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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 OSTI2014

Heat treatment effects on mechanical properties of atmospheric plasma sprayed Fe{sub x}B coatings on Al substrate

In this work, we draw attention to determination of heat-treatment effects on mechanical properties of atmospheric plasma sprayed (APS) Fe{sub x}B coatings on aluminum substrates by micro-indentation technique. With this regard, iron boride powders of Fe-18.8B-0.2C-0.5Si-0.8Al (wt.%) were deposited onto Al substrates by APS in order to improve the mechanical properties of Al surface. As-sprayed coatings are composed of mainly Fe{sub x}B and iron matrix supersaturated with boron owing to the rapid solidification of molten droplets flattened on a substrate. It was observed that APS coatings exhibited characteristic wavy layered structure having porosity, inclusions, and semi-melted particles. The postfurnace treatment of APS coatings was carried out at temperatures ranged from 450 to 550°C in an argon atmosphere. The post-treatment applied for APS deposits led to increase in hardness of 40% without showing cracks. Furthermore, micro-mechanical properties of Fe{sub x}B coatings were examined by Shimadzu Dynamic Ultra-Microhardness Tester for estimating Young’s modulus and hardness due to load—unload sensing analysis by applying different loads such as 160, 320, and 640 mN to determine load and indentation depth dependency of APS Fe{sub x}B on Al substrate for each samples, in details.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Properties of SiC-Si made via binder jet 3D printing of SiC powder, carbon addition, and silicon melt infiltration

In this work, we report the physical and mechanical properties of ceramic composite materials fabricated by binder jet 3D printing (BJ3DP) with silicon carbide (SiC) powders, followed by phenolic resin infiltration and pyrolysis (IP) to generate carbon, and a final reactive silicon melt infiltration step. After two phenolic resin infiltration and pyrolysis cycles; porosity was less than 2%, Young's modulus was close to 300 GPa, and the flexural strength was 517.6 ± 24.8 MPa. However, diminishing returns were obtained after more than two phenolic resin infiltration and pyrolysis cycles as surface pores in carbon were closed upon the formation of SiC, resulting in reaction choking and residual-free carbon and porosity. The instantaneous coefficient of thermal expansion of the composite was found to be independent of the number of phenolic IP cycles and had values of between 4.2 and 5.0 ppm/°C between 300 and 100°C, whereas the thermal conductivity was found to have a weak dependence on the number of phenolic IP cycles. While the manufacturing procedures described here yielded highly dense, gas impermeable, siliconized SiC composites with properties comparable to those of bulk siliconized silicon carbide processed according to conventional techniques, BJ3DP enables the manufacture of objects with complex shape, unlike conventional techniques.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Multipurpose active scanning probe cantilevers for near-field spectroscopy, scanning tunnel imaging, and atomic-resolution lithography

In this work, we report progress on developing a multipurpose scanning probe cantilever applying gallium nitride nanowires as the probe tip. Gallium nitride nanowires possess high potential as probes due to their straight profile, tunable electrical and optical properties, high Young’s Modulus, durability, and high-yield fabrication process. Their wide bandgap enables them to be pumped to emit ultraviolet pulses which can be used for optical imaging and spectroscopy. They can be doped during growth to be electrically conductive, and their sharp tips obtained during epitaxial growth enable confinement of a high electric field at tip–sample interface. Their sharp tips are obtained during fabrication by their epitaxial growth which eliminates the need for postprocess sharpening that is typically required for standard STM tips. We present results of using gallium nitride nanowires for scanning tunnel microscopy applications of atomic-resolution imaging and lithography, and atomic force microscopy applications of imaging and lithography in vacuum and atmospheric environments.

Engineering↗
DOE OSTI2015

SU-E-J-96: Multi-Axis Dose Accumulation of Noninvasive Image-Guided Breast Brachytherapy Through Biomechanical Modeling of Tissue Deformation Using the Finite Element Method

Purpose: Noninvasive image-guided breast brachytherapy delivers conformal HDR Ir-192 brachytherapy treatments with the breast compressed, and treated in the cranial-caudal and medial-lateral directions. This technique subjects breast tissue to extreme deformations not observed for other disease sites. Given that, commercially-available software for deformable image registration cannot accurately co-register image sets obtained in these two states, a finite element analysis based on a biomechanical model was developed to deform dose distributions for each compression circumstance for dose summation. Methods: The model assumed the breast was under planar stress with values of 30 kPa for Young’s modulus and 0.3 for Poisson’s ratio. Dose distributions from round and skin-dose optimized applicators in cranial-caudal and medial-lateral compressions were deformed using 0.1 cm planar resolution. Dose distributions, skin doses, and dose-volume histograms were generated. Results were examined as a function of breast thickness, applicator size, target size, and offset distance from the center. Results: Over the range of examined thicknesses, target size increased several millimeters as compression thickness decreased. This trend increased with increasing offset distances. Applicator size minimally affected target coverage, until applicator size was less than the compressed target size. In all cases, with an applicator larger or equal to the compressed target size, > 90% of the target covered by > 90% of the prescription dose. In all cases, dose coverage became less uniform as offset distance increased and average dose increased. This effect was more pronounced for smaller target-applicator combinations. Conclusions: The model exhibited skin dose trends that matched MC-generated benchmarking results and clinical measurements within 2% over a similar range of breast thicknesses and target sizes. The model provided quantitative insight on dosimetric treatment variables over a range of clinical circumstances. These findings highlight the need for careful target localization and accurate identification of compression thickness and target offset. Prof. Rivard is a shareholder of Advanced Radiation Therapy, LLC, the manufacturer of the AccuBoost noninvasive image-guided breast brachytherapy system examined herein. None of the other authors have any conflicts-of-interest for this work.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

WE-AB-202-05: Validation of Lung Stress Maps for CT-Ventilation Imaging

Purpose: To date, lung CT-ventilation imaging has been based on quantification of local breathing-induced changes in Hounsfield Units (HU) or volume. This work investigates the use of a stress map resulting from a biomechanical deformable image registration (DIR) algorithm as a metric of the ventilation function. Method: Eight lung cancer patients presenting different kinds of ventilation defects were retrospectively analyzed. Additionally, to the 4DCT acquired for radiotherapy planning, five of them had PET and three had SPECT imaging following inhalation of Ga-68 and Tc-99m, respectively. For each patient, the inhale phase of the 4DCT was registered to the exhale phase using Morfeus, a biomechanical DIR algorithm based on the determination of boundary conditions on the lung surfaces and vessel tree. To take into account the heterogeneity of the tissue stiffness in the stress map estimation, each tetrahedral element of the finite-element model was assigned a Young’s modulus ranging from 60kPa to 12MPa, as a function of the HU in the inhale CT. The node displacements and element stresses resulting from the numerical simulation were used to generate three CT-ventilation maps based on: (i) volume changes (Jacobian determinant), (ii) changes in HU, (iii) the maximum principal stress. The voxel-wise correlation between each CT-ventilation map and the PET or SPECT V image was computed in a lung mask. Results: For patients with PET, the mean (min-max) Spearman correlation coefficients r were: 0.33 (0.19–0.45), 0.36 (0.16–0.51) and 0.42 (0.21–0.59) considering the Jacobian, changes in HU and maximum principal stress, respectively. For patients with SPECT V, the mean r were: 0.12 (−0.12–0.43), 0.29 (0.22–0.45) and 0.33 (0.25–0.39). Conclusion: The maximum principal stress maps showed a stronger correlation with the ventilation images than the previously proposed Jacobian or change in HU maps. This metric thus appears promising for CT-ventilation imaging. This work was funded in part by NIH P01CA059827.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Peculiarities of the Structure, Moduli of Elasticity, and Knoop Indentation Patterns of Deformation and Fracture of Single Crystals of Potassium, Rubidium, Cesium, and Ammonium Hydrophthalates

The crystal structure of potassium, rubidium, cesium, and ammonium hydrophthalates is analyzed based on the data in the literature. A relationship between their structure and elastic and mechanical properties has been established for the first time. Young’s moduli, shear moduli, and Poisson’s ratios in the (100), (010), and (001) planes of these crystals are calculated, and Knoop indentation of these planes is performed. Anisotropy of the elastic and mechanical properties of the crystals is revealed. Rubidium, cesium, and ammonium hydrophthalates are found to be partial auxetics. Ammonium hydrophthalate, whose structure contains additional (as compared with other hydrophthalates) hydrogen bonds, exhibits the highest anisotropy of properties.

36 MATERIALS SCIENCE↗
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↗