ultrasonic diagnostic technology to investigate the SoC of lithium-ion batteries during the charge/discharge processes. A cylindrical-type nickel-cobalt-aluminum (NCA)–based 2500mAh 20A (INR18650-25R) battery was used for ultrasonic measurements with various charge/discharge rates of C/10.4, C/5.2, and C/1.3 at constant currents. The ultrasonic signals were analyzed for extracting wave velocity and wave attenuation. For all the testing rates, wave velocity increased in the charge process and decreased in the discharge process. Further, velocity profiles corresponding to lower rates of C/10.4 and C/5.2 exhibited primary peaks at the maximum SoCs, whereas the absolute wave velocity of C/1.3 rate showed primary peaks that occurred slightly after the SoC peak, indicating a delayed maximum Young's modulus. The wave attenuation computed for the C/10.4 rate had local maxima in the charge and discharge processes and depicted negative correlations with SoC, ranging from 0% to 18%, and positive correlations with SoC from 18% to 85%. On the other hand, the wave attenuation curves of the C/1.3 rate showed no local peaks and had negative correlations with SoC, ranging from 0% to 28%, and positive correlations with SoC ranging from 28% to 53%.

25 ENERGY STORAGE↗
DOE OSTI2014

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li X CoO 2

Mechanical degradation of lithium-ion battery (LIB) electrodes has been correlated with capacity fade and impedance growth over repeated charging and discharging. Knowledge of how the mechanical properties of materials used in LIBs are affected by electrochemical lithiation and delithiation could provide insight into design choices that mitigate mechanical damage and extend device lifetime. Here, we measured Young's modulus E, hardness H, and fracture toughness K Ic via instrumented nanoindentation of the prototypical intercalation cathode, Li X CoO 2 , after varying durations of electrochemical charging. After a single charge cycle, E and H decreased by up to 60%, while K Ic decreased by up to 70%. Microstructural characterization using optical microscopy, Raman spectroscopy, X-ray diffraction, and further nanoindentation showed that this degradation in K Ic was attributable to Li depletion at the material surface and was also correlated with extensive microfracture at grain boundaries. These results indicate that K Ic reduction and irreversible microstructural damage occur during the first cycle of lithium deintercalation from polycrystalline aggregates of Li X CoO 2 , potentially facilitating further crack growth over repeated cycling. Such marked reduction in K Ic over a single charge cycle also yields important implications for the design of electrochemical shock-resistant cathode materials.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Mechanical Degradation of Graphite/PVDF Composite Electrodes: A Model-Experimental Study

Mechanical failure modes of a graphite/polyvinylidene difluoride (PVDF) composite electrode for lithium-ion batteries were investigated by combining realistic stress-stain tests and mathematical model predictions. Samples of PVDF mixed with conductive additive were prepared in a similar way to graphite electrodes and tested while submerged in electrolyte solution. Young's modulus and tensile strength values of wet samples were found to be approximately one-fifth and one-half of those measured for dry samples. Simulations of graphite particles surrounded by binder layers given the measured material property values suggest that the particles are unlikely to experience mechanical damage during cycling, but that the fate of the surrounding composite of PVDF and conductive additive depends completely upon the conditions under which its mechanical properties were obtained. Simulations using realistic property values produced results that were consistent with earlier experimental observations.

25 ENERGY STORAGE↗
DOE OSTI2019

Selective Equatorial Sclera Crosslinking in the Orbit Using a Metal-Coated Polymer Waveguide

Purpose: Photochemical crosslinking of the sclera is an emerging technique that may prevent excessive eye elongation in pathologic myopia by stiffening the scleral tissue. To overcome the challenge of uniform light delivery in an anatomically restricted space, we previously introduced the use of flexible polymer waveguides. We presently demonstrate advanced waveguides that are optimized to deliver light selectively to equatorial sclera in the intact orbit. Methods: Our waveguides consist of a polydimethylsiloxane cladding and a polyurethane core, coupled to an optical fiber. A reflective silver coating deposited on the top and side surfaces of the waveguide prevents light leakage to nontarget, periorbital tissue. Postmortem rabbits were used to test the feasibility of in situ equatorial sclera crosslinking. Tensometry measurements were performed on ex vivo rabbit eyes to confirm a biomechanical stiffening effect. Results: Metal-coated waveguides enabled efficient light delivery to the entire circumference of the equatorial sclera with minimal light leakage to the periorbital tissues. Blue light was delivered to the intact orbit with a coefficient of variation in intensity of 22%, resulting in a 45 ± 11% bleaching of riboflavin fluorescence. A 2-fold increase in the Young's modulus at 5% strain (increase of 92% P < 0.05, at 25 J/cm 2 ) was achieved for ex vivo crosslinked eyes. Conclusions: Flexible polymer waveguides with reflective, biocompatible surfaces are useful for sclera crosslinking to achieve targeted light delivery. We anticipate that our demonstrated procedure will be applicable to sclera crosslinking in live animal models and, potentially, humans in vivo.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Epoxy resin reinforced with carbonized chicken feathers: An innovative composite material with sustainable potentials

Here, this article explores a novel method for enhancing the mechanical properties of epoxy resin composites by incorporating carbonized chicken feathers as a filler material. The fabrication process involves carbonizing chicken feathers at 600°C and incorporating 5-10 wt% of the fillers into an epoxy matrix. The composites showed enhanced mechanical properties and samples containing 10 wt% filler exhibit the best properties. The performance corresponds to 49% increase in tensile strength, 16% rise in Young’s modulus, 40% improvement in flexural modulus, and 57% in flexural strength. X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy were employed to characterize the filler. This characterization provides valuable insights into the structure and chemical composition of the pulverized carbonized chicken feathers that contributed to the attained improvement in composites’ properties. Microstructural examination of the developed composite under scanning electron microscope also provides insights into matrix-filler interface and dispersion of the fillers within the composite matrix. The study not only highlights the unique combination of carbonized feathers’ inherent strength and compatibility with the epoxy matrix but also underscores the eco-friendly nature of utilizing agricultural waste. The findings suggest promising applications in industries demanding lightweight, high-strength materials, which can contribute to sustainable engineering solutions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Quadri-joint inversion: Method and application to the Big Sky 9C 3D data set in northern Montana

The Kevin Dome [Formula: see text] storage project, located in northern Montana, attempted to characterize the Duperow Formation as a potential long-term storage zone for injected [Formula: see text]. A multicomponent (9C) seismic survey was acquired for the Big Sky Carbon Sequestration Partnership over a portion of the Kevin Dome using P- and S-wave sources. Prestack migrated PP, PS, SH, and SV data sets were generated. We then applied several stratigraphic inversion workflows using one or several kinds of seismic wavefield at the same time resulting in joint inversions of each data set. The aim of our study is to demonstrate the benefits of doing quadri-joint inversion of PP-, PS-, SH-, and SV-wavefields for the recovery of the elastic earth parameters, especially the S-wave impedance and density. These are crucial parameters because they can help determine lithology and porefill in the reservoir characterization workflow. Because the inversion workflow always uses the original seismic data recorded in its own time domain, it is necessary to compute registration laws between PP-PS-, PP-SH-, and PP-SV-wavefields using a time shift computation procedure (warping) based on inverted S-wave impedances from inversion of a single wavefield. This generated a significant improvement over methods that rely on attempting to match trace waveforms that may have a different phase, frequency content, and polarity. Finally, we wanted to investigate the reliability of the quadri-joint inversion results in the Bakken/Banff Formations, which have less lateral geologic variation than the underlying Duperow target. This interval shares many of the geophysical characterization challenges common to shale reservoirs in other North American basins. We computed geomechanical parameters, such as Poisson’s ratio and Young’s modulus, which are a proxy for brittleness. Comparison of these results with independent laboratory measurements in the Bakken interval demonstrates the superiority of the quadri-joint inversion method to the traditional inversion using P-wave data only.

Geochemistry & Geophysics↗
DOE OSTI2023

Simulation of Mechanical Fractionation of Chopped Whole-Plant Corn (WPC) Using Discrete Element Method (DEM)

Fractionating whole-plant corn (WPC) in a single-pass harvesting system requires studies on the WPC-to-equipment interaction for improved property control, as well as mechanical and air-driven separation processes compared to the traditional multi-pass grain and stover harvesting system. The discrete element method (DEM) technique has the potential to simulate WPC mechanical fractionation and support simulation-based design of WPC separation processes. In this study, methods to develop DEM particle models of WPC (kernel, cob, stalk, and husk) and their material properties for simulating mass fractionation using the ASABE standard mechanical shaker were proposed. Measurement was done on the axial dimensions (major, intermediate, and minor) and mass of each WPC type (mean sample size is 56), sampled from single-pass harvesting. Applying gaussian multivariate regression and bootstrapping re-sampling techniques, a DEM particle approximate to each WPC was developed. Sensitivity analysis of the DEM Young‘s modulus, Poisson‘s ratio, and interaction parameters of coefficient of restitution, coefficient of rolling friction, and coefficient of static friction on mass fraction was performed after 156 ASABE sieve-shaking DEM simulation runs, generated using Latin Hypercube Design (LHD) design of experiment (DOE) from 19 DEM material parameters. DEM simulation using Hertz-Mindlin with flexible bond contact laws and DOE optimized material properties successfully reproduced the mass fractions retained in ASABE sieves at 9.8% mean relative error and a coefficient of determination of R2 = 0.87. Here, the DEM methodology developed for mechanical WPC mass fractionation could be deployed to perform virtual design of feedstock handling equipment and performance analysis of mechanical fraction systems.

09 BIOMASS FUELS↗
DOE OSTI2024

Epoxy Coating of Biofiber: An Effective Modifier of Biofiber Physical and Flow Properties for Improved Tensile Behavior of Biofiber-Reinforced Biocomposite

Biocomposites combine renewable, plant-based fibers with degradable polymers and are an attractive option for sustainable, lightweight, and cost-effective materials with a low carbon footprint, especially for large-scale additive manufacturing. One of the major challenges in the widespread adoption of biocomposites is that their mechanical performance is significantly inferior to that of synthetic composites. Surface treatment is a common and effective technique to improve the mechanical properties of the biofibers used in biocomposites. This study aims to investigate the physical and flow properties of surface-treated biofibers, as well as the tensile properties of their PLA-based biocomposite, to gain insights into how surface treatment changes the fiber‘s characteristics and biocomposite‘s mechanical properties. Surface treatment was created using a two-component epoxy system by reacting poly(bisphenol A-co-epichlorohydrin) glycidyl end-capped (PBG) and dicyandiamide (DICY). The treatment was tested on two different biofibers (loblolly pine and corn stover fibers) with three different PBG/DICY molar ratios (0.25, 0.5, and 2). Results showed that surface-treated fibers improved the tensile strength and Young‘s modulus of the biocomposites. Loblolly pine biocomposites from fibers treated with a PBG/DICY ratio of 0.25 exhibited the best tensile properties. The surface treatment resulted in a more loosely dispersed fiber bulk structure, as evidenced by less fiber agglomeration into smaller particle sizes, higher fiber sphericity, and lower loose bulk density. This can enhance stress distribution and the overall mechanical performance of the biocomposites. Additionally, surface-treated fibers exhibited better dynamic flow properties.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Quantifying tissue mechanical properties using photoplethysmography

Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young s Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance.

Akl, Tony↗
DOE OSTI2017

High-Temperature Inorganic Self-Healing Inorganic Cement Composites

The data files below summarize the results from various experiments testing properties of high-temperature self-healing inorganic cement composites. These properties include cement-carbon steel bond strength, Young's modulus recovery, matrix recovery strength, and compressive strength and Yonug's modulus for cement composites modified with Pozzolanic Clay additives.

15 GEOTHERMAL ENERGY↗