Bulk Modulus Relaxation in Partially Molten Dunite?
Jackson, I.; Cline, C. J., II
2016-12-01
Synthetic solgel-derived Fo90 olivine was mixed with 3.5 wt % basaltic glass and hot-pressed within Ni/Fe foil to produce a dense aggregate expected to contain a small melt fraction at temperatures ≥ 1100°C. This specimen was precision ground and tested in both torsional and flexural forced oscillation to determine the relaxation behavior of both shear (G) and bulk (K) moduli at seismic frequencies. A recent upgrade of our experimental facility allows such measurements to be made without alteration of the driver/detector geometry, and uses an oscillating bending force rather than a bending moment, as previously described. The torsional and flexural tests were conducted in a gas apparatus at 200 MPa confining pressure, with oscillation periods ranging between 1 and 1000 s, during slow staged-cooling from 1300 to 25°C. Shear modulus and associated dissipation data are consistent with those for melt-bearing olivine specimens previously tested in torsion, with a pronounced dissipation peak superimposed on high-temperature background within the 1-1000 s observational window at temperatures of 1100-1200°C. A filament elongation model relates the observed flexural measurements to the variations along the experimental assembly of the complex Young's modulus (E*), bending moment and diametral moment of inertia. With E* given by 1/E*=1/(3G*) + 1/(9K*), and the complex shear modulus (G*) derived from torsional oscillation, any relaxation of K can be identified. Preliminary modeling shows that the viscoelastic properties in flexure are broadly consistent with those expected from the shear-mode viscoelasticity with anharmonic (real) values of K. However, some discrepancies between modeled results and flexure data at super-solidus temperatures require further investigation of possible differences in shear modulus relaxation between the torsional and flexural modes, and of potential relaxation of the bulk modulus through stress-induced changes in melt redistribution and
Bulk modulus of metals according to structureless pseudopotential ...
African Journals Online (AJOL)
structureless pseudopotential model was fully developed. The developed method was used to calculate the bulk modulus and kinetic energy contribution to the bulk modulus of 46 elemental metals. The results obtained were compared with experimental values and their variation with electron density parameter was studied ...
Multiphase composites with extremal bulk modulus
DEFF Research Database (Denmark)
Gibiansky, L. V.; Sigmund, Ole
2000-01-01
This paper is devoted to the analytical and numerical study of isotropic elastic composites made of three or more isotropic phases. The ranges of their effective bulk and shear moduli are restricted by the Hashin-Shtrikman-Walpole (HSW) bounds. For two-phase composites, these bounds are attainabl...... isotropic three-dimensional three-phase composites with cylindrical inclusions of arbitrary cross-sections (plane strain problem) or transversely isotropic thin plates (plane stress or bending of plates problems). (C) 2000 Elsevier Science Ltd. All rights reserved....
Unveiling descriptors for predicting the bulk modulus of amorphous carbon
Takahashi, Keisuke; Tanaka, Yuzuru
2017-02-01
Descriptors for the bulk modulus of amorphous carbon are investigated through the implementation of data mining where data sets are prepared using first-principles calculations. Data mining reveals that the number of bonds in each C atom and the density of amorphous carbon are found to be descriptors representing the bulk modulus. Support vector regression (SVR) within machine learning is implemented and descriptors are trained where trained SVR is able to predict the bulk modulus of amorphous carbon. An inverse problem, starting from the bulk modulus towards structural information of amorphous carbon, is performed and structural information of amorphous carbon is successfully predicted from the desired bulk modulus. Thus, treating several physics factors in multidimensional space allows for the prediction of physical phenomena. In addition, the reported approach proposes that "big data" can be generated from a small data set using machine learning if descriptors are well defined. This would greatly change how amorphous carbon would be treated and help accelerate further development of amorphous carbon materials.
The dynamic bulk modulus of three glass-forming liquids
DEFF Research Database (Denmark)
Niss, Kristine; Christensen, Tage Emil; Dyre, J. C.
2014-01-01
We present dynamic adiabatic bulk modulus data for three organic glass-forming liquids: two van der Waal's liquids, trimethyl-pentaphenyl-trisiloxane (DC705) and dibuthyl phtalate (DBP), and one hydrogen-bonded liquid, 1,2-propanediol (PD). All three liquids are found to obey time-temperature sup......We present dynamic adiabatic bulk modulus data for three organic glass-forming liquids: two van der Waal's liquids, trimethyl-pentaphenyl-trisiloxane (DC705) and dibuthyl phtalate (DBP), and one hydrogen-bonded liquid, 1,2-propanediol (PD). All three liquids are found to obey time...
Effect of bulk modulus on performance of a hydrostatic transmission ...
Indian Academy of Sciences (India)
) and fuzzy controllers on the angular velocity of a hydrostatic transmission system by means of Matlab-Simulink. A very novel aspect is that it includes the analysis of the effect of bulk modulus on system control. Simulation results demonstrates ...
Isentropic Bulk Modulus: Development of a Federal Test Method
2016-01-01
bulk modulus space from synthetic iso -paraffinic fuels to petroleum-based diesel fuels. The test fuels are identified in Table 1. A testing order and...13000 100 14000 100 15000 100 UNCLASSIFIED UNCLASSIFIED 7 3.3 ROUND ROBIN PROCEDURE The following notes were provided to the participating...2 Table A-1. Sample 6065 at 35 °C Density psi 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 Avg g/cm3
A simple model for calculating the bulk modulus of the mixed ionic ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 77; Issue 4. A simple model for calculating the bulk modulus of the mixed ionic ... in terms of the bulk modulus of the end members alone. The calculated values are comparable to those deduced from the three-body potential model (TDPM) by applying Vegard's law.
CSIR Research Space (South Africa)
Anochie-Boateng, Joseph
2011-07-01
Full Text Available correlation models for the soil sample tested. These models can be used for evaluating the impact of moisture on bulk modulus of fine-grained soils with similar characteristics for their sustainable use in foundation applications under off-road construction...
Total energy, equation of state and bulk modulus of AlP, AlAs and ...
Indian Academy of Sciences (India)
% to 11.85% which shows that contribution from higher order terms are important for zinc-blende-type crystals. The calculated numerical results of the total energy, energy band gap at Jones-zone face and bulk modulus of these compounds are.
Enhanced bulk modulus and reduced transition pressure in gamma-Fe2O3 nanocrystals
DEFF Research Database (Denmark)
Jiang, Jianzhong; Olsen, J. Staun; Gerward, Leif
1998-01-01
Synchrotron radiation X-ray diffraction studies of gamma-Fe2O3 have been performed with emphasis on the pressure-induced phase transformation gamma(maghemite) - alpha(hematite) and the equation of state of the nanophase material. For gamma-Fe2O3 the bulk modulus has been found to increase from 203...
Mechanical properties of Fe rich Fe–Si alloys: ab initio local bulk-modulus viewpoint
Bhattacharya, Somesh Kr; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori; Saengdeejing, Arkapol; Chen, Ying; Mohri, Tetsuo
2017-11-01
Fe-rich Fe–Si alloys show peculiar bulk-modulus changes depending on the Si concentration in the range of 0–15 at.%Si. In order to clarify the origin of this phenomenon, we have performed density-functional theory calculations of supercells of Fe–Si alloy models with various Si concentrations. We have applied our recent techniques of ab initio local energy and local stress, by which we can obtain a local bulk modulus of each atom or atomic group as a local constituent of the cell-averaged bulk modulus. A2-phase alloy models are constructed by introducing Si substitution into bcc Fe as uniformly as possible so as to prevent mutual neighboring, while higher Si concentrations over 6.25 at.%Si lead to contacts between SiFe8 cubic clusters via sharing corner Fe atoms. For 12.5 at.%Si, in addition to an A2 model, we deal with partial D03 models containing local D03-like layers consisting of edge-shared SiFe8 cubic clusters. For the cell-averaged bulk modulus, we have successfully reproduced the Si-concentration dependence as a monotonic decrease until 11.11 at.%Si and a recovery at 12.5 at.%Si. The analysis of local bulk moduli of SiFe8 cubic clusters and Fe regions is effective to understand the variations of the cell-averaged bulk modulus. The local bulk moduli of Fe regions become lower for increasing Si concentration, due to the suppression of bulk-like d–d bonding states in narrow Fe regions. For higher Si concentrations till 11.11 at.%Si, corner-shared contacts or 1D chains of SiFe8 clusters lead to remarkable reduction of local bulk moduli of the clusters. At 12 at.%Si, on the other hand, two- or three-dimensional arrangements of corner- or edge-shared SiFe8 cubic clusters show greatly enhanced local bulk moduli, due to quite different bonding nature with much stronger p-d hybridization. The relation among the local bulk moduli, local electronic and magnetic structures, and local configurations such as connectivity of SiFe8 clusters and Fe-region sizes has
Effect of bulk modulus on deformation of the brain under rotational accelerations
Ganpule, S.; Daphalapurkar, N. P.; Cetingul, M. P.; Ramesh, K. T.
2017-12-01
Traumatic brain injury such as that developed as a consequence of blast is a complex injury with a broad range of symptoms and disabilities. Computational models of brain biomechanics hold promise for illuminating the mechanics of traumatic brain injury and for developing preventive devices. However, reliable material parameters are needed for models to be predictive. Unfortunately, the properties of human brain tissue are difficult to measure, and the bulk modulus of brain tissue in particular is not well characterized. Thus, a wide range of bulk modulus values are used in computational models of brain biomechanics, spanning up to three orders of magnitude in the differences between values. However, the sensitivity of these variations on computational predictions is not known. In this work, we study the sensitivity of a 3D computational human head model to various bulk modulus values. A subject-specific human head model was constructed from T1-weighted MRI images at 2-mm3 voxel resolution. Diffusion tensor imaging provided data on spatial distribution and orientation of axonal fiber bundles for modeling white matter anisotropy. Non-injurious, full-field brain deformations in a human volunteer were used to assess the simulated predictions. The comparison suggests that a bulk modulus value on the order of GPa gives the best agreement with experimentally measured in vivo deformations in the human brain. Further, simulations of injurious loading suggest that bulk modulus values on the order of GPa provide the closest match with the clinical findings in terms of predicated injured regions and extent of injury.
DEFF Research Database (Denmark)
Hafis, S. M.; Christiansen, P.; Martins, P. A. F.
2016-01-01
facilitates the lubricant entrainment, pressurization and possible escape by micro-plasto-hydrodynamic lubrication. In order to model these mechanisms an important lubricant propertyd esignated as the bulk modulus is needed for characterizing the compressibility of the lubricant. The present paper describes...... a simple, practical test to determine the bulk modulus. Combination of the experimental upsetting of an axisymmetric metal workpiece containing a truncated conical surface pocket with an inverse finite element analysis of the test allows determining the lubricant bulk modulus. The finite element analysis...
Wu, H. I.; Spence, R. D.; Sharpe, P. J.; Goeschl, J. D.
1985-01-01
The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.
Raman Spectra and Bulk Modulus of Nanodiamond in a Size Interval of 2-5 nm
Popov, Mikhail; Churkin, Valentin; Kirichenko, Alexey; Denisov, Viktor; Ovsyannikov, Danila; Kulnitskiy, Boris; Perezhogin, Igor; Aksenenkov, Viktor; Blank, Vladimir
2017-10-01
Nanodiamond in a 2-5-nm size interval (which is typical for an appearance of quantum confinement effect) show Raman spectra composed of 3 bands at 1325, 1600, and 1500 cm-1 (at the 458-nm laser excitation) which shifts to 1630 cm-1 at the 257-nm laser excitation. Contrary to sp2-bonded carbon, relative intensities of the bands do not depend on the 458- and 257-nm excitation wavelengths, and a halfwidth and the intensity of the 1600 cm-1 band does not change visibly under pressure at least up to 50 GPa. Bulk modulus of the 2-5-nm nanodiamond determined from the high-pressure study is around 560 GPa. Studied 2-5-nm nanodiamond was purified from contamination layers and dispersed in Si or NaCl.
Yoneda, Akira; Fukui, Hiroshi; Gomi, Hitoshi; Kamada, Seiji; Xie, Longjian; Hirao, Naohisa; Uchiyama, Hiroshi; Tsutsui, Satoshi; Baron, Alfred Q. R.
2017-09-01
We measured the elasticity of single crystal gold (Au) and its lattice parameters under high pressure using inelastic X-ray scattering (IXS). The elastic moduli were obtained at five pressure points between 0 and 20 GPa. The pressure variation of the bulk modulus displays anomalous behavior, being nearly constant up to ˜5 GPa, and then steeply increasing at higher pressure. A similar anomaly is observed in first-principles calculations. An absolute pressure scale was derived by direct numerical integration of the bulk modulus over volume change. This yields a scale that gives slightly lower pressure values than those of previous work, about 5-10% lower at ˜20 GPa.
Tapia, A; Villanueva, C; Peón-Escalante, R; Quintal, R; Medina, J; Peñuñuri, F; Avilés, F
2015-06-01
Dedicated bond force constant and bulk modulus of C n fullerenes (n = 20, 28, 36, 50, 60) are computed using density functional theory (DFT). DFT predicts bond force constants of 611, 648, 675, 686, and 691 N/m, for C20, C28, C36, C50, and C60, respectively, indicating that the bond force constant increases for larger fullerenes. The bulk modulus predicted by DFT increases with decreased fullerene diameter, from 0.874 TPa for C60 to 1.830 TPa for C20. The bond force constants predicted by DFT are then used as an input for finite element analysis (FEA) of the fullerenes, considered as spatial frames in structural models where the bond stiffness is represented by the DFT-computed bond force constant. In agreement with DFT, FEA predicts that smaller fullerenes are stiffer, and underestimates the bulk modulus with respect to DFT. The difference between the FEA and DFT predictions of the bulk modulus decreases as the size of the fullerene increases, from 20.9% difference for C20 to only 4% difference for C60. Thus, it is concluded that knowing the appropriate bond force constant, FEA can be used as a plausible approximation to model the elastic behavior of small fullerenes.
High Bulk Modulus of Ionic Liquid and Effects on Performance of Hydraulic System
Directory of Open Access Journals (Sweden)
Milan Kambic
2014-01-01
Full Text Available Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication, and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus, compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systems’ dynamic responses.
Bhakta, Tuhin; Avseth, Per; Landrø, Martin
2016-12-01
Fluid substitution plays a vital role in time-lapse seismic modeling and interpretation. It is, therefore, very important to quantify as exactly as possible the changes in fluid bulk modulus due to changes in reservoir parameters. In this paper, we analyze the sensitivities in effective fluid bulk modulus due to changes in reservoir parameters like saturation, pore-pressure and temperature. The sensitivities are analyzed for two extreme bounds, i.e. the Voigt average and the Reuss average, for various fluid combinations (i.e. oil-water, gas-water and gas-oil). We quantify that the effects of pore-pressure and saturation changes are highest in the case of gas-water combination, while the effect of temperature is highest for oil-gas combination. Our results show that sensitivities vary with the bounds, even for same amount of changes in any reservoir parameter. In 4D rock physics studies, we often neglect the effects of pore-pressure or temperature changes assuming that those effects are negligible compare to the effect due to saturation change. Our analysis shows that pore-pressure and temperature changes can be vital and sometimes higher than the effect of saturation change. We investigate these effects on saturated rock bulk modulus. We first compute frame bulk modulus using the Modified Hashin Shtrikman (MHS) model for carbonate rocks and then perform fluid substitution using the Gassmann equation. We consider upper bound of the MHS as elastic behavior for stiffer rocks and lower bound of the MHS as elastic behavior for softer rocks. We then investigate four various combinations: stiff rock with upper bound (the Voigt bound) as effective fluid modulus, stiff rock with lower bound (Reuss bound) as effective fluid modulus, soft rock with upper bound as effective fluid modulus and soft rock with lower bound as effective fluid modulus. Our results show that the effect of any reservoir parameter change is highest for soft rock and lower bound combination and lowest
High-pressure Synthesis and Bulk Modulus of Non-centrosymmetric Superconductor Mo3Al2C
Sekine, C.; Sai, U.; Hayashi, J.; Kawamura, Y.; Bauer, E.
2017-10-01
Mo3Al2C is a superconductor without inversion symmetry (the transition temperature T C ∼ 9K). We have succeeded in preparing high-quality samples of Mo3Al2C using the high-pressure synthesis technique. The samples were characterized by powder x-ray diffraction (XRD) analysis. Furthermore, powder XRD patterns for the samples with synchrotron radiation have been studied under high pressures up to around 10 GPa and the volume versus pressure curve for the compound has been investigated. A bulk modulus was estimated to be 221 GPa.
Oh, Jae Eun
2012-02-01
Using a diamond anvil cell, 14 Å tobermorite, a structural analogue of calcium silicate hydrates (C-S-H), was examined by high-pressure synchrotron X-ray diffraction up to 4.8 GPa under hydrostatic conditions. The bulk modulus of 14 Å tobermorite was calculated, K o = 47 GPa. Comparison of the current results with previous high pressure studies on C-S-H(I) indicates that: (1) the compression behavior of the lattice parameters a and b of 14 Å tobermorite and C-S-H(I) are very similar, implying that both materials may have very similar Ca-O layers, and also implying that an introduction of structural defects into the Ca-O layers may not substantially change in-plane incompressibility of the ab plane of 14 Å tobermorite; and (2) the bulk modulus values of 14 Å tobermorite and C-S-H(I) are dominated by the incompressibility of the lattice parameter c, which is directly related to the interlayer spacing composed of dreierketten silicate chains, interlayer Ca, and water molecules. © 2011 Elsevier Ltd. All rights reserved.
Allen, Philip B.
2015-08-01
The quasiharmonic (QH) approximation uses harmonic vibrational frequencies ωQ ,H(V ) computed at volumes V near V0 where the Born-Oppenheimer (BO) energy Eel(V ) is minimum. When this is used in the harmonic free energy, QH approximation gives a good zeroth order theory of thermal expansion and first-order theory of bulk modulus, where nth-order means smaller than the leading term by ɛn, where ɛ =ℏ ωvib/Eel or kBT /Eel , and Eel is an electronic energy scale, typically 2 to 10 eV. Experiment often shows evidence for next-order corrections. When such corrections are needed, anharmonic interactions must be included. The most accessible measure of anharmonicity is the quasiparticle (QP) energy ωQ(V ,T ) seen experimentally by vibrational spectroscopy. However, this cannot just be inserted into the harmonic free energy FH. In this paper, a free energy is found that corrects the double-counting of anharmonic interactions that is made when F is approximated by FH( ωQ(V ,T ) ) . The term "QP thermodynamics" is used for this way of treating anharmonicity. It enables (n +1 ) -order corrections if QH theory is accurate to order n . This procedure is used to give corrections to the specific heat and volume thermal expansion. The QH formulas for isothermal (BT) and adiabatic (BS) bulk moduli are clarified, and the route to higher-order corrections is indicated.
Hargis, Craig W.
2013-12-12
The predominant phase of calcium sulfoaluminate cement, Ca 4(Al6O12)SO4, was investigated using high-pressure synchrotron X-ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al 6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O 12)SO4. The compressibility of Ca4(Al 6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O 12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H 2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other cement clinker phases such as tricalcium aluminate and less compressible than hydrated cement phases such as ettringite and hemicarboaluminate. © 2013 The American Ceramic Society.
Oh, Jae Eun
2011-11-01
Crystalline zeolitic materials, such as hydroxycancrinite, hydroxysodalite, herschelite and nepheline, are often synthesized from geopolymerization using fly-ash and solutions of NaOH at high temperatures. Comprised mainly of 6-membered aluminosilicate rings that act as basic building units, their crystal structures may provide insight into the reaction products formed in NaOH-activated fly ash-based geopolymers. Recent research indicates that the hydroxycancrinite and hydroxysodalite may play an important role as possible analogues of zeolitic precursor in geopolymers. Herein is reported a high pressure synchrotron study of the behavior of hydroxycancrinite exposed to pressures up to 6.1 GPa in order to obtain its bulk modulus. A refined equation of state for hydroxycancrinite yielded a bulk modulus of Ko = 46 ± 5 GPa (assuming Ko′ = 4.0) for a broad range of applied pressure. When low pressure values are excluded from the fit and only the range of 2.5 and 6.1 GPa is considered, the bulk modulus of hydroxycancrinite was found to be Ko = 46.9 ± 0.9 GPa (Ko′ = 4.0 ± 0.4, calculated). Comparison with the literature shows that all zeolitic materials possessing single 6-membered rings (i.e., hydroxycancrinite, sodalite and nepheline) have similar bulk moduli. © 2011 Elsevier Ltd. All rights reserved.
Schlosser, Herbert; Ferrante, John
1989-01-01
The previous work of Schlosser and Ferrante (1988) on universality in solids is extended to the study of liquid metals. As in the case of solids, to a good approximation, in the absence of phase transitions, plots of the logarithm of the reduced-pressure function H, of the reduced-isothermal-bulk-modulus function b, and of the reduced-sound-velocity function v are all linear in 1-X. Finally, it is demonstrated that ln(Cp/C/v) is also linear in 1-X, where X = (V/V/0/)exp 1/3), and V(0) is the volume at zero pressure.
Ridgway, Cathy; Bawuah, Prince; Markl, Daniel; Zeitler, J Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik; Gane, Patrick
2017-06-30
The physical properties and mechanical integrity of pharmaceutical tablets are of major importance when loading with active pharmaceutical ingredient(s) (API) in order to ensure ease of processing, control of dosage and stability during transportation and handling prior to patient consumption. The interaction between API and excipient, acting as functional extender and binder, however, is little understood in this context. The API indomethacin is combined in this study with microcrystalline cellulose (MCC) at increasing loading levels. Tablets from the defined API/MCC ratios are made under conditions of controlled porosity and tablet thickness, resulting from different compression conditions, and thus compaction levels. Mercury intrusion porosimetry is used to establish the accessible pore volume, pore size distribution and, adopting the observed region of elastic intrusion-extrusion at high pressure, an elastic bulk modulus of the skeletal material is recorded. Porosity values are compared to previously published values derived from terahertz (THz) refractive index data obtained from exactly the same tablet sample sets. It is shown that the elastic bulk modulus is dependent on API wt% loading under constant tablet preparation conditions delivering equal dimensions and porosity. The findings are considered of novel value in respect to establishing consistency of tablet production and optimisation of physical properties. Copyright © 2017 Elsevier B.V. All rights reserved.
Oh, Jae Eun
2011-01-01
Synthetic basic sodalite, Na8[AlSiO4] 6(OH)2•2H2O, cubic, P43n, (also known as hydroxysodalite hydrate) was prepared by the alkaline activation of amorphous aluminosilicate glass, obtained from the phase separation of Class F fly ash. The sample was subjected to a process similar to geopolymerization, using high concentrations of a NaOH solution at 90 °C for 24 hours. Basic sodalite was chosen as a representative analogue of the zeolite precursor existing in Na-based Class F fly ash geopolymers. To determine its bulk modulus, high-pressure synchrotron X-ray powder diffraction was applied using a diamond anvil cell (DAC) up to a pressure of 4.5 GPa. A curve-fit with a truncated third-order Birch-Murnaghan equation of state with a fixed K\\'o = 4 to pressure-normalized volume data yielded the isothermal bulk modulus, K o = 43 ± 4 GPa, indicating that basic sodalite is more compressible than sodalite, possibly due to a difference in interactions between the framework host and the guest molecules. © 2010 Elsevier Ltd.
Srivastava, Archana; Thakur, Rasna; Gaur, N. K.
2014-04-01
Specific heat (Cp) thermal expansion (α) and Bulk modulus (BT) of lightly doped Rare Earth manganites (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B3+ = Fe3+,Cr3+,Ga3+,Al3+,Ru4+); (0.3specific heat (Cp)lat of (La0.3Pr0.7)0.65Ca0.35Mn0.97Fe0.03O3 as a function of temperature (10K≤T≤ 200K) is found to be in agreement with the published data. The trend of variation of Debye temperature with B-site cationic radius is predicted probably for the first time for the B-site doped rare earth manganites.
Modulus-Pressure Equation for Confined Fluids
Gor, Gennady Y; Shen, Vincent K; Bernstein, Noam
2016-01-01
Ultrasonic experiments allow one to measure the elastic modulus of bulk solid or fluid samples. Recently such experiments have been carried out on fluid-saturated nanoporous glass to probe the modulus of a confined fluid. In our previous work [J. Chem. Phys., (2015) 143, 194506], using Monte Carlo simulations we showed that the elastic modulus $K$ of a fluid confined in a mesopore is a function of the pore size. Here we focus on modulus-pressure dependence $K(P)$, which is linear for bulk materials, a relation known as the Tait-Murnaghan equation. Using transition-matrix Monte Carlo simulations we calculated the elastic modulus of bulk argon as a function of pressure and argon confined in silica mesopores as a function of Laplace pressure. Our calculations show that while the elastic modulus is strongly affected by confinement and temperature, the slope of the modulus versus pressure is not. Moreover, the calculated slope is in a good agreement with the reference data for bulk argon and experimental data for ...
Directory of Open Access Journals (Sweden)
Xi Liu
2016-12-01
Full Text Available The compressibility of the spinel solid solutions, (Mg1−xMnxCr2O4 with x = 0.00 (0, 0.20 (0, 0.44 (2, 0.61 (2, 0.77 (2 and 1.00 (0, has been investigated by using a diamond-anvil cell coupled with synchrotron X-ray radiation up to ∼10 GPa (ambient T. The second-order Birch–Murnaghan equation of state was used to fit the PV data, yielding the following values for the isothermal bulk moduli (KT, 198.2 (36, 187.8 (87, 176.1 (32, 168.7 (52, 192.9 (61 and 199.2 (61 GPa, for the spinel solid solutions with x = 0.00 (0, 0.20 (0, 0.44 (2, 0.61 (2, 0.77 (2 and 1.00 (0, respectively (KT′ fixed as 4. The KT value of the MgCr2O4 spinel is in good agreement with existing experimental determinations and theoretical calculations. The correlation between the KT and x is not monotonic, with the KT values similar at both ends of the binary MgCr2O4MnCr2O4, but decreasing towards the middle. This non-monotonic correlation can be described by two equations, KT = −49.2 (11x + 198.0 (4 (x ≤ ∼0.6 and KT = 92 (41x + 115 (30 (x ≥ ∼0.6, and can be explained by the evolution of the average bond lengths of the tetrahedra and octahedra of the spinel solid solutions. Additionally, the relationship between the thermal expansion coefficient and composition is correspondingly reinterpreted, the continuous deformation of the oxygen array is demonstrated, and the evolution of the component polyhedra is discussed for this series of spinel solid solutions. Our results suggest that the correlation between the KT and composition of a solid solution series may be complicated, and great care should be paid while estimating the KT of some intermediate compositions from the KT of the end-members.
Effect of bulk modulus on performance of a hydrostatic transmission ...
Indian Academy of Sciences (India)
logic is most likely the result of present popular consumer products employing fuzzy logic. The advantages of this method are its applicability to nonlinear systems, simplicity, good performance and robust character. These days, this method is being applied to engineer- ing control systems such as robot control, flight control, ...
Application of the tight-binding method to the elastic modulus of C60 and carbon nanotube
Energy Technology Data Exchange (ETDEWEB)
Cai, J.; Bie, R.F.; Tan, X.M.; Lu, C
2004-02-15
The bulk modulus of C60, Young's modulus of carbon nanotube, and the corresponding bond length are calculated by the tight binding method (M.J. Mehl and D.A. Papaconstantopoulos, Phys. Rev. B 54 (1996) 4519). The calculated bond lengths of C60 and the nanotube are in good agreement with experiments or first principle calculations. The calculated Young's modulus of the nanotube is found to be equal to 0.95 TPa, the bulk modulus of C60 is 0.86 TPa. These results also fall within the range of experimental data. In addition, the bulk modulus formula of C60 and Young's modulus of nanotubes are discussed further.
Standard test method for Young's modulus, tangent modulus, and chord modulus
American Society for Testing and Materials. Philadelphia
2004-01-01
1.1 This test method covers the determination of Young's modulus, tangent modulus, and chord modulus of structural materials. This test method is limited to materials in which and to temperatures and stresses at which creep is negligible compared to the strain produced immediately upon loading and to elastic behavior. 1.2 Because of experimental problems associated with the establishment of the origin of the stress-strain curve described in 8.1, the determination of the initial tangent modulus (that is, the slope of the stress-strain curve at the origin) and the secant modulus are outside the scope of this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory require...
Modulus optimum for digital controllers
Directory of Open Access Journals (Sweden)
Víteèek Antonín
2003-12-01
Full Text Available The paper extends the popular modulus optimum with the original approach for the conventional digital controllers. The use of the D-transform allows obtaining the uniform computing formulas for the values of the digital and analog controller tuning parameters. The use is shown on an example.
Ultrasonic metamaterials with negative modulus.
Fang, Nicholas; Xi, Dongjuan; Xu, Jianyi; Ambati, Muralidhar; Srituravanich, Werayut; Sun, Cheng; Zhang, Xiang
2006-06-01
The emergence of artificially designed subwavelength electromagnetic materials, denoted metamaterials, has significantly broadened the range of material responses found in nature. However, the acoustic analogue to electromagnetic metamaterials has, so far, not been investigated. We report a new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance. These materials have an effective dynamic modulus with negative values near the resonance frequency. As a result, these ultrasonic metamaterials can convey acoustic waves with a group velocity antiparallel to phase velocity, as observed experimentally. On the basis of homogenized-media theory, we calculated the dispersion and transmission, which agrees well with experiments near 30 kHz. As the negative dynamic modulus leads to a richness of surface states with very large wavevectors, this new class of acoustic metamaterials may offer interesting applications, such as acoustic negative refraction and superlensing below the diffraction limit.
Elastic modulus of hard tissues.
Bar-On, Benny; Wagner, H Daniel
2012-02-23
This work aims at evaluating the elastic modulus of hard biological tissues by considering their staggered platelet micro-structure. An analytical expression for the effective modulus along the stagger direction is formulated using three non-dimensional structural variables. Structures with a single staggered hierarchy (e.g. collagen fibril) are first studied and predictions are compared with the experimental results and finite element simulations from the literature. A more complicated configuration, such as an array of fibrils, is analyzed next. Finally, a mechanical model is proposed for tooth dentin, in which variations in the multi-scale structural hierarchy are shown to significantly affect the macroscopic mechanical properties. Copyright © 2011 Elsevier Ltd. All rights reserved.
Modulus stabilization in a non-flat warped braneworld scenario
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Indrani [S.N. Bose National Centre for Basic Sciences, Department of Astrophysics and Cosmology, Kolkata (India); SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-05-15
The stability of the modular field in a warped brane world scenario has been a subject of interest for a long time. Goldberger and Wise (GW) proposed a mechanism to achieve this by invoking a massive scalar field in the bulk space-time neglecting the back-reaction. In this work, we examine the possibility of stabilizing the modulus without bringing about any external scalar field. We show that instead of flat 3-branes as considered in Randall-Sundrum (RS) warped braneworld model, if one considers a more generalized version of warped geometry with de Sitter 3-brane, then the brane vacuum energy automatically leads to a modulus potential with a metastable minimum. Our result further reveals that in this scenario the gauge hierarchy problem can also be resolved for an appropriate choice of the brane's cosmological constant. (orig.)
High elastic modulus polymer electrolytes
Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
2013-10-22
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.
Li, Ming; Zhao, Aiwu; Jiang, Rui; Wang, Dapeng; Li, Da; Guo, Hongyan; Tao, Wenyu; Gan, Zibao; Zhang, Maofeng
2011-02-01
We studied the influence of the elastic modulus on the gecko-inspired dry adhesion by regulating the elastic modulus of bulk polyurethane combined with changing the size of microarrays. Segmented polyurethane (PU) was utilized to fabricate micro arrays by the porous polydimethyl siloxane (PDMS) membrane molding method. The properties of the micro arrays, such as the elastic modulus and adhesion, were investigated by Triboindenter. The study demonstrates that bulk surfaces show the highest elastic modulus, with similar values at around 175 MPa and decreasing the arrays radius causes a significant decrease in E, down to 0.62 MPa. The corresponding adhesion experiments show that decrease of the elastic modulus can enhance the adhesion which is consistent with the recent theoretical models.
Ancestrally high elastic modulus of gecko setal beta-keratin.
Peattie, Anne M; Majidi, Carmel; Corder, Andrew; Full, Robert J
2007-12-22
Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1MPa. Geckos possess subdigital adhesives composed mostly of beta-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of beta-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of beta-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa +/- 0.15s.e.; n=24 setae) and Ptyodactylus hasselquistii (1.4 GPa +/- 0.15s.e.; n=24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.
Young's modulus of multi-layer microcantilevers
Deng, Zhikang; Deng, Jinglan; He, Liang; Zhuo, Rongshu; Zhu, Ruiqi; Shi, Yang; Liu, Hui; Yang, Wei; Yuan, Hui; Chen, Yiming; Huang, Yue; Zheng, Yi
2017-12-01
A theoretical model for calculating the Young's modulus of multi-layer microcantilevers with a coating is proposed, and validated by a three-dimensional (3D) finite element (FE) model using ANSYS parametric design language (APDL) and atomic force microscopy (AFM) characterization. Compared with typical theoretical models (Rayleigh-Ritz model, Euler-Bernoulli (E-B) beam model and spring mass model), the proposed theoretical model can obtain Young's modulus of multi-layer microcantilevers more precisely. Also, the influences of coating's geometric dimensions on Young's modulus and resonant frequency of microcantilevers are discussed. The thickness of coating has a great influence on Young's modulus and resonant frequency of multi-layer microcantilevers, and the coating should be considered to calculate Young's modulus more precisely, especially when fairly thicker coating is employed.
Energy Technology Data Exchange (ETDEWEB)
Omar, Yamila M.; Al Ghaferi, Amal, E-mail: aalghaferi@masdar.ac.ae, E-mail: mchiesa@masdar.ac.ae; Chiesa, Matteo, E-mail: aalghaferi@masdar.ac.ae, E-mail: mchiesa@masdar.ac.ae [Laboratory for Energy and Nanosciences, Institute Center for Energy (iEnergy), Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates)
2015-07-20
Extensive work has been done in order to determine the bulk elastic modulus of isotropic samples from force curves acquired with atomic force microscopy. However, new challenges are encountered given the development of new materials constructed of one-dimensional anisotropic building blocks, such as carbon nanostructured paper. In the present work, we establish a reliable framework to correlate the elastic modulus values obtained by amplitude modulation atomic force microscope force curves, a nanoscopic technique, with that determined by traditional macroscopic tensile testing. In order to do so, several techniques involving image processing, statistical analysis, and simulations are used to find the appropriate path to understand how macroscopic properties arise from anisotropic nanoscale components, and ultimately, being able to calculate the value of bulk elastic modulus.
Energy Technology Data Exchange (ETDEWEB)
Singh, J.P.; Sutaria, M. [Argonne National Lab., IL (United States). Energy Technology Div.; Ferber, M. [Oak Ridge National Lab., TN (United States)
1997-01-01
Elastic modulus of an yttria partially stabilized zirconia (YSZ) thermal barrier coating (TBC) was evaluated with a Knoop indentation technique. The measured elastic modulus values for the coating ranged from 68.4 {+-} 22.6 GPa at an indentation load of 50 g to 35.7 {+-} 9.8 at an indentation load of 300 g. At higher loads, the elastic modulus values did not change significantly. This steady-state value of 35.7 GPa for ZrO{sub 2} TBC agreed well with literature values obtained by the Hertzian indentation method. Furthermore, the measured elastic modulus for the TBC is lower than that reported for bulk ZrO{sub 2} ({approx} 190 GPa). This difference is believed to be due to the presence of a significant amount of porosity and microcracks in the TBCs. Hardness was also measured.
Size-dependent effective Young’s modulus of silicon nitride cantilevers
Babaei Gavan, K.; Westra, H.J.R.; Van der Drift, E.W.J.M.; Venstra, W.J.; Van der Zant, H.S.J.
2009-01-01
The effective Young’s modulus of silicon nitride cantilevers is determined for thicknesses in the range of 20–684 nm by measuring resonance frequencies from thermal noise spectra. A significant deviation from the bulk value is observed for cantilevers thinner than 150 nm. To explain the observations
Determination of Modulus of Elasticity and Shear Modulus by the Measurement of Relative Strains
Labašová, Eva
2016-12-01
This contribution is focused on determining the material properties (Young modulus and shear modulus) of the testing samples. The theoretical basis for determining material properties are the knowledge of linear elasticity and strength. The starting points are dependencies among the modulus of elasticity, shear modulus, normal stress and relative strain. The relative strains of the testing samples were obtained by measuring predefined load conditions using a strain-gauge bridge and the universal measurement system Quantum X MX 840. The integration of these tasks into the teaching process enhances practical and intellectual skills of students at secondary level technical universities.
Determination of Modulus of Elasticity and Shear Modulus by the Measurement of Relative Strains
Directory of Open Access Journals (Sweden)
Labašová Eva
2016-12-01
Full Text Available This contribution is focused on determining the material properties (Young modulus and shear modulus of the testing samples. The theoretical basis for determining material properties are the knowledge of linear elasticity and strength. The starting points are dependencies among the modulus of elasticity, shear modulus, normal stress and relative strain. The relative strains of the testing samples were obtained by measuring predefined load conditions using a strain-gauge bridge and the universal measurement system Quantum X MX 840. The integration of these tasks into the teaching process enhances practical and intellectual skills of students at secondary level technical universities.
Influence of substrate modulus on gecko adhesion
Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali
2017-01-01
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics). PMID:28287647
Influence of substrate modulus on gecko adhesion
Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali
2017-03-01
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).
Elastomer modulus and dielectric strength scaling with sample thickness
Larson, Kent
2015-04-01
Material characteristics such as adhesion and dielectric strength have well recognized dependencies on material thickness. There is disagreement, however, on the scale: the long held dictum that dielectric strength is inversely proportional to the square root of sample thickness has been shown to not always hold true for all materials, nor for all possible thickness regions. In D-EAP applications some studies have postulated a "critical thickness" below which properties show significantly less thickness dependency. While a great deal of data is available for dielectric strength, other properties are not nearly as well documented as samples get thinner. In particular, elastic modulus has been found to increase and elongation to decrease as sample thickness is lowered. This trend can be observed experimentally, but has been rarely reported and certainly does not appear in typical suppliers' product data sheets. Both published and newly generated data were used to study properties such as elastic modulus and dielectric strength vs sample thickness in silicone elastomers. Several theories are examined to explain such behavior, such as the impact of defect size and of common (but not well reported) concentration gradients that occur during elastomer curing that create micron-sized layers at the upper and lower interfaces with divergent properties to the bulk material. As Dielectric Electro-Active Polymer applications strive to lower and lower material thickness, changing mechanical properties must be recognized and taken into consideration for accurate electro-mechanical predictions of performance.
Measuring shear modulus of individual fibers
Behlow, Herbert; Saini, Deepika; Oliviera, Luciana; Skove, Malcolm; Rao, Apparao
2014-03-01
Fiber technology has advanced to new heights enabling tailored mechanical properties. For reliable fiber applications their mechanical properties must be well characterized at the individual fiber level. Unlike the tensile modulus, which can be well studied in a single fiber, the present indirect and dynamic methods of measuring the shear properties of fibers suffer from various disadvantages such as the interaction between fibers and the influence of damping. In this talk, we introduce a quasi-static method to directly measure the shear modulus of a single micron-sized fiber. Our simple and inexpensive setup yields a shear modulus of 16 and 2 GPa for a single IM7 carbon fiber and a Kevlar fiber, respectively. Furthermore, our setup is also capable of measuring the creep, hysteresis and the torsion coefficient, and examples of these will be presented.
Torres, Jessica M; Stafford, Christopher M; Vogt, Bryan D
2010-09-28
The mechanical stability of polymeric nanostructures is critical to the processing, assembly, and performance of numerous existing and emerging technologies. A key predictor of mechanical stability is the elastic modulus. However, a significant reduction in modulus has been reported for thin films and nanostructures when the thickness or size of the polymer material decreases below a critical length scale. Routes to mitigate or even eliminate this reduction in modulus, and thus enhancing the mechanically stability of polymeric nanostructures, would be extremely valuable. Here, two routes to modulate the mechanical properties of polymers at the nanoscale are described. Exposure to ultraviolet light and ozone (UVO) cross-links the near surface region of high molecular mass PS films, rendering the elastic modulus independent of thickness. However, UVO cannot eliminate the decrease in modulus of low molecular mass PS or PMMA due to limited reaction depth and photodegradation, respectively. Alternatively, the thickness dependence of the elastic modulus of both PS and PMMA can be eliminated by addition of dioctyl phthalate (DOP) at 5% by mass. Furthermore, an increase in modulus is observed for films with thicknesses less than 30 nm with 5% DOP by mass in comparison to neat PS. Although DOP acts as a plasticizer for both PS and PMMA in the bulk, evidence indicates that DOP acts as an antiplasticizer at the nanoscale. By maintaining or even increasing the elastic modulus of polymers at the nanoscale, these methods could lead to improved stability of polymeric nanostructures and devices.
Evaluation of Antenna Foundation Elastic Modulus
Mcginness, H.; Anderson, G.
1983-01-01
An experiment to measure the elastic deflection of the DSS 14 concrete pedestal under the weight of the antenna was conducted in February 1983 and is compared to a similiar experiment made in 1968. Comparison of the results confirms the decrease in elastic modulus measured on core samples recently taken from the pedestal.
Measuring Elastic Modulus of Sintered Metal
Fedors, R. F.; Eastman, A. F.
1983-01-01
Technique minimizes effect of substrate on thin sintered coating. Uniaxial tension test yields approximate value for elastic modulus of sintered material on thin substrate. Electrode composed of central perforated nickel plated steel sheet about 4 mils (0.1mm) thick, coated on each face by porous sintered nickel about 8 mils (0.2mm) thick.
Structural relaxation monitored by instantaneous shear modulus
DEFF Research Database (Denmark)
Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil
1998-01-01
This paper reports on aging of the silicone oil MS704 for sudden changes of temperature from 210.5 to 209.0 K and from 207.5 to 209.0 K studied by continuously monitoring the instantaneous shear modulus G [infinity]. The results are interpreted within the Tool-Narayanaswamy formalism with a reduced...
Analysis of bed joint influence on masonry modulus of elasticity
Zavalis, R.; Jonaitis, B.; Paulo B. Lourenço
2014-01-01
The means of determining the modulus of elasticity presented in technical literature often underestimate factors such as the influence of mechanical properties of the bed joint mortar and the influence of contact zone of the masonry unit and mortar on the elasticity modulus. Research carried out by the authors show that the modulus of elasticity of the bed joint considering influence of the contact zone (effective modulus of elasticity) is 3 to 25 times less than mortar modulus of...
Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer
2017-03-29
Article 3. DATES COVERED (From - To) 04 August 2016 – 29 March 2017 4. TITLE AND SUBTITLE Measuring Propellant Stress Relaxation Modulus Using Dynamic...ERC 14. ABSTRACT A method for determining the stress relaxation master curve of solid rocket propellants was developed. The propellant was tested in... stress relaxation modulus, Mpa; E∞ = long-term equilibrium modulus, Mpa; E0 = storage modulus, Mpa; E0 0 = loss modulus, Mpa; F = Fisher test
Young's modulus of peritubular and intertubular human dentin by nano-indentation tests.
Ziskind, Daniel; Hasday, Moran; Cohen, Sidney R; Wagner, H Daniel
2011-04-01
The local Young modulus of dry dentin viewed as a hierarchical composite was measured by nano-indentation using two types of experiments, both in a continuous stiffness measurement mode. First, tests were performed radially along straight lines running across highly mineralized peritubular dentin sections and through less mineralized intertubular dentin areas. These tests revealed a gradual decrease in Young's modulus from the bulk of the peritubular dentin region where modulus values of up to ∼40-42GPa were observed, down to approximately constant values of ∼17GPa in the intertubular dentin region. A second set of nano-indentation experiments was performed on the facets of an irregular polyhedron specimen cut from the intertubular dentin region, so as to probe the modulus of intertubular dentin specimens at different orientations relative to the tubular direction. The results demonstrated that the intertubular dentin region may be considered to be quasi-isotropic, with a slightly higher modulus value (∼22GPa) when the indenting tip axis is parallel to the tubular direction, compared to the values (∼18GPa) obtained when the indenting tip axis is perpendicular to the tubule direction. Copyright © 2010 Elsevier Inc. All rights reserved.
Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam
Energy Technology Data Exchange (ETDEWEB)
Kim, Nohyu; Yang, Seung Yong [School of Mechatronics Engineering, Korea University of Technology and Education, Cheonan (Korea, Republic of)
2016-02-15
The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method.
High Strength and High Modulus Electrospun Nanofibers
Jian Yao; Cees W. M. Bastiaansen; Ton Peijs
2014-01-01
Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents an in-depth review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength and high modulus nanofibers. As such, it aims to provide some guidance to future research activities in the area of high performance electrospun fibers.
Fibonacci difference sequence spaces for modulus functions
Directory of Open Access Journals (Sweden)
Kuldip Raj
2015-05-01
Full Text Available In the present paper we introduce Fibonacci difference sequence spaces l(F, Ƒ, p, u and l_∞(F, Ƒ, p, u by using a sequence of modulus functions and a new band matrix F. We also make an effort to study some inclusion relations, topological and geometric properties of these spaces. Furthermore, the alpha, beta, gamma duals and matrix transformation of the space l(F, Ƒ, p, u are determined.
Modulus for the coal ash. Summary
Energy Technology Data Exchange (ETDEWEB)
Rank, V.
1944-06-30
This summary outlined the procedure for obtaining a modulus to determine the effects of varying ash content. This modulus was to indicate the relative amounts of aluminum oxide and silicon dioxide after addition of alkalais or alkaline-earth constituents found in catalysts. The calculation of the modulus was based upon stoichiometric ratios of these oxides to other major components of ash as represented in the major minerals in the ash. The assumptions about the conditions in low- to intermediate-temperature coking included the following: (1) magnesium oxide was found only in biotite, which contained potassium oxide, magnesium oxide, aluminum oxide, silicon dioxide, and water in the respective mole ratios 1:4:2:6:1. (2) Potassium oxide outside of biotite was found only in muscovite, which contained potassium oxide, aluminum oxide, silicon dioxide, and water in the respective mole ratios 1:1:6:2. (3) Sodium oxide was combined only with aluminum oxide and silicon dioxide in the mole ratios 1:1:6. (4) Phosphoric acid was found as aluminum phosphate. (5) Lime was found in anortite, which contained calcium sulfate, calcium carbonate, or calcium oxide combined with aluminum oxide and silicon dioxide in the mole ratios 1:1:2. (6) Aluminum oxide and silicon dioxide existed mainly in the hydrated state with the two of them combined with water in the mole ratios 1:2:2. The completed formula for the modulus was given as M = (aluminum oxide) + (silicon dioxide) - 0.65(magnesium oxide) - 4.90(potassium oxide + sodium oxide) - 3.96(calcium oxide) - 0.72(phosphorous pentoxide), where the parentheses should be filled by numbers in weight units for the respective compounds.
Asphalt mix characterization using dynamic modulus and APA testing.
2005-11-01
final report summarizes two research efforts related to asphalt mix characterization: dynamic modulus and Asphalt Pavement Analyzer testing. One phase of the research consisted of a laboratory-based evaluation of dynamic modulus of Oregon dense-grade...
Directory of Open Access Journals (Sweden)
S. K. Deb Nath
2017-10-01
Full Text Available Using molecular dynamics simulation, tension and bending tests of a Fe nanopillar are carried out to obtain its Young’s modulus and yield strength. Then the comparative study of Young’s modulus and yield strength of a Fe nanopillar under bending and tension are carried out varying its diameter in the range of diameter 1-15nm. We find out the reasons why bending Young’s modulus and yield strength of a Fe nanopillar are higher than those of tension Young’s modulus and yield strength of a Fe nanopillar. Using the mobility parameters of bulk Fe from the experimental study [N. Urabe and J. Weertman, Materials Science and Engineering 18, 41 (1975], its temperature dependent stress-strain relationship, yield strength and strain hardening modulus are obtained from the dislocation dynamics simulations. Strain rate dependent yield strength and strain hardening modulus of bulk Fe pillars under tension are studied. Temperature dependent creep behaviors of bulk Fe pillars under tension are also studied. To verify the soundness of the present dislocation dynamics studies of the mechanical properties of bulk Fe pillars under tension, the stress vs. strain relationship and dislocation density vs. strain of bulk Fe pillars obtained by us are compared with the published results obtained by S. Queyreau, G. Monnet, and B. Devincre, International Journal of Plasticity 25, 361 (2009.
Nath, S. K. Deb
2017-10-01
Using molecular dynamics simulation, tension and bending tests of a Fe nanopillar are carried out to obtain its Young's modulus and yield strength. Then the comparative study of Young's modulus and yield strength of a Fe nanopillar under bending and tension are carried out varying its diameter in the range of diameter 1-15nm. We find out the reasons why bending Young's modulus and yield strength of a Fe nanopillar are higher than those of tension Young's modulus and yield strength of a Fe nanopillar. Using the mobility parameters of bulk Fe from the experimental study [N. Urabe and J. Weertman, Materials Science and Engineering 18, 41 (1975)], its temperature dependent stress-strain relationship, yield strength and strain hardening modulus are obtained from the dislocation dynamics simulations. Strain rate dependent yield strength and strain hardening modulus of bulk Fe pillars under tension are studied. Temperature dependent creep behaviors of bulk Fe pillars under tension are also studied. To verify the soundness of the present dislocation dynamics studies of the mechanical properties of bulk Fe pillars under tension, the stress vs. strain relationship and dislocation density vs. strain of bulk Fe pillars obtained by us are compared with the published results obtained by S. Queyreau, G. Monnet, and B. Devincre, International Journal of Plasticity 25, 361 (2009).
Nondestructive Measurement of Dynamic Modulus for Cellulose Nanofibril Films
Yan Qing; Robert J. Ross; Zhiyong Cai; Yiqiang Wu
2013-01-01
Nondestructive evaluation of cellulose nanofibril (CNF) films was performed using cantilever beam vibration (CBV) and acoustic methods to measure dynamic modulus. Static modulus was tested using tensile tension method. Correlation analysis shows the data measured by CBV has little linear relationship with static modulus, possessing a correlation coefficient (R
Directory of Open Access Journals (Sweden)
Ibrahim Dauda Muhammad
2015-01-01
Full Text Available The single-walled zirconia nanotube is structurally modeled and its Young’s modulus is valued by using the finite element approach. The nanotube was assumed to be a frame-like structure with bonds between atoms regarded as beam elements. The properties of the beam required for input into the finite element analysis were computed by connecting energy equivalence between molecular and continuum mechanics. Simulation was conducted by applying axial tensile strain on one end of the nanotube while the other end was fixed and the corresponding reaction force recorded to compute Young’s modulus. It was found out that Young’s modulus of zirconia nanotubes is significantly affected by some geometrical parameters such as chirality, diameter, thickness, and length. The obtained values of Young’s modulus for a certain range of diameters are in agreement with what was obtained in the few experiments that have been conducted so far. This study was conducted on the cubic phase of zirconia having armchair and zigzag configuration. The optimal diameter and thickness were obtained, which will assist in designing and fabricating bulk nanostructured components containing zirconia nanotubes for various applications.
A simple model for calculating the bulk modulus of the mixed ionic ...
Indian Academy of Sciences (India)
Bb; 61.72.J- ; 62.20.D- ; 66.30.Fq; 66.30.−h. 1. Introduction. Ammonium halides are dimorphic, crystallizing in the CsCl-type crystal structure at low temperatures and in the NaCl-type crystal structure at high temperatures, with the excep- tion of NH4F, which crystallizes in the ZnS-type lattice [1,2]. The ammonium halides are.
On the realization of the bulk modulus bounds for two-phase viscoelastic composites
DEFF Research Database (Denmark)
Andreasen, Casper Schousboe; Andreassen, Erik; Jensen, Jakob Søndergaard
2014-01-01
Materials with good vibration damping properties and high stiffness are of great industrial interest. In this paper the bounds for viscoelastic composites are investigated and material microstructures that realize the upper bound are obtained by topology optimization. These viscoelastic composites...... can be realized by additive manufacturing technologies followed by an infiltration process. Viscoelastic composites consisting of a relatively stiff elastic phase, e.g. steel, and a relatively lossy viscoelastic phase, e.g. silicone rubber, have non-connected stiff regions when optimized for maximum...... damping. In order to ensure manufacturability of such composites the connectivity of the matrix is ensured by imposing a conductivity constraint and the influence on the bounds is discussed. © 2013 Elsevier Ltd. All rights reserved....
1978-01-01
T Y Ct ., A ’ .’. I r ICA T I t > N Or T~ e I ’ P A r t (Ilk. ... ..~~.. l’nter. ,l) REPORT DOCU,~%ENTAT ION PAGE F .) ~~~~PORT N ~~~~‘,,.,__,. 2...I O N NAME AND A D D R E S S 10. P R O G R A M E L E M E,~l T , PROJ E CT TA S, ( M i d w e s t Research I n s t i t u t e A R E A S W O R K / P...the same time, The coil for tap water is used pr imar ily to hasten cooling of the bath. The bath liquid temperature is measured by ASTM extended—range
Dynamic modulus of nanosilica modified porous asphalt
Arshad, A. K.; Masri, K. A.; Ahmad, J.; Samsudin, M. S.
2017-11-01
Porous asphalt (PA) is a flexible pavement layer with high interconnected air void contents and constructed using open-graded aggregates. Due to high temperature environment and increased traffic volume in Malaysia, PA may have deficiencies particularly in rutting and stiffness of the mix. A possible way to improve these deficiencies is to improve the asphalt binder used. Binder is normally modified using polymer materials to improve its properties. However, nanotechnology presently is being gradually used for asphalt modification. Nanosilica (NS), a byproduct of rice husk and palm oil fuel ash is used as additive in this study. The aim of this study is to enhance the rutting resistance and stiffness performance of PA using NS. This study focused on the performance of PA in terms of dynamic modulus with the addition of NS modified binder to produce better and more durable PA. From the result of Dynamic SPT Test, it shows that the addition of NS was capable in enhancing the stiffness and rutting resistance of PA. The addition of NS also increase the dynamic modulus value of PA by 50%.
National Research Council Canada - National Science Library
Yasser Zare
2016-01-01
.... The properties of pseudoparticles are determined in some samples by the experimental data of Young's modulus and the roles of pseudoparticles in the shear, bulk, and Young's moduli of nanocomposites are discussed...
19 CFR 149.4 - Bulk and break bulk cargo.
2010-04-01
... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from the...
Directory of Open Access Journals (Sweden)
Holmes Amey J
2005-07-01
Full Text Available Abstract Background Bronchial hyperreactivity is influenced by properties of the conducting airways and the surrounding pulmonary parenchyma, which is tethered to the conducting airways. Vitamin A deficiency (VAD is associated with an increase in airway hyperreactivity in rats and a decrease in the volume density of alveoli and alveolar ducts. To better define the effects of VAD on the mechanical properties of the pulmonary parenchyma, we have studied the elastic modulus, elastic fibers and elastin gene-expression in rats with VAD, which were supplemented with retinoic acid (RA or remained unsupplemented. Methods Parenchymal mechanics were assessed before and after the administration of carbamylcholine (CCh by determining the bulk and shear moduli of lungs that that had been removed from rats which were vitamin A deficient or received a control diet. Elastin mRNA and insoluble elastin were quantified and elastic fibers were enumerated using morphometric methods. Additional morphometric studies were performed to assess airway contraction and alveolar distortion. Results VAD produced an approximately 2-fold augmentation in the CCh-mediated increase of the bulk modulus and a significant dampening of the increase in shear modulus after CCh, compared to vitamin A sufficient (VAS rats. RA-supplementation for up to 21 days did not reverse the effects of VAD on the elastic modulus. VAD was also associated with a decrease in the concentration of parenchymal elastic fibers, which was restored and was accompanied by an increase in tropoelastin mRNA after 12 days of RA-treatment. Lung elastin, which was resistant to 0.1 N NaOH at 98°, decreased in VAD and was not restored after 21 days of RA-treatment. Conclusion Alterations in parenchymal mechanics and structure contribute to bronchial hyperreactivity in VAD but they are not reversed by RA-treatment, in contrast to the VAD-related alterations in the airways.
Young's Modulus of bilayer Silicene Nanoribbons
Meza-Montes, Lilia; Chávez-Castillo, M. R.; Rodríguez-Meza, M. A.
Mechanical properties of Silicene Nanoribbons (SNRs) are determined by their width and chirality, and can be also be modified by the presence of vacancy defects. In the case of bilayer SNRs, interlayer interactions influence its physical properties. We report results, at room temperature, on the Young's Modulus (YM) of pristine and monovacancy defective bilayers of SNRs. Molecular dynamics simulations were performed using the EDIP potential. YM increases with SNRs length, depends on chirality, the number and location of vacancies. Distance between layers is also important. These results are discussed in terms of missing bonds. Atomic stress distributions for defective bilayer SNRs show a larger stress concentration around the vacancy defect. Besides, if only the second layer has a mono-vacancy at its center, a larger stress concentration is observed on the atom located just below the vacancy defect. Thus, the bilayer structure carries less strain and it can be easily deformed. Partially supported by VIEP-BUAP, Mexico.
A constrained modulus reconstruction technique for breast cancer assessment.
Samani, A; Bishop, J; Plewes, D B
2001-09-01
A reconstruction technique for breast tissue elasticity modulus is described. This technique assumes that the geometry of normal and suspicious tissues is available from a contrast-enhanced magnetic resonance image. Furthermore, it is assumed that the modulus is constant throughout each tissue volume. The technique, which uses quasi-static strain data, is iterative where each iteration involves modulus updating followed by stress calculation. Breast mechanical stimulation is assumed to be done by two compressional rigid plates. As a result, stress is calculated using the finite element method based on the well-controlled boundary conditions of the compression plates. Using the calculated stress and the measured strain, modulus updating is done element-by-element based on Hooke's law. Breast tissue modulus reconstruction using simulated data and phantom modulus reconstruction using experimental data indicate that the technique is robust.
Interfacial Modulus Mapping during Structural Transformation in Shape Memory Alloys
Wan, Jianfeng; Cui, Shushan; Zhang, Jihua; Rong, Yonghua
2017-10-01
Through the modified phase-field model the local soft mode mechanism of nucleation during martensitic transformation was confirmed in shape memory alloys. It was discovered that the modulus loss (8 pct) depended on the martensitic nucleation exceeding the loss (1 pct) during the martensitic growth. The elastic modulus and the stress across the martensite/parent interface differed from those across the martensitic twin boundary. The modulus losses in systems with three variants, two variants, and one variant were compared.
Elastic properties of Pd40Cu30Ni10P20 bulk glass in supercooled liquid region
DEFF Research Database (Denmark)
Nishiyama, N.; Inoue, A.; Jiang, Jianzhong
2001-01-01
In situ ultrasonic measurements for the Pd40Cu30Ni10P20 bulk glass in three states: Glassy solid, supercooled liquid, and crystalline, have been performed. It is found that velocities of both longitudinal and transverse waves and elastic moduli (shear modulus, bulk modulus, Young's modulus......, and Lame parameter), together with Debye temperature, gradually decrease with increasing temperature through the glass transition temperature as the Poisson's ratio increases. The behavior of the velocity of transverse wave vs. temperature in the supercooled liquid region could be explained by viscosity...
DEFF Research Database (Denmark)
Hecksher, Tina; Olsen, Niels Boye; Nelson, Keith Adam
2013-01-01
We present dynamic shear and bulk modulus measurements of supercooled tetraphenyl-tetramethyl-trisiloxane (DC704) and 5-phenyl-4-ether over a range of temperatures close to their glass transition. The data are analyzed and compared in terms of time-temperature superposition (TTS), the relaxation...... time, and the spectral shape parameters. We conclude that TTS is obeyed to a good approximation for both the bulk and shear moduli. The loss-peak shapes are nearly identical, while the shear modulus relaxes faster than the bulk modulus. The temperature dependence of this decoupling of time scales...
Elastic modulus in the selection of interbody implants.
Heary, Robert F; Parvathreddy, Naresh; Sampath, Sujitha; Agarwal, Nitin
2017-06-01
The modulus of elasticity of an assortment of materials used in spinal surgery, as well as cortical and cancellous bones, is determined by direct measurements and plotting of the appropriate curves. When utilized in spine surgery, the stiffness of a surgical implant can affect its material characteristics. The modulus of elasticity, or Young's modulus, measures the stiffness of a material by calculating the slope of the material's stress-strain curve. While many papers and presentations refer to the modulus of elasticity as a reason for the choice of a particular spinal implant, no peer-reviewed surgical journal article has previously been published where the Young's modulus values of interbody implants have been measured. Materials were tested under pure compression at the rate of 2 mm/min. A maximum of 45 kilonewtons (kN) compressive force was applied. Stress-strain characteristics under compressive force were plotted and this plot was used to calculate the elastic modulus. The elastic modulus calculated for metals was more than 50 Gigapascals (GPa) and had significantly higher modulus values compared to poly-ether-ether-ketone (PEEK) materials and allograft bone. The data generated in this paper may facilitate surgeons to make informed decisions on their choices of interbody implants with specific attention to the stiffness of the implant chosen.
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
Using a generalized spherical mean operator, we define generalized modulus of smoothness in the space L k 2 ( R d ) . Based on the Dunkl operator we define Sobolev-type space and -functionals. The main result of the paper is the proof of the equivalence theorem for a -functional and a modulus of smoothness for the ...
Generalized Vector-Valued Sequence Spaces Defined by Modulus Functions
Directory of Open Access Journals (Sweden)
Işik Mahmut
2010-01-01
Full Text Available We introduce the vector-valued sequence spaces , , and , and , using a sequence of modulus functions and the multiplier sequence of nonzero complex numbers. We give some relations related to these sequence spaces. It is also shown that if a sequence is strongly -Cesàro summable with respect to the modulus function then it is -statistically convergent.
Koch, C. C.; Langdon, T. G.; Lavernia, E. J.
2017-11-01
This paper will address three topics of importance to bulk nanostructured materials. Bulk nanostructured materials are defined as bulk solids with nanoscale or partly nanoscale microstructures. This category of nanostructured materials has historical roots going back many decades but has relatively recent focus due to new discoveries of unique properties of some nanoscale materials. Bulk nanostructured materials are prepared by a variety of severe plastic deformation methods, and these will be reviewed. Powder processing to prepare bulk nanostructured materials requires that the powders be consolidated by typical combinations of pressure and temperature, the latter leading to coarsening of the microstructure. The thermal stability of nanostructured materials will also be discussed. An example of bringing nanostructured materials to applications as structural materials will be described in terms of the cryomilling of powders and their consolidation.
Modulus of Elasticity and Thermal Expansion Coefficient of ITO Film
Energy Technology Data Exchange (ETDEWEB)
Carter, Austin D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elhadj, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-06-24
The purpose of this experiment was to determine the modulus of elasticity (E) and thermal expansion coefficient (α) of RF sputtered Indium Tin Oxide (ITO) as a function of temperature (T), and to collect ITO film stress data. In order to accomplish that goal, the Toho FLX-2320-S thin film stress measurement machine was used to collect both single stress and stress-temperature data for ITO coated fused silica and sapphire substrates. The stress measurement function of the FLX-2320-S cannot be used to calculate the elastic modulus of the film because the Stoney formula incorporates the elastic modulus of the substrate, rather than of the film itself.
Directory of Open Access Journals (Sweden)
Luiz Claudio Pardini
2002-10-01
Full Text Available Carbon fibres and glass fibres are reinforcements for advanced composites and the fiber strength is the most influential factor on the strength of the composites. They are essentially brittle and fail with very little reduction in cross section. Composites made with these fibres are characterized by a high strength/density ratio and their properties are intrisically related to their microstructure, i.e., amount and orientation of the fibres, surface treatment, among other factors. Processing parameters have an important role in the fibre mechanical behaviour (strength and modulus. Cracks, voids and impurities in the case of glass fibres and fibrillar misalignments in the case of carbon fibres are created during processing. Such inhomogeneities give rise to an appreciable scatter in properties. The most used statistical tool that deals with this characteristic variability in properties is the Weibull distribution. The present work investigates the influence of the testing gage length on the strength, Young's modulus and Weibull modulus of carbon fibres and glass fibres. The Young's modulus is calculated by two methods: (i ASTM D 3379M, and (ii interaction between testing equipment/specimen The first method resulted in a Young modulus of 183 GPa for carbon fibre, and 76 GPa for glass fibre. The second method gave a Young modulus of 250 GPa for carbon fibre and 50 GPa for glass fibre. These differences revelead differences on how the interaction specimen/testing machine can interfere in the Young modulus calculations. Weibull modulus can be a tool to evaluate the fibre's homogeneity in terms of properties and it is a good quality control parameter during processing. In the range of specimen gage length tested the Weibull modulus for carbon fibre is ~ 3.30 and for glass fibres is ~ 5.65, which indicates that for the batch of fibres tested, the glass fibre is more uniform in properties.
Elasticity modulus and damping ratio of macaw palm rachillas
National Research Council Canada - National Science Library
Villar, Flora Maria de Melo; Pinto, Francisco de Assis de Carvalho; Santos, Fábio Lúcio; Grossi, José Antônio Saraiva; Velloso, Nara Silveira
2017-01-01
.... Thus, this study seeks to determine the modulus of elasticity and the damping ratio of four different plant accessions obtained from the Active Germplasm Bank of the Universidade Federal de Viçosa (UFV...
Frequency-dependent complex modulus of the uterus: preliminary results
Energy Technology Data Exchange (ETDEWEB)
Kiss, Miklos Z [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Hobson, Maritza A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Varghese, Tomy [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Harter, Josephine [Department of Surgical Pathology, University of Wisconsin, Madison, WI 53706 (United States); Kliewer, Mark A [Department of Radiology, University of Wisconsin, Madison, WI 53706 (United States); Hartenbach, Ellen M [Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53706 (United States); Zagzebski, James A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States)
2006-08-07
The frequency-dependent complex moduli of human uterine tissue have been characterized. Quantification of the modulus is required for developing uterine ultrasound elastography as a viable imaging modality for diagnosing and monitoring causes for abnormal uterine bleeding and enlargement, as well assessing the integrity of uterine and cervical tissue. The complex modulus was measured in samples from hysterectomies of 24 patients ranging in age from 31 to 79 years. Measurements were done under small compressions of either 1 or 2%, at low pre-compression values (either 1 or 2%), and over a frequency range of 0.1-100 Hz. Modulus values of cervical tissue monotonically increased from approximately 30-90 kPa over the frequency range. Normal uterine tissue possessed modulus values over the same range, while leiomyomas, or uterine fibroids, exhibited values ranging from approximately 60-220 kPa.
Resilient Modulus Characterization of Compacted Cohesive Subgrade Soil
Directory of Open Access Journals (Sweden)
Wojciech Sas
2017-04-01
Full Text Available Soil investigations concerning cyclic loading focus on the evaluation, in particular, of design parameters, such as elastic modulus, Poisson’s ratio, or resilient modulus. Structures subjected to repeated loading are vulnerable to high deformations, especially when subgrade soils are composed of cohesive, fully-saturated soils. Such subgrade soils in the eastern part of Europe have a glacial genesis and are a mix of sand, silt, and clay fractions. The characteristic of, e.g., Young modulus variation and resilient modulus from repeated loading tests, is presented. Based on performed resonant column and cyclic triaxial tests, an analytical model is proposed. The model takes into consideration actual values of effective stress p′, as well as loading characteristics and the position of the effective stress path. This approach results in better characterization of pavement or industrial foundation systems based on the subgrade soil in undrained conditions. The recoverable strains characterized by the resilient modulus Mr value in the first cycle of loading was between 44 MPa and 59 MPa for confining pressure σ’3 equal to 45 kPa, and between 48 MPa and 78 MPa for σ’3 equal to 90 kPa. During cyclic loading, cohesive soil, at first, degrades. When pore pressure reaches equilibrium, the resilient modulus value starts to increase. The above-described phenomena indicate that, after the plastic deformation caused by excessive load and excess pore water pressure dissipation, the soil becomes resilient.
Heat transport in bulk/nanoporous/bulk silicon devices
Energy Technology Data Exchange (ETDEWEB)
Criado-Sancho, M. [Departamento de Ciencias y Técnicas Físicoquimicas, Facultad de Ciencias, UNED, Senda del Rey 9, 20040 Madrid (Spain); Jou, D., E-mail: David.Jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)
2013-02-04
We study heat transport in bulk/nanoporous/bulk silicon devices; we show that, despite bulk/nanoporous devices may act as thermal rectifiers, the non-linear aspects of their joint thermal conductance are not strong enough to lead to a negative differential thermal resistance, necessary to allow bulk/nanoporous/bulk Si devices to act as thermal transistors. Furthermore, we explicitly study the effective thermal conductivity of the mentioned devices for several temperatures, geometries, porosities, and pore size.
"Understanding" cosmological bulk viscosity
Zimdahl, Winfried
1996-01-01
A universe consisting of two interacting perfect fluids with the same 4-velocity is considered. A heuristic mean free time argument is used to show that the system as a whole cannot be perfect as well but neccessarily implies a nonvanishing bulk viscosity. A new formula for the latter is derived and compared with corresponding results of radiative hydrodynamics.
Haveren, van J.; Scott, E.L.; Sanders, J.P.M.
2008-01-01
Given the current robust forces driving sustainable production, and available biomass conversion technologies, biomass-based routes are expected to make a significant impact on the production of bulk chemicals within 10 years, and a huge impact within 20-30 years. In the Port of Rotterdam there is a
Shear modulus reconstruction by ultrasonically measured strain ratio.
Sumi, Chikayoshi; Matsuzawa, Hidenori
2007-12-01
In addition to a description of our three previously developed one-dimensional (1D) methods from the viewpoint of shear modulus reconstruction using the strain ratio, two new methods for stabilizing the 1D methods are described, together with their limitations. As confirmed using human in vivo breast tissues, method 1 for evaluating the strain ratio itself is useful when the measurement accuracy of the strain distribution is high. However, because tissues having high shear moduli, such as scirrhous carcinoma, often form singular points/regions, both methods 2 and 3 using the strain ratio (initial estimate) and a regularization method are effective for realizing a unique, stable, useful shear modulus reconstruction. Because method 3 carries out implicit integration only at singular points/regions, whereas method 2 carries out implicit integration throughout the region of interest (ROI), the smaller number of singular points enables more rapid shear modulus reconstruction by method 3 than by method 2. Like method 1, method 3 is also useful when the measurement accuracy of the strain distribution is high. However, when evaluating strain distribution in an ROI with a high spatial resolution to obtain a shear modulus reconstruction having a high spatial resolution, shear modulus reconstructions obtained by methods 1, 2, and 3 often become laterally unstable due to the instability and low accuracy of the strains in the reference regions (reference strains), i.e., regularization in methods 2 and 3 cannot reduce the instability in the initial estimate. To cope with this instability, (i) the reconstruction obtained by calculating the strain ratio should be low-pass filtered; for breast tissues, in particular, the reconstruction of the inverse shear modulus should be low-pass filtered, not the reconstruction of the shear modulus. (ii) Otherwise, when using homogeneous regions as a reference, such as a block of reference material, fatty tissue, or parenchyma, evaluation of
Research on Fatigue Strain and Fatigue Modulus of Concrete
Directory of Open Access Journals (Sweden)
Fangping Liu
2017-01-01
Full Text Available Concrete fatigue strain and fatigue modulus evolution play a vital role in the evaluation of the material properties. In this paper, by analyzing the advantages and disadvantages of existing concrete strain analysis methods, the level-S nonlinear fatigue strain model was proposed. The parameters’ physical meaning, the ranges, and the impact on the shape of the curve were all discussed. Then, the evolution model of fatigue modulus was established based on the fatigue strain evolution model and the hypothesis of fatigue modulus inversely related fatigue strain amplitude. The results indicate that the level-S model covered all types of fatigue strain evolution. It is very suitable for the description of strain evolution of concrete for its strong adaptability and high accuracy. It was found that the fitting curves coincided with the experimental curves very well, and the correlation coefficients were all above 0.98. The evolution curves of fatigue strain modulus both have three stages, namely, variation phase, linear change stage, and convergence stage. The difference is that the fatigue strain evolution curve is from the lower left corner to the upper right corner, but the fatigue modulus evolution curve is from the upper left corner to the right lower corner.
Crack arrest within teeth at the dentinoenamel junction caused by elastic modulus mismatch.
Bechtle, Sabine; Fett, Theo; Rizzi, Gabriele; Habelitz, Stefan; Klocke, Arndt; Schneider, Gerold A
2010-05-01
Enamel and dentin compose the crowns of human teeth. They are joined at the dentinoenamel junction (DEJ) which is a very strong and well-bonded interface unlikely to fail within healthy teeth despite the formation of multiple cracks within enamel during a lifetime of exposure to masticatory forces. These cracks commonly are arrested when reaching the DEJ. The phenomenon of crack arrest at the DEJ is described in many publications but there is little consensus on the underlying cause and mechanism. Explanations range from the DEJ having a larger toughness than both enamel and dentin up to the assumption that not the DEJ itself causes crack arrest but the so-called mantle dentin, a thin material layer close to the DEJ that is somewhat softer than the bulk dentin. In this study we conducted 3-point bending experiments with bending bars consisting of the DEJ and surrounding enamel and dentin to investigate crack propagation and arrest within the DEJ region. Calculated stress intensities around crack tips were found to be highly influenced by the elastic modulus mismatch between enamel and dentin and hence, the phenomenon of crack arrest at the DEJ could be explained accordingly via this elastic modulus mismatch. Copyright 2010 Elsevier Ltd. All rights reserved.
Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi
2017-03-31
The purpose of this study was to investigate the depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites. Depth of cure and flexural properties were determined according to ISO 4049, and volumetric shrinkage was measured using a dilatometer. The depths of cure of giomers were significantly lower than those of resin composites, regardless of photo polymerization times. No difference in flexural strength and modulus was found among either high or low viscosity bulk fill materials. Volumetric shrinkage of low and high viscosity bulk-fill resin composites was significantly less than low and high viscosity giomers. Depth of cure of both low and high viscosity bulk-fill materials is time dependent. Flexural strength and modulus of high viscosity or low viscosity bulk-fill giomer or resin composite materials are not different for their respective category. Resin composites exhibited less polymerization shrinkage than giomers.
Determination of Young's Modulus of Graphene by Raman Spectroscopy
Lee, Jae-Ung; Yoon, Duhee; Cheong, Hyeonsik
2012-02-01
The mechanical properties of graphene are interesting research subjects because its Young's modulus and strength are extremely high. Values of ˜1 TPa for the Young's modulus have been reported [Lee et al. Science, 321, 385 (2008), Koenig et al. Nat. Nanotech. 6, 543 (2011)]. We made a graphene sample on a SiO2/Si substrate with closed-bottom holes by mechanical exfoliation. A pressure difference across the graphene membrane was applied by putting the sample in a vacuum chamber. This pressure difference makes the graphene membrane bulge upward like a balloon. By measuring the shifts of the Raman G and 2D bands, we estimated the amount of strain on the graphene membrane. By comparing the strain estimated from the Raman measurements with numerical simulations based on the finite element method, we obtained the Young's modulus of graphene.
Nano-fillers to tune Young's modulus of silicone matrix
Xia, Lijin; Xu, Zhonghua; Sun, Leming; Caveney, Patrick M.; Zhang, Mingjun
2013-04-01
In this study, we investigated nanoparticles, nanofibers, and nanoclays for their filler effects on tuning the Young's modulus of silicone matrix, a material with broad in vivo applications. Nano-fillers with different shapes, sizes, and surface properties were added into silicone matrix, and then their filler effects were evaluated through experimental studies. It was found that spherical nanoparticles could clearly improve Young's modulus of the silicone matrix, while nanoclays and carbon nanofibers had limited effects. Smaller spherical nanoparticles were better in performance compared to larger nanoparticles. In addition, enhanced distribution of the nanoparticles in the matrix has been observed to improve the filler effect. In order to minimize toxicity of the nanoparticles for in vivo applications, spherical nanoparticles coated with amine, acid, or hydroxide groups were also investigated, but they were found only to diminish the filler effect of nanoparticles. This study demonstrated that spherical nanoparticles could serve as fillers to tune Young's modulus of silicone matrix for potential applications in medicine.
Determination of the elastic modulus of snow via acoustic measurements
Gerling, Bastian; van Herwijnen, Alec; Löwe, Henning
2016-04-01
The elastic modulus of snow is a key quantity from the viewpoint of avalanche research and forecasting, snow engineering or materials science in general. Since it is a fundamental property, many measurements have been reported in the literature. Due to differences in measurement methods, there is a lot of variation in the reported values. Especially values derived via computer tomography (CT) based numerical calculations using finite element methods are not corresponding to the results of other methods. The central issue is that CT based moduli are purely elastic whereas other methods may include viscoelastic deformation. In order to avoid this discrepancy we derived the elastic modulus of snow via wave propagation measurements and compared our results with CT based calculations. We measured the arrival times of acoustic pulses propagating through the snow samples to determine the P-wave velocity and in turn derive the elastic modulus along the direction of wave propagation. We performed a series of laboratory experiments to derive the P-wave modulus of snow in relation to density. The P-wave modulus ranged from 10 to 280 MPa for a snow density between 150 and 370 kg/m^3;. The moduli derived from the acoustic measurements correlated well with the CT-based values and both exhibited a power law trend over the entire density range. Encouraged by these results we used the acoustic method to investigate the temporal evolution of the elastic modulus. The rate of increase was very close to values mentioned in literature on the sintering rate of snow. Overall, our results are a first but important step towards a new measurement method to attain the elastic properties of snow.
Temperature, Frequency and Young’s Modulus of a Wineglass
Directory of Open Access Journals (Sweden)
Amitta Miller
2015-01-01
Full Text Available A crystal soda-lime wineglass, heated to temperatures ranging from 25 °C to 150 °C, was tapped and the frequency recorded. It was shown that the relative change in the frequency at different temperatures can be used to determine the effect of temperature on Young’s Modulus of the glass. This simple method of tapping a wineglass is proposed as an effective way of determining the relative effect of temperature on Young’ Modulus of glass.
New insights into the Young's modulus of staggered biological composites.
Bar-On, Benny; Wagner, H Daniel
2013-03-01
This communication presents a simplified "mechanics-of-materials" approach for describing the mechanics of staggered composite architectures, such as those arising in a variety of biological tissues. This analysis calculates the effective modulus of the bio-composite and provides physical insights into its elastic behavior. Simplified expressions for high- and low-mineralized tissues are then proposed and the effects of the mineral thickness ratio and aspect ratio on the modulus are demonstrated. Copyright © 2012 Elsevier B.V. All rights reserved.
Young modulus dependence of nanoscopic friction coefficient in hard coatings
Riedo, E.; Brune, H.
2003-01-01
We present an atomic force microscope study of nanoscopic sliding friction on diamond, diamond-like carbon, and on three CrN thin films with varying hardness obtained by different growth temperatures. For the CrN films, we show that the changes in the friction coefficient can be traced back to variations of the Young modulus. More generally, we show for all samples investigated and in wearless regime, that the nanoscopic friction coefficient is directly linked to the Young modulus. (C) 2003 A...
DEFF Research Database (Denmark)
Schulz, Alexander
2015-01-01
symplasmic pathway from mesophyll to sieve elements. Crucial for the driving force is the question where water enters the pre-phloem pathway. Surprisingly, the role of PD in water movement has not been addressed so far appropriately. Modeling of assimilate and water fluxes indicates that in symplasmic...... the concentration gradient or bulk flow along a pressure gradient. The driving force seems to depend on the mode of phloem loading. In a majority of plant species phloem loading is a thermodynamically active process, involving the activity of membrane transporters in the sieve-element companion cell complex. Since...... is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...
DEFF Research Database (Denmark)
Schulz, Alexander
2015-01-01
is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...... the concentration gradient or bulk flow along a pressure gradient. The driving force seems to depend on the mode of phloem loading. In a majority of plant species phloem loading is a thermodynamically active process, involving the activity of membrane transporters in the sieve-element companion cell complex. Since...... assimilate movement includes an apoplasmic step, this mode is called apoplasmic loading. Well established is also the polymer-trap loading mode, where the phloem-transport sugars are raffinose-family oligomers in herbaceous plants. Also this mode depends on the investment of energy, here for sugar...
Giomataris, Ioanis; Andriamonje, Samuel A; Aune, S; Charpak, Georges; Colas, P; Giganon, Arnaud; Rebourgeard, P C; Salin, P; Rebourgeard, Ph.
2006-01-01
In this paper we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the PCB (Printed Circuit Board) technology is employed to produce the entire sensitive detector. Such fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robustness of the electrode materials will make it extremely attractive for several applications ranging from particle physics and astrophysics to medicine
Energy Technology Data Exchange (ETDEWEB)
Giomataris, I. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France)]. E-mail: ioa@hep.saclay.cea.fr; De Oliveira, R. [CERN, Geneva (Switzerland); Andriamonje, S. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Aune, S. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Charpak, G. [CERN, Geneva (Switzerland); Colas, P. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Fanourakis, G. [Institute of Nuclear Physcis, NCSR Demokritos, Aghia Paraskevi 15310 (Greece); Ferrer, E. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Giganon, A. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Rebourgeard, Ph. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Salin, P. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France)
2006-05-10
In this paper, we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the Printed Circuit Board (PCB) technology is employed to produce the entire sensitive detector. Such a fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robustness of the electrode materials will make it attractive for several applications ranging from particle physics and astrophysics to medicine.
Study on strength, elastic modulus of artifical lightweight aggregate concrete
Kakizaki, M.
1982-04-01
Aggregate strength of artificial lightweight concrete and concrete used with this artificial lightweight aggregate can be expected to have nearly the same strength as normal weight concrete. An experimental study of properties of concrete strength and correlation between compressive and tensile and flexural strengths and elastic modulus of its concrete was made.
Determination of the modulus of elasticity of the human cornea.
Elsheikh, Ahmed; Wang, Defu; Pye, David
2007-10-01
To determine the material behavior of the human cornea in the form of simple relationships between the modulus of elasticity and intraocular pressure (IOP) and to establish the effect of age on the material behavior. Human corneal specimens with age between 50 and 95 years were tested under inflation conditions to determine their behavior. The corneas were subjected to two extreme load rates to represent dynamic and static loading conditions. The pressure-deformation results were analyzed using shell theory to derive the relationship between the modulus of elasticity and IOP. The corneas demonstrated a nonlinear hyperelastic behavior pattern with an initial low stiffness stage and a final high stiffness stage. Despite the nonlinearity of the pressure deformation results, the relationship between the modulus of elasticity and the applied pressure was almost linear. A considerable increase was noted in the values of the modulus of elasticity associated with both age and load rate. General equations were derived to calculate the values of the secant and tangent moduli of elasticity in terms of IOP for any age greater than 50 years, and these equations are presented in a simple form suitable for use in numerical simulations. Adequate representation of corneal material behavior is essential for the accurate predictive modeling of corneal biomechanics. The material models developed in this work could be implemented in numerical simulations of refractive surgery procedures, corneal shape changes due to contact lens wear, and other applications.
Quantitative photoacoustic elastography of Young's modulus in humans
Hai, Pengfei; Zhou, Yong; Gong, Lei; Wang, Lihong V.
2017-03-01
Elastography can noninvasively map the elasticity distribution of biological tissue, which is often altered in pathological states. In this work, we report quantitative photoacoustic elastography (QPAE), capable of measuring Young's modulus of human tissue in vivo. By combining photoacoustic elastography with a stress sensor having known stress-strain behavior, QPAE can simultaneously measure strain and stress, from which Young's modulus is calculated. We first applied QPAE to quantify the Young's modulus of tissue-mimicking agar phantoms with different concentrations. The measured values fitted well with both the empirical expectations based on the agar concentrations and those measured in independent standard compression tests. We then demonstrated the feasibility of QPAE by measuring the Young's modulus of human skeletal muscle in vivo. The data showed a linear relationship between muscle stiffness and loading. The results proved that QPAE can noninvasively quantify the absolute elasticity of biological tissue, thus enabling longitudinal imaging of tissue elasticity. QPAE can be exploited for both preclinical biomechanics studies and clinical applications.
Device for measuring elastic modulus of superconducting coils (See 7903169)
1979-01-01
This device was made to measure elastic modulus of the Po dipole superconducting coils. More elaborated devices, but based on the same concept, were later used to measure the apparent elastic moduli of the LHC superconducting magnet coils. See also 7903169, 7901386.
Determination of bending modulus of elasticity of Pterygota ...
African Journals Online (AJOL)
Two different international testing norms, DIN52186 (1978) and ISO8375 (1985) were used to determine the bending modulus of elasticity (MOE) of Pterygota macrocarpa K. Schum (Kyere) and Piptadeniastrum africanum (Dahoma). The results from the two testing norms for each timber species were highly correlated, with ...
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
Introduction and preliminaries. In [2], Belkina and Platonov proved the equivalence theorem for a K-functional and a modulus of smoothness for the Dunkl transform in the Hilbert space L2(R, |x|2α+1. ), α > −1/2, using a Dunkl translation operator. In this paper, we prove the analog of this result (see [2]) in the Hilbert space.
Connecting Jacobi elliptic functions with different modulus parameters
Indian Academy of Sciences (India)
Abstract. The simplest formulas connecting Jacobi elliptic functions with different modulus parameters were first obtained over two hundred years ago by John Landen. His approach was to change integration variables in elliptic integrals. We show that. Landen's formulas and their subsequent generalizations can also be ...
Device to measure elastic modulus of superconducting windings
CERN PhotoLab
1979-01-01
This device was made to measure elastic modulus of the Po dipole superconducting coils. More elaborated devices, but based on the same concept, were later used to measure the apparent elastic moduli of the LHC superconducting magnet coils. See also 7903547X, 7901386.
High elastic modulus nanopowder reinforced resin composites for dental applications
Wang, Yijun
2007-12-01
Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with effective coupling agents and higher filler loading, viscous flow can be greatly decreased due to the
Investigation of the elastic modulus of SSC coils
Energy Technology Data Exchange (ETDEWEB)
Markley, F.; Kerby, J.; Sizemore, B.; Khoun, C.; King, T.
1991-03-01
The Materials Development Laboratory at Fermilab has been conducting experiments on the mechanical properties of superconducting coils. Two of these measurements were designed to measure the elastic modulus of actual SSC coils in an effort to increase the precision of previously reported data. The first experiment utilizes a fixture redesigned for increased stiffness, in an attempt to reduce uncertainty in the data. As in the previous fixture of this type, the inner coil radius has been left unconstrained. The second fixture constrains the coil on all sides, allowing for the determination of the radial and azimuthal components of the cured coil modulus. A finite element model of the first test arrangement was also created to predict the compliance of the fixture, and compare numerical predictions with the experimental data. The results from this fixture suggest that the coil modulus is higher than previously reported, at 1.43{plus minus}0.03{times}10{sup 10} Pa (2.08{plus minus}.05{times}10{sup 6} psi). The main difference between the two experiments were the compliance of the fixture, which was found to have been seriously underestimated in last years test. Results from the second fixture suggest a coil modulus of 8.48{plus minus}0.82{times}10{sup 9} Pa (1.23{plus minus}0.12{times}10{sup 6} psi) for the azimuthal modulus, and between 8.96{plus minus}0.822{times}10{sup 9} Pa (1.3{plus minus}0.12{times}10{sup 6} psi) at lower loads and 1.12{plus minus}0.24{times}10{sup 10} Pa (1.63{plus minus}0.35{times}10{sup 6} psi) at higher loads in the radial direction. For a constrained coil, little difference is noted between the radial and azimuthal moduli of the coil. 2 refs., 8 figs.
Investigation of the elastic modulus of SSC coils
Energy Technology Data Exchange (ETDEWEB)
Markley, F.; Kerby, J.; Sizemore, B.; Khoun, C.; King, T.
1991-03-01
The Materials Development Laboratory at Fermilab has been conducting experiments on the mechanical properties of superconducting coils. Two of these measurements were designed to measure the elastic modulus of actual SSC coils in an effort to increase the precision of previously reported data. The first experiment utilizes a fixture redesigned for increased stiffness, in an attempt to reduce uncertainty in the data. As in the previous fixture of this type, the inner coil radius has been left unconstrained. The second fixture constrains the coil on all sides, allowing for the determination of the radial and azimuthal components of the cured coil modulus. A finite element model of the first test arrangement was also created to predict the compliance of the fixture, and compare numerical predictions with the experimental data. The results from this fixture suggest that the coil modulus is higher than previously reported, at 1.43{plus_minus}0.03{times}10{sup 10} Pa (2.08{plus_minus}.05{times}10{sup 6} psi). The main difference between the two experiments were the compliance of the fixture, which was found to have been seriously underestimated in last years test. Results from the second fixture suggest a coil modulus of 8.48{plus_minus}0.82{times}10{sup 9} Pa (1.23{plus_minus}0.12{times}10{sup 6} psi) for the azimuthal modulus, and between 8.96{plus_minus}0.822{times}10{sup 9} Pa (1.3{plus_minus}0.12{times}10{sup 6} psi) at lower loads and 1.12{plus_minus}0.24{times}10{sup 10} Pa (1.63{plus_minus}0.35{times}10{sup 6} psi) at higher loads in the radial direction. For a constrained coil, little difference is noted between the radial and azimuthal moduli of the coil. 2 refs., 8 figs.
UV caps and modulus stabilization for 6D gauged chiral supergravity
Burgess, Cliff P.; Hoover, Doug; Tasinato, Gianmassimo
2007-09-01
We describe an explicit UV regularization of the brane singularities for all 4D flat configurations of 6D gauged chiral supergravity compactified on axially symmetric internal spaces (for which the general solutions are known). All such solutions have two or fewer co-dimension two singularities, which we resolve in terms of microscopic co-dimension one cylindrical 4-branes, whose interiors are capped using the most general possible 4D flat solution of the 6D field equations. By so doing we show that such a cap is always possible for any given bulk geometry, and obtain an explicit relationship between the properties of the capped 4-branes and the various parameters which describe the bulk solution. We show how these branes generically stabilize the size of the extra dimensions by breaking the scale invariance which relates classical solutions to 6D supergravity, and we compute the scalar potential for this modulus in the 4D effective theory. The lifting of this marginal direction provides a natural realization of the Goldberger-Wise stabilization mechanism in six dimensions.
Steve P. Verrill; Frank C. Owens; David E. Kretschmann; Rubin Shmulsky
2017-01-01
It is common practice to assume that a two-parameter Weibull probability distribution is suitable for modeling lumber properties. Verrill and co-workers demonstrated theoretically and empirically that the modulus of rupture (MOR) distribution of visually graded or machine stress rated (MSR) lumber is not distributed as a Weibull. Instead, the tails of the MOR...
Directory of Open Access Journals (Sweden)
Savatier Vincent
2016-01-01
Limit pressure and Ménard pressuremeter modulus variation with respect to drought in silty clay situated in water-table fluctuation area. Finally, we will try to show the consequences of these stress paths for performing and interpreting pressuremeter test in unsaturated and collapsible soils.
DEFF Research Database (Denmark)
Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel
2015-01-01
the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...
Creating bulk nanocrystalline metal.
Energy Technology Data Exchange (ETDEWEB)
Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin
2008-10-01
Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.
Simplified equation for Young's modulus of CNT reinforced concrete
Chandran, RameshBabu; Gifty Honeyta A, Maria
2017-12-01
This research investigation focuses on finite element modeling of carbon nanotube (CNT) reinforced concrete matrix for three grades of concrete namely M40, M60 and M120. Representative volume element (RVE) was adopted and one-eighth model depicting the CNT reinforced concrete matrix was simulated using FEA software ANSYS17.2. Adopting random orientation of CNTs, with nine fibre volume fractions from 0.1% to 0.9%, finite element modeling simulations replicated exactly the CNT reinforced concrete matrix. Upon evaluations of the model, the longitudinal and transverse Young's modulus of elasticity of the CNT reinforced concrete was arrived. The graphical plots between various fibre volume fractions and the concrete grade revealed simplified equation for estimating the young's modulus. It also exploited the fact that the concrete grade does not have significant impact in CNT reinforced concrete matrix.
Multigene Genetic Programming for Estimation of Elastic Modulus of Concrete
Directory of Open Access Journals (Sweden)
Alireza Mohammadi Bayazidi
2014-01-01
Full Text Available This paper presents a new multigene genetic programming (MGGP approach for estimation of elastic modulus of concrete. The MGGP technique models the elastic modulus behavior by integrating the capabilities of standard genetic programming and classical regression. The main aim is to derive precise relationships between the tangent elastic moduli of normal and high strength concrete and the corresponding compressive strength values. Another important contribution of this study is to develop a generalized prediction model for the elastic moduli of both normal and high strength concrete. Numerous concrete compressive strength test results are obtained from the literature to develop the models. A comprehensive comparative study is conducted to verify the performance of the models. The proposed models perform superior to the existing traditional models, as well as those derived using other powerful soft computing tools.
Young's Modulus of Single-Crystal Fullerene C Nanotubes
Directory of Open Access Journals (Sweden)
Tokushi Kizuka
2012-01-01
Full Text Available We performed bending tests on single-crystal nanotubes composed of fullerene C70 molecules by in situ transmission electron microscopy with measurements of loading forces by an optical deflection method. The nanotubes with the outer diameters of 270–470 nm were bent using simple-beam and cantilever-beam loading by the piezomanipulation of silicon nanotips. Young's modulus of the nanotubes increased from 61 GPa to 110 GPa as the outer diameter decreased from 470 nm to 270 nm. Young's modulus was estimated to be 66% of that of single-crystal C60 nanotubes of the same outer diameter.
A Methodology for Determination of Resilient Modulus of Asphaltic Concrete
Directory of Open Access Journals (Sweden)
A. Patel
2011-01-01
Full Text Available Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV, give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements, was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.
Study on the Compressive Modulus of Nylon-11/Silica Nanocomposites
Directory of Open Access Journals (Sweden)
Haseung Chung
2012-01-01
Full Text Available This paper investigates the unusual characteristics regarding the mechanical properties of Nylon-11 filled with different volume fractions of silica nanoparticles by selective laser sintering (SLS from numerical simulation. The compressive modulus was predicted by two different numerical models and compared with the experimentally measured one. While the two-phase model has a limited capability in explaining the unusual behavior shown in the compressive modulus obtained by experiments with 2% volume fraction of nanoparticles, the effective interface model can simulate the unexpected characteristic of nanocomposites according to the volume fraction of nanoparticles. We can conclude that the effective interface model should be employed to predict the mechanical properties of nanocomposites for efficiency and accuracy.
Influence of compression pressure on Young's modulus of ceramic samples
Al-Shantir, Omar; Trník, Anton
2017-07-01
The samples used in this study are created from a porcelain mixture. This mixture is a high strength aluminous porcelain which is used in electrotechnical engineering (high voltage insulators). The porcelain mixture contains clay, kaolin, feldspar, alumina, and small amount of other admixtures. The samples are made with three different compression pressures (80, 90, and 110 MPa). Impulse excitation technique, termodilatometry, and termogravimetry are used to determine Young's modulus. The analyses are performed in the temperature range from 30 °C to 1100 °C with a heating rate of 5 °C/min in a static air atmosphere. It is found out that values of Young's modulus do not increase linearly with the compression pressure.
Ultrasonic Measurement of Elastic Modulus of Kelvin Foam
Directory of Open Access Journals (Sweden)
Oh Sukwon
2016-01-01
Full Text Available Elastic modulus of 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam of 3 mm unit cell is designed and printed layer upon layer to fablicate a Kelvin foam plate of 14mm thickness by 3D CAD/printer using ABS plastic. The Kelvin foam plate is filled completely with paraffin wax for impedance matching, so that acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF method to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity.
Biaxial flexural modulus of antibiotic-impregnated orthopedic bone cement.
Leone, James; Johnson, Amy; Ziada, Samir; Hashemi, Ata; Adili, Anthony; de Beer, Justin
2007-10-01
Previously reported antibiotic-impregnated cement strengths have been based on uniaxial and fatigue testing methodologies. These methods may not provide an accurate characterization of bone cement's true load-bearing capacity in total joint replacement (TJR). The present study utilized biaxial testing to report on the properties of antibiotic-impregnated cement. Test groups included: PMMA mixed with Vancomycin, Gentamicin, Tobramycin, or no antibiotic (control). In comparison to the control group, PMMA samples mixed with powdered gentamicin resulted in an increase in the mean elastic modulus by 6.50% versus a drop noted with powdered vancomycin and tobramycin by 2.65 and 1.37% respectively. The mean elastic modulus in samples containing liquid gentamicin dropped by 11.6%. This study supports the continued use of powdered antibiotics when clinically indicated, but suggest caution in the use of liquid gentamicin in TJR.
Young's modulus of elasticity of Schlemm's canal endothelial cells.
Zeng, Dehong; Juzkiw, Taras; Read, A Thomas; Chan, Darren W-H; Glucksberg, Matthew R; Ethier, C Ross; Johnson, Mark
2010-02-01
Schlemm's canal (SC) endothelial cells are likely important in the physiology and pathophysiology of the aqueous drainage system of the eye, particularly in glaucoma. The mechanical stiffness of these cells determines, in part, the extent to which they can support a pressure gradient and thus can be used to place limits on the flow resistance that this layer can generate in the eye. However, little is known about the biomechanical properties of SC endothelial cells. Our goal in this study was to estimate the effective Young's modulus of elasticity of normal SC cells. To do so, we combined magnetic pulling cytometry of isolated cultured human SC cells with finite element modeling of the mechanical response of the cell to traction forces applied by adherent beads. Preliminary work showed that the immersion angles of beads attached to the SC cells had a major influence on bead response; therefore, we also measured bead immersion angle by confocal microscopy, using an empirical technique to correct for axial distortion of the confocal images. Our results showed that the upper bound for the effective Young's modulus of elasticity of the cultured SC cells examined in this study, in central, non-nuclear regions, ranged between 1,007 and 3,053 Pa, which is similar to, although somewhat larger than values that have been measured for other endothelial cell types. We compared these values to estimates of the modulus of primate SC cells in vivo, based on images of these cells under pressure loading, and found good agreement at low intraocular pressure (8-15 mm Hg). However, increasing intraocular pressure (22-30 mm Hg) appeared to cause a significant increase in the modulus of these cells. These moduli can be used to estimate the extent to which SC cells deform in response to the pressure drop across the inner wall endothelium and thereby estimate the extent to which they can generate outflow resistance.
Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel
Allison, P. G.; Horstemeyer, M. F.; Brown, H. R.
2012-07-01
This article compares the existing theoretical expressions for the porosity dependence on elastic constants to experimental data for a commercially available material, FC-0205 powder metallurgy (PM) steel. The modulus of compression, tension, effective torsion, and ultrasound-based data at varying porosity levels are plotted graphically against the theoretical expressions. An equation by McAdam ( J. Iron Steel Inst. Lond., 1950, 168, p 346) was able to most accurately predict the experimental data with the adjustment of only one material constant.
Measurement of the elasticity modulus of soft tissues.
Zörner, S; Kaltenbacher, M; Lerch, R; Sutor, A; Döllinger, M
2010-05-28
A measurement setup combined with a Finite Element (FE) simulation is presented to determine the elasticity modulus of soft materials as a function of frequency. The longterm goal of this work is to measure in vitro the elasticity modulus of human vocal folds over a frequency range that coincides with the range of human phonation. The results will assist numerical simulations modeling the phonation process by providing correct material parameters. Furthermore, the measurements are locally applied, enabling to determine spatial differences along the surface of the material. In this work the method will be presented and validated by applying it to silicones with similar characteristics as human vocal folds. Three silicone samples with different consistency were tested over a frequency range of 20-250 Hz. The results of the pipette aspiration method revealed a strong frequency dependency of the elasticity modulus, especially below 100 Hz. In this frequency range the elasticity moduli of the samples varied between 5 and 27 kPa. Copyright 2010 Elsevier Ltd. All rights reserved.
Determination of the flexural modulus of elasticity of orthodontic archwires.
Tian, Kun; Darvell, Brian W
2010-08-01
To design a protocol for the determination of the flexural modulus of elasticity of wire with high accuracy and precision. Cantilever bending was used at long span and low loads, using a laser displacement sensor. Various wires were tested for proof-of-concept: stainless steel, Elgiloy, Wiptam and a gold alloy, with primary attention being paid to the source and magnitude of errors. The moduli of elasticity were determined with a median relative error of approximately 0.15%, with a worst case of 0.56%, taking into account all measurement errors. The precision was such as to permit distinctions between the values for the wires of different thermomechanical history. The determination of the elastic modulus of wires may be made with good precision using cantilever bending providing attention is given to all sources of error. These results represent the most reliable measures of modulus of elasticity of orthodontic archwires to date. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Elastohydrodynamics of elliptical contacts for materials of low elastic modulus
Hamrock, B. J.; Dowson, D.
1983-01-01
The influence of the ellipticity parameter k and the dimensionless speed U, load W, and materials G parameters on minimum film thickness for materials of low elastic modulus was investigated. The ellipticity parameter was varied from 1 (a ball-on-plane configuration) to 12 (a configuration approaching a line contact); U and W were each varied by one order of magnitude. Seventeen cases were used to generate the minimum- and central-film-thickness relations. The influence of lubricant starvation on minimum film thickness in starved elliptical, elastohydrodynamic configurations was also investigated for materials of low elastic modulus. Lubricant starvation was studied simply by moving the inlet boundary closer to the center of the conjunction in the numerical solutions. Contour plots of pressure and film thickness in and around the contact were presented for both fully flooded and starved lubrication conditions. It is evident from these figures that the inlet pressure contours become less circular and closer to the edge of the Hertzian contact zone and that the film thickness decreases substantially as the serverity of starvation increases. The results presented reveal the essential features of both fully flooded and starved, elliptical, elastohydrodynamic conjunctions for materials of low elastic modulus.
Elastic modulus of tree frog adhesive toe pads.
Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N
2011-10-01
Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.
Pengukuran Modulus Elastisitas Dinamis Batuan dengan Metode Seismik Refraksi
Directory of Open Access Journals (Sweden)
Ashadi Salim
2012-12-01
Full Text Available The seismic wave velocity in rock formation depends on the elastic modulus and mass density of rock where the wave travels. The velocity measurement of P and S waves on rock formation and the mass density in the laboratory can be used for calculating the elastic modulus of rock formation. The elastic modulus is part of rock mechanical parameter needed in geological engineering researches. The velocity measurement of P and S waves by the seismic refraction method was done on a tunnel with 11 spreads of measurement. From the resultsof the measurement, three groups of rock formation could be identified. The first is rock formation with Ed=8.890-12.68 MPa and G=3.306-4.830MPa; the second group is rock formation with Ed=8.890-12.68 MPa and G=3.306-4.830MPa; and the third group is with Ed=18.520-21.120MPa and G=6.724-7.744MP. The first group is clay formation while the second and third groups are andesitic stone formation.
Compressive elastic modulus of natural fiber based binary composites
Widayani, Susanah, Y.; Utami, L. S.; Khotimah, S. N.; Viridi, S.
2012-06-01
The composites made of bamboo apus fiber - epoxy resin and charcoal - tapioca starch with several compositions have been synthesized. Bamboo fiber powder as the rest of cutting process was refined and filtered by mesh 40 before used. Epoxy resin 1021A and hardener 1021B has been used as resin. The synthesis of epoxy resin-based composites was carried out via simple mixing method by adding adequate 70% ethanol solution before drying. The 100 mesh-filtered dry charcoal was mixed with tapioca mixture before it was pressed and dried to produce briquette composites. To study the compressive elastic modulus of the composites, pressure tests using Mark 10 Pressure Test Machine have been carried out. It was found that all the composites show maximum compressive elastic modulus at certain component compositions. The maximum elastic modulus for bamboo fiber-epoxy resin, charcoal - epoxy resin and charcoal-tapioca starch were observed at 52.9%, 56.3%, and 25.0% of mass fraction of bamboo fiber, charcoal and tapioca starch, respectively.
Measuring the elastic modulus of ex vivo small tissue samples.
Samani, Abbas; Bishop, Jonathan; Luginbuhl, Chris; Plewes, Donald B
2003-07-21
Over the past decade, several methods have been proposed to image tissue elasticity based on imaging methods collectively called elastography. While progress in developing these systems has been rapid, the basic understanding of tissue properties to interpret elastography images is generally lacking. To address this limitation, we developed a system to measure the Young's modulus of small soft tissue specimens. This system was designed to accommodate biological soft tissue constraints such as sample size, geometry imperfection and heterogeneity. The measurement technique consists of indenting an unconfined small block of tissue while measuring the resulting force. We show that the measured force-displacement slope of such a geometry can be transformed to the tissue Young's modulus via a conversion factor related to the sample's geometry and boundary conditions using finite element analysis. We also demonstrate another measurement technique for tissue elasticity based on quasi-static magnetic resonance elastography in which a tissue specimen encased in a gelatine-agarose block undergoes cyclical compression with resulting displacements measured using a phase contrast MRI technique. The tissue Young's modulus is then reconstructed from the measured displacements using an inversion technique. Finally, preliminary elasticity measurement results of various breast tissues are presented and discussed.
KOVALEV OLEG; KUZKIN VITALY
2011-01-01
In the present paper simple analytical expressions connecting bulk moduli for fullerenes C20 and C60 with stiffness of interatomic bond and geometrical characteristics of the fullerenes are derived. Ambiguities related to definition of the bulk modulus are discussed. Nonlinear volumetrical deformation of the fullerenes is considered. Pressure-volume dependence for the fullerenes under volumetrical compression are derived. Simple analytical model for volumetrical vibrations of the fullerenes i...
Interaction of bone-dental implant with new ultra low modulus alloy using a numerical approach.
Piotrowski, B; Baptista, A A; Patoor, E; Bravetti, P; Eberhardt, A; Laheurte, P
2014-05-01
Although mechanical stress is known as being a significant factor in bone remodeling, most implants are still made using materials that have a higher elastic stiffness than that of bones. Load transfer between the implant and the surrounding bones is much detrimental, and osteoporosis is often a consequence of such mechanical mismatch. The concept of mechanical biocompatibility has now been considered for more than a decade. However, it is limited by the choice of materials, mainly Ti-based alloys whose elastic properties are still too far from cortical bone. We have suggested using a bulk material in relation with the development of a new beta titanium-based alloy. Titanium is a much suitable biocompatible metal, and beta-titanium alloys such as metastable TiNb exhibit a very low apparent elastic modulus related to the presence of an orthorhombic martensite. The purpose of the present work has been to investigate the interaction that occurs between the dental implants and the cortical bone. 3D finite element models have been adopted to analyze the behavior of the bone-implant system depending on the elastic properties of the implant, different types of implant geometry, friction force, and loading condition. The geometry of the bone has been adopted from a mandibular incisor and the surrounding bone. Occlusal static forces have been applied to the implants, and their effects on the bone-metal implant interface region have been assessed and compared with a cortical bone/bone implant configuration. This work has shown that the low modulus implant induces a stress distribution closer to the actual physiological phenomenon, together with a better stress jump along the bone implant interface, regardless of the implant design. Copyright © 2014 Elsevier B.V. All rights reserved.
Microfabricated Bulk Piezoelectric Transformers
Barham, Oliver M.
Piezoelectric voltage transformers (PTs) can be used to transform an input voltage into a different, required output voltage needed in electronic and electro- mechanical systems, among other varied uses. On the macro scale, they have been commercialized in electronics powering consumer laptop liquid crystal displays, and compete with an older, more prevalent technology, inductive electromagnetic volt- age transformers (EMTs). The present work investigates PTs on smaller size scales that are currently in the academic research sphere, with an eye towards applications including micro-robotics and other small-scale electronic and electromechanical sys- tems. PTs and EMTs are compared on the basis of power and energy density, with PTs trending towards higher values of power and energy density, comparatively, indicating their suitability for small-scale systems. Among PT topologies, bulk disc-type PTs, operating in their fundamental radial extension mode, and free-free beam PTs, operating in their fundamental length extensional mode, are good can- didates for microfabrication and are considered here. Analytical modeling based on the Extended Hamilton Method is used to predict device performance and integrate mechanical tethering as a boundary condition. This model differs from previous PT models in that the electric enthalpy is used to derive constituent equations of motion with Hamilton's Method, and therefore this approach is also more generally applica- ble to other piezoelectric systems outside of the present work. Prototype devices are microfabricated using a two mask process consisting of traditional photolithography combined with micropowder blasting, and are tested with various output electri- cal loads. 4mm diameter tethered disc PTs on the order of .002cm. 3 , two orders smaller than the bulk PT literature, had the followingperformance: a prototype with electrode area ratio (input area / output area) = 1 had peak gain of 2.3 (+/- 0.1), efficiency of 33 (+/- 0
Developing bulk exchange spring magnets
Energy Technology Data Exchange (ETDEWEB)
Mccall, Scott K.; Kuntz, Joshua D.
2017-06-27
A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.
3D Modeling Effect of Spherical Inclusions on the Magnetostriction of Bulk Superconductors
Zhao, Yufeng; Pan, Baocai
2018-02-01
In this paper, the dependence of the effective magnetostriction of bulk superconductors on the elastic parameters including the volume fraction and elastic modulus ratio is studied by a three-dimensional model consisting of a spherical inclusion-superconducting matrix system. The effect of the elastic modulus and volume fraction on the magnetostriction is also obtained through the magnetostriction loop. The results indicate that the elastic modulus and volume fraction have obvious effects on the effective magnetostriction of the superconducting composite, which gives an explanation about the differences between the experimental and the theoretical results. Furthermore, it is worth pointing out that the linear field dependence of magnetostriction is unique to the Bean model by comparing the curve shapes of the magnetostriction loop with and without inclusion.
Determination of resilient modulus values for typical plastic soils in Wisconsin.
2011-09-01
"The objectives of this research are to establish a resilient modulus test results database and to develop : correlations for estimating the resilient modulus of Wisconsin fine-grained soils from basic soil properties. A : laboratory testing program ...
Evaluation of Variability in Resilient Modulus Test Results (ASTM D4123)
1989-10-01
Samples of asphalt mixture were evaluated in the laboratory under various conditions to evaluate the repeatability of the resilient modulus test and to evaluate the effect of stress on the measured resilient modulus. Some of the samples were prepared...
Correlating off-axis tension tests to shear modulus of wood-based panels
Edmond P. Saliklis; Robert H. Falk
2000-01-01
The weakness of existing relationships correlating off-axis modulus of elasticity E q to shear modulus G 12 for wood composite panels is demonstrated through presentation of extensive experimental data. A new relationship is proposed that performs better than existing equations found in the literature. This relationship can be manipulated to calculate the shear modulus...
Resin composites: Modulus of elasticity and marginal quality.
Benetti, Ana R; Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon
2014-09-01
To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity but quite similar polymerization contraction. MOD cavities (n=30) were prepared in extracted premolars, restored and then subjected to thermocyclic and mechanical loading. Marginal quality of the restorations before and after loading was analyzed on epoxy replicas under a scanning electron microscope. The percentage of gap-free margins and occurrence of paramarginal fractures were registered. Modulus of elasticity and polymerization contraction were analyzed with parametric and margins with nonparametric ANOVA and post hoc Tukey HSD or Wilcoxon rank-sum tests, respectively. The number of paramarginal fractures was analyzed with exact Fisher tests (α=0.05). Grandio demonstrated significantly more gap-free enamel margins than Charisma and Filtek Supreme XTE, before and after loading (p0.05). No significant effect of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (pmodulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. The results from this study suggest that the marginal quality of restorations can be improved by the selection of a resin composite with modulus of elasticity close to that of dentine, although an increase in paramarginal enamel fractures can result as a consequence. Copyright © 2014 Elsevier Ltd. All rights reserved.
Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials
Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)
2015-01-01
A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.
Supernovae Light Curves: An Argument for a New Distance Modulus
Jensen, Jerry W.
2004-01-01
Supernovae Ia (SNe Ia) light curves have been used to prove the universe is expanding. As standard candles, SNe Ia appear to indicate the rate of expansion has increased in the past and is now decreasing. This independent evaluation of SNe Ia light curves demonstrates a Malmquist Type II bias exists in the body of supernova data. If this bias is properly addressed, there is very little budget for time dilation in the light curves of supernova. A non-relativistic distance modulus is proposed, ...
Bacon, J. F.
1971-01-01
Emphasis on the consideration of glass formation on a kinetic process made it possible to think of glass compositions different from those normally employed in the manufacture of glass fibers. Approximately 450 new glass compositions were prepared and three dozen of these compositions have values for Young's modulus measured on bulk specimens greater than nineteen million pounds per square inch. Of the new glasses about a hundred could be drawn into fibers by mechanical methods at high speeds. The fiber which has a Young's modulus measured on the fiber of 18.6 million pounds per square inch and has been prepared in quantity as a monofilament (to date more than 150 million lineal feet of 0.2 to 0.4 mil fiber have been produced). This fiber has also been successfully incorporated both in epoxy and polyimide matrices. The epoxy resin composite has shown a modulus forty percent better than that achievable using the most common grade of competitive glass fiber, and twenty percent better than that obtainable with the best available grade of competitive glass fiber. Other glass fibers of even higher modulus have been developed.
Directory of Open Access Journals (Sweden)
Feng Xue
2015-04-01
Full Text Available In this paper, the flux-pinning-induced elastic stress analysis considering the crack-inclusion interaction is carried out for a bulk superconductor in the magnetization process. A approximate model for the crack problem of a bulk superconductor with nonsuperconducting inclusions (particles dispersed in a superconducting matrix is described. The crack is simulated as a continuous distribution of edge dislocations in the solution procedure. The obtained results show that, the shear modulus, inclusion-crack size, inclusion-crack distance, and also the magnetic field have obvious effects on the stress intensity factors (SIFs at the crack tips of the superconductor.
Complex modulus estimation respecting causality: Application to viscoelastic bars
Collet, P.; Gary, G.; Lundberg, B.; Mohr, D.
2012-08-01
The identification of linear visco-elasticity models mostly focuses on the real and imaginary parts of the Young's modulus. Many methods have been proposed in the past to identify these material model parameters from experiments. However, when these parameters are determined independently, they are likely to violate the principle of causality. The present work presents a method that accounts for the constraints of causality and positivity of dissipation rate. The proposed method is based on a finite set of n measured angular frequencies and complex moduli. It includes a noise reduction procedure and provides a rheological 2p + 1)-parameter model with p modulus on the positive imaginary frequency axis are determined by p parameters which are obtained as the common positive zeros of a special class of rational functions, while the remaining parameters are obtained from a least squares fit. The level of refinement of the rheological model, expressed by p, is not an assumed value but a result of the method. The method is applied to an impact test with a Nylon bar specimen. In this case, data at the n = 29 lowest resonance frequencies resulted in a rheological model with 14 parameters (p = 6). The validity of the method is checked through supplementary experimental results at low frequencies.
Non-classical Response and Shear Modulus of Solid 4He
Kim, D. Y.; Kwon, S.; Choi, H.; Choi, W. S.; Kim, E.; Kim, H. C.
2010-03-01
The relation between the nonclassical rotational inertia (NCRI) and the shear modulus increase of solid 4He was investigated. A pair of piezoelectric transducers is positioned in the center of a torsional oscillator to measure the shear modulus. We observe the NCRI and the shear modulus increases below 200mK with similar temperature, measurement drive, and frequency dependence. The drive and frequency dependence in the shear modulus increase can be understood by the model of thermally assisted unpinning of dislocations from impurities. However, the shear modulus increase is found to be insufficient to explain the magnitude of the NCRI. In addition, no linear correlation between the magnitude of the NCRI and the shear modulus increase is found and the magnitude of shear modulus shows a rather negative correlation with that of NCRI.
Radiation effects in bulk silicon
Claeys, Cor; Vanhellemont, Jan
1994-01-01
This paper highlights important aspects related to irradiation effects in bulk silicon. Some basic principles related to the interaction of radiation with material, i.e. ionization and atomic displacement, are briefly reviewed. A physical understanding of radiation effects strongly depends on the availability of appropriate analytical tools. These tools are critically accessed from a silicon bulk viewpoint. More detailed information, related to the properties of the bulk damage and some dedicated application aspects, is given for both electron and proton irradiations. Emphasis is placed on radiation environments encountered during space missions and on their influence on the electrical performance of devices such as memories and image sensors.
Tiryaki, Sebahattin; Aras, Uğur; Kalaycıoğlu, Hülya; Erişir, Emir; Aydın, Aytaç
2017-07-01
Determining the mechanical properties of particleboard has gained a great importance due to its increasing usage as a building material in recent years. This study aims to develop artificial neural network (ANN) and multiple linear regression (MLR) models for predicting modulus of rupture (MOR) and modulus of elasticity (MOE) of particleboard depending on different pressing temperature, pressing time, pressing pressure and resin type. Experimental results indicated that the increased pressing temperature, time and pressure in manufacturing process generally improved the mechanical properties of particleboard. It was also seen that ANN and MLR models were highly successful in predicting the MOR and MOE of particleboard under given conditions. On the other hand, a comparison between ANN and MLR revealed that the ANN was superior compared to the MLR in predicting the MOR and MOE. Finally, the findings of this study are expected to provide beneficial insights for practitioners to better understand usability of such composite materials for engineering applications and to better assess the effects of pressing conditions on the MOR and MOE of particleboard.
In vivo performance of a reduced-modulus bone cement
Forehand, Brett Ramsey
Total joint replacement has become one of the most common procedures in the area of orthopedics and is often the solution in patients with diseased or injured hip joints. Component loosening is a significant problem and is primarily caused by bone resorption at the bone-cement interface in cemented implants. It is our hypothesis that localized shear stresses are responsible for the resorption. It was previously shown analytically that local stresses at the interface could be reduced by using a cement of lower modulus. A new reduced modulus cement, polybutyl methylmethacrylate (PBMMA), was developed to test the hypothesis. PBMMA was formulated to exist as polybutyl methacrylate filler in a polymethyl methacrylate matrix. The success of PBMMA cement is based largely on the fact that the polybutyl component of the cement will be in the rubbery state at body temperature. In vitro characterization of the cement was undertaken previously and demonstrated a modulus of approximately one-eighth that of conventional bone cement, polymethyl methacrylate (PMMA) and increased fracture toughness. The purpose of this experiment was to perform an in vivo comparison of the two cements. A sheep model was selected. Total hip arthroplasty was performed on 50 ewes using either PBMMA or PMMA. Radiographs were taken at 6 month intervals. At one year, the contralateral femur of each sheep was implanted so that each animal served as its own control, and the animals were sacrificed. The stiffness of the bone-cement interface of the femoral component within the femur was assessed by applying a torque to the femoral component and demonstrated a significant difference in loosening between the cements when the specimens were tested in external rotation (p < 0.007). Evaluation of the mechanical data also suggests that the PBMMA sheep had a greater amount of loosening for each subject, 59% versus 4% for standard PMMA. A radiographic analysis demonstrated more signs of loosening in the PMMA series
Silicon Bulk Micromachined Vibratory Gyroscope
Tang, T. K.; Gutierrez, R. C.; Wilcox, J. Z.; Stell, C.; Vorperian, V.; Calvet, R.; Li, W. J.; Charkaborty, I.; Bartman, R.; Kaiser, W. J.
1996-01-01
This paper reports on design, modeling, fabrication, and characterization of a novel silicon bulk micromachined vibratory rate gyroscope designed for microspacecraft applications. The new microgyroscope consists of a silicon four leaf cloverstructure with a post attached to the center.
Separation of attractors in 1-modulus quantum corrected special geometry
Bellucci, S; Marrani, A; Shcherbakov, A
2008-01-01
We study the solutions to the N=2, d=4 Attractor Equations in a dyonic, extremal, static, spherically symmetric and asymptotically flat black hole background, in the simplest case of perturbative quantum corrected cubic Special Kahler geometry consistent with continuous axion-shift symmetry, namely in the 1-modulus Special Kahler geometry described (in a suitable special symplectic coordinate) by the holomorphic Kahler gauge-invariant prepotential F=t^3+i*lambda, with lambda real. By performing computations in the ``magnetic'' charge configuration, we find evidence for interesting phenomena (absent in the classical limit of vanishing lambda). Namely, for a certain range of the quantum parameter lambda we find a ``splitting'' of attractors, i.e. the existence of multiple solutions to the Attractor Equations for fixed supporting charge configuration. This corresponds to the existence of ``area codes'' in the radial evolution of the scalar t, determined by the various disconnected regions of the moduli space, wh...
DEM interpolation weight calculation modulus based on maximum entropy
Chen, Tian-wei; Yang, Xia
2015-12-01
There is negative-weight in traditional interpolation of gridding DEM, in the article, the principle of Maximum Entropy is utilized to analyze the model system which depends on modulus of space weight. Negative-weight problem of the DEM interpolation is researched via building Maximum Entropy model, and adding nonnegative, first and second order's Moment constraints, the negative-weight problem is solved. The correctness and accuracy of the method was validated with genetic algorithm in matlab program. The method is compared with the method of Yang Chizhong interpolation and quadratic program. Comparison shows that the volume and scaling of Maximum Entropy's weight is fit to relations of space and the accuracy is superior to the latter two.
Energy Technology Data Exchange (ETDEWEB)
1989-01-01
Papers were presented on bulk commodity demand; steel industry bulk trades; grains and the world food economy; steam coal and cement demand; shipping profitability; bulk carrier design and economics; bulk ports and terminals; ship unloading; computers in bulk terminals; and conveyors and stockyard equipment.
Directory of Open Access Journals (Sweden)
Peida Hao
2014-01-01
Full Text Available In situ nanoindentation was employed to probe the mechanical properties of individual polycrystalline titania (TiO2 microspheres. The force-displacement curves captured by a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM system were analyzed based on Hertz’s theory of contact mechanics. However, the deformation mechanisms of the nano/microspheres in the nanoindentation tests are not very clear. Finite element simulation was employed to investigate the deformation of spheres at the nanoscale under the pressure of an AFM tip. Then a revised method for the calculation of Young’s modulus of the microspheres was presented based on the deformation mechanisms of the spheres and Hertz’s theory. Meanwhile, a new force-displacement curve was reproduced by finite element simulation with the new calculation, and it was compared with the curve obtained by the nanoindentation experiment. The results of the comparison show that utilization of this revised model produces more accurate results. The calculated results showed that Young’s modulus of a polycrystalline TiO2 microsphere was approximately 30% larger than that of the bulk counterpart.
Combatting bulking sludge with ultrasound
Energy Technology Data Exchange (ETDEWEB)
Wuensch, B.; Heine, W.; Neis, U. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Dept. of Sanitary and Environmental Engineering
2002-07-01
Bulking and floating sludge cause great problems in many waste water treatment plants with biological nutrient removal. The purification as well as the sludge digestion process can be affected. These problems are due to the interlaced structure of filamentous microorganisms, which have an impact on the sludge's settling behaviour. Foam is able to build up a stable layer, which does not settle in the secondary clarifier. Foam in digestion causes a reduction of the degree of stabilisation and of the biogas production. We use low-frequency ultrasound to combat filamentous organisms in bulking sludge. Low-frequency ultrasound is suitable to create high local shear stresses, which are capable of breaking the filamentous structures of the sludge. After preliminary lab-scale tests now a full-scale new ultrasound equipment is operating at Reinfeld sewage treatment plant, Germany. The objective of this study is to explore the best ultrasound configuration to destroy the filamentous structure of bulking and foaming sludge in a substainable way. Later this study will also look into the effects of ultrasound treated bulking sludge on the anaerobic digestion process. Up to now results show that the settling behaviour of bulking sludge is improved. The minimal ultrasound energy input for destruction of bulking structure was determined. (orig.)
Modelling of bulk superconductor magnetization
Ainslie, M. D.; Fujishiro, H.
2015-05-01
This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.
Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation
Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.
2002-01-01
The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.
Bulk Mechanical Properties Testing of Metallic Marginal Glass Formers
Directory of Open Access Journals (Sweden)
Thien Q. Phan
2016-01-01
Full Text Available We developed a unique three-point bend testing apparatus to measure bulk mechanical properties of a model metallic glass alloy (SAM2X5 with nominal composition Fe49.7Cr17.1Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 prepared by spark plasma sintering. The relatively large sample sizes in the present work allowed for the preparation of test specimens with a macroscale cross section (in the millimeter range with well-controlled sample dimensions closer to standardized tests. Wire saw cutting allowed for a relatively sharp notch radius (3x smaller than previous studies and minimal sample damage. We determined that Young’s modulus and notch fracture toughness measured by our three-point bending apparatus are 230 GPa and 4.9 MPa·m1/2. Also, Vickers indentation and flexure testing provided consistent results for Young’s modulus. Indentation fracture toughness measured by Vickers indentation produced values at least 50% lower than by flexure. The microscale mechanical properties testing technique presented in this work and subsequent analyses are applicable to specimens of other compositions or ones prepared by other methods.
Effect of Cyclic Loading on Modulus of Elasticity of Aspen Wood
Milan Gaff; Miroslav Gašparík
2014-01-01
This article investigates the modulus of elasticity of solid and laminated aspen wood of various thicknesses after cyclic loading. A three-point static bending test was carried out to determine the modulus of elasticity. Cyclically loaded samples were compared with samples without cyclic loading. For the laminated wood, the results demonstrated a statistically significant impact of cyclic loading on the elasticity modulus. In contrast, no significant impact of cyclic loading was shown for the...
National Research Council Canada - National Science Library
Adachi, Hiromasa; Hasegawa, Teruo
2005-01-01
For evaluation of thermal endurance in foamed plastics, temperature and time dependence of compression dynamic modulus of four flexible polyurethane foams was investigated by dynamic viscoelastic measurements...
Jiang, Jingfeng; Brace, Chris; Andreano, Anita; DeWall, Ryan J.; Rubert, Nick; Fisher, Ted G.; Varghese, Tomy; Lee, Fred; Hall, Timothy J.
2010-01-01
The feasibility of using ultrasound-based elastic modulus imaging to visualize thermal ablation zones in an in vivo porcine model is reported in this article. Elastic modulus images of soft tissues are estimated as an inverse optimization problem. Ultrasonically-measured displacement data are utilized as inputs to determine an elastic modulus distribution that provides the best match to this displacement field. A total of 14 in vivo thermal ablation zones were investigated in this study. To determine the accuracy of delineation of each thermal ablation zone using elastic modulus imaging, the dimensions (lengths of long and short axes) and the are of each thermal ablation zone obtained from an elastic modulus image was compared to the corresponding gross pathology photograph of the same ablation zone. Comparison of elastic modulus imaging measurements and gross pathology measurements showed high correlation with respect to the area of thermal ablation zones (Pearson coefficient = 0.950 and pelastic modulus imaging can more accurately depict thermal ablation zones, when compared to strain imaging (14.7% versus 22.3% absolute percent error in area measurements, respectively). Furthermore, elastic modulus imaging also provide higher (more than a factor of two) contrast-to-noise ratios for evaluating these thermal ablation zones than those on corresponding strain images, thereby reducing inter-observer variability. Our preliminary results suggest that elastic modulus imaging might potentially enhance the ability to visualize thermal ablation zones, thereby improving assessment of ablative therapies. PMID:20354279
Directory of Open Access Journals (Sweden)
V. I. Djigan
2007-12-01
Full Text Available This paper considers the application of the linear constraints and RLS inverse QR decomposition in adaptive arrays based on constant modulus criterion. The computational procedures of adaptive algorithms are presented. Linearly constrained least squares adaptive arrays, constant modulus adaptive arrays and linearly constrained constant modulus adaptive arrays are compared via simulation. It is demonstrated, that a constant phase shift in the array output signal, caused by desired signal orientation and array weights, is compensated in a simple way in linearly constrained constant modulus adaptive arrays.
Mark Alexander Butler; Joseph Dahlen; Thomas L. Eberhardt; Cristian Montes; Finto Antony; Richard F. Daniels
2017-01-01
Key message Loblolly pine (Pinus taeda) logs can be evaluated using acoustic velocity whereby threshold acoustic velocity values can be set to ensure lumber meets specified mechanical property design values for modulus of elasticity.Â Context...
Antony Finto; Lewis Jordan; Laurence R. Schimleck; Alexander Clark; Ray A. Souter; Richard F. Daniels
2011-01-01
Modulus of elasticity (MOE), modulus of rupture (MOR), and specific gravity (SG) are important properties for determining the end-use and value of a piece of lumber. This study addressed the variation in MOE, MOR, and SG with physiographic region, tree height, and wood type. Properties were measured from two static bending samples (dimensions 25.4 mm Ã 25.4 mm Ã 406.4...
Short Exon Detection via Wavelet Transform Modulus Maxima.
Zhang, Xiaolei; Shen, Zhiwei; Zhang, Guishan; Shen, Yuanyu; Chen, Miaomiao; Zhao, Jiaxiang; Wu, Renhua
2016-01-01
The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons) in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics.
Short Exon Detection via Wavelet Transform Modulus Maxima.
Directory of Open Access Journals (Sweden)
Xiaolei Zhang
Full Text Available The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics.
Polymerization Shrinkage and Flexural Modulus of Flowable Dental Composites
Directory of Open Access Journals (Sweden)
Janaína Cavalcanti Xavier
2010-09-01
Full Text Available Linear polymerization shrinkage (LPS, flexural strength (FS and modulus of elasticity (ME of low-viscosity resin composites (Admira Flow™, Grandio Flow™/VOCO; Filtek Z350 Flow™/3M ESPE; Tetric Flow™/Ivoclar-Vivadent was evaluated using a well-established conventional micro-hybrid composite as a standard (Filtek Z250™/3M ESPE. For the measurement of LPS, composites were applied to a cylindrical metallic mould and polymerized (n = 8. The gap formed at the resin/mould interface was observed using SEM (1500×. For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10. Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. The conventional resin presented significantly lower LPS associated with high FS and ME, but only the ME values of the conventional resin differed significantly from the low-viscosity composites. The relationship between ME and LPS of low-viscosity resin composites when used as restorative material is a critical factor in contraction stress relief and marginal leakage.
Expression, crosslinking, and developing modulus master curves of recombinant resilin.
Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A
2017-05-01
Resilin is a disordered elastomeric protein found in specialized regions of insect cuticles, where low stiffness and high resilience are required. Having a wide range of functions that vary among insect species, resilin operates across a wide frequency range, from 5Hz for locomotion to 13kHz for sound production. We synthesize and crosslink a recombinant resilin from clone-1 (exon-1+exon-2) of the gene, and determine the water content (approximately 80wt%) and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. Dynamic moduli master curves have been developed, by applying the time-temperature superposition principle (TTSP) and time-temperature concentration superposition principle (TTCSP), and compared with reported master curves for natural resilin from locusts, dragonflies, and cockroaches. To our knowledge, this is the first time dynamic moduli master curves have been developed to explore the dynamic mechanical properties of recombinant resilin and compare with resilin behavior. The resulting master curves show that the synthetic resilin undergoes a pronounced transition with increasing ethanol concentrations, with the storage modulus increasing by approximately three orders of magnitude. Although possibly a glass transition, alternate explanations include the formation of intramolecular hydrogen bonds or that the chitin binding domain (ChBD) in exon-2 might change the secondary structure of the normally disordered exon-1 into more ordered conformations that limit deformation. Copyright © 2017 Elsevier Ltd. All rights reserved.
Elasticity Modulus and Flexural Strength Assessment of Foam Concrete Layer of Poroflow
Hajek, Matej; Decky, Martin; Drusa, Marian; Orininová, Lucia; Scherfel, Walter
2016-10-01
Nowadays, it is necessary to develop new building materials, which are in accordance to the principles of the following provisions of the Roads Act: The design of road is a subject that follows national technical standards, technical regulations and objectively established results of research and development for road infrastructure. Foam concrete, as a type of lightweight concrete, offers advantages such as low bulk density, thermal insulation and disadvantages that will be reduced by future development. The contribution focuses on identifying the major material characteristics of foam concrete named Poroflow 17-5, in order to replace cement-bound granular mixtures. The experimental measurements performed on test specimens were the subject of diploma thesis in 2015 and continuously of the dissertation thesis and grant research project. At the beginning of the contribution, an overview of the current use of foam concrete abroad is elaborated. Moreover, it aims to determine the flexural strength of test specimens Poroflow 17-5 in combination with various basis weights of the underlying geotextile. Another part of the article is devoted to back-calculation of indicative design modulus of Poroflow based layers based on the results of static plate load tests provided at in situ experimental stand of Faculty of Civil Engineering, University of Žilina (FCE Uniza). Testing stand has been created in order to solve problems related to research of road and railway structures. Concern to building construction presents a physical homomorphic model that is identical with the corresponding theory in all structural features. Based on the achieved material characteristics, the tensile strength in bending of previously used road construction materials was compared with innovative alternative of foam concrete and the suitability for the base layers of pavement roads was determined.
Longitudinal bulk acoustic mass sensor
DEFF Research Database (Denmark)
Hales, Jan Harry; Teva, Jordi; Boisen, Anja
2009-01-01
A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10(-15) g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise...
Energy Technology Data Exchange (ETDEWEB)
Aguila, F. del [Departamento de Fisica Teorica y del Cosmos and Centro Andaluz de Fisica de Particulas Elementales (CAFPE), Universidad de Granada, E-18071 Granada (Spain); Perez-Victoria, M. [Dipartimento di Fisica ' ' G. Galilei' ' , Universita di Padova and INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padua (Italy); Santiago, J. [Institute for Particle Physics Phenomenology, University of Durham, South Road, Durham DH1 3LE (United Kingdom)
2004-07-01
In theories with branes, bulk fields get in general divergent corrections localized on these defects. Hence, the corresponding brane terms are renormalized and should be included in the effective theory from the very beginning. We review the phenomenology associated to brane kinetic terms for different spins and backgrounds, and point out that renormalization is required already at the classical level. (orig.)
Viscoelastic properties, creep behavior and degree of conversion of bulk fill composite resins.
Papadogiannis, D; Tolidis, K; Gerasimou, P; Lakes, R; Papadogiannis, Y
2015-12-01
The aim of this study was to investigate the viscoelastic properties and creep behavior of bulk fill composites under different conditions and evaluate their degree of conversion. Seven bulk fill composites were examined: everX Posterior (EV), SDR (SD), SonicFill (SF), Tetric EvoCeram Bulk Fill (TE), Venus Bulk Fill (VE), x-tra base (XB) and x-tra fil (XF). Each material was tested at 21°C, 37°C and 50°C under dry and wet conditions by applying a constant torque for static and creep testing and dynamic torsional loading for dynamic testing. Degree of conversion (%DC) was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Statistical analysis was performed with two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient. Shear modulus G ranged from 2.17GPa (VE) to 8.03GPa (XF) and flexural modulus E from 6.16GPa (VE) to 23GPa (XF) when the materials were tested dry at 21°C. The increase of temperature and the presence of water lead to a decline of these properties. Flowable materials used as base composites in restorations showed significantly lower values (p<0.05) than non-base composites, while being more prone to creep deformation. %DC ranged from 47.25% (XF) to 66.67% (SD) at the top material surface and 36.06% (XF) to 63.20% (SD) at the bottom. Bulk fill composites exhibited significant differences between them with base flowable materials showing in most cases inferior mechanical properties and higher degree of conversion than restorative bulk fill materials. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Mirone, Giuseppe; Marton, B.; Marton, Beáta; Vancso, Gyula J.
2004-01-01
The temporal development of the modulus of elasticity and its profile were studied in water-borne alkyd coatings during the drying process of the coating films. Values of the Young’s moduli of elasticity of free coating films were measured using tensile tests. Since the elastic modulus is related to
Variation of Hardness and Modulus across thickness of Zr-Cu-Al Metallic Glass Ribbons
Z. Humberto Melgarejo; J.E. Jakes; J. Hwang; Y.E. Kalay; M.J. Kramer; P.M. Voyles; D.S. Stone
2012-01-01
We investigate through-thickness hardness and modulus of Zr50Cu45Al5 metallic glass melt-spun ribbon. Because of their thinness, the ribbons are challenging to measure, so we employ a novel nanoindentation based-method to remove artifacts caused by ribbon flexing and edge effects. Hardness and modulus...
Estimation of the Young’s modulus of cellulose Iß by MM3 and quantum mechanics
Young’s modulus provides a measure of the resistance to deformation of an elastic material. In this study, modulus estimations for models of cellulose Iß relied on calculations performed with molecular mechanics (MM) and quantum mechanics (QM) programs. MM computations used the second generation emp...
Resilient modulus characteristics of soil subgrade with geopolymer additive in peat
Zain, Nasuhi; Hadiwardoyo, Sigit Pranowo; Rahayu, Wiwik
2017-06-01
Resilient modulus characteristics of peat soil are generally very low with high potential of deformation and low bearing capacity. The efforts to improve the peat subgrade resilient modulus characteristics is required, one among them is by adding the geopolymer additive. Geopolymer was made as an alternative to replace portland cement binder in the concrete mix in order to promote environmentally friendly, low shrinkage value, low creep value, and fire resistant material. The use of geopolymer to improve the mechanical properties of peat as a road construction subgrade, hence it becomes important to identify the effect of geopolymer addition on the resilient modulus characteristics of peat soil. This study investigated the addition of 0% - 20% geopolymer content on peat soil derived from Ogan Komering Ilir, South Sumatera Province. Resilient modulus measurement was performed by using cyclic triaxial test to determine the resilience modulus model as a function of deviator stresses and radial stresses. The test results showed that an increase in radial stresses did not necessarily lead to an increase in modulus resilient, and on the contrary, an increase in deviator stresses led to a decrease in modulus resilient. The addition of geopolymer in peat soil provided an insignificant effect on the increase of resilient modulus value.
Approximation of classes of functions defined by a generalized $r$-th modulus of smoothness
Potapov, Mikhail K.; Berisha, Faton M.
2012-01-01
In this paper, a $k$-th generalized modulus of smoothness is defined based on an asymmetric operator of generalized translation and a theorem is proved about the coincidence of class of functions defined by this modulus and a class of functions having given order of best approximation by algebraic polynomials.
Pongprueksa, Pong; Senawongse, Pisol; Vongphan, Nataya
2014-01-01
The effect of tubule orientation of dentin on the elastic modulus of resin-infiltrated dentin was evaluated. Rectangular cylindricalshaped dentin specimens with their long axis parallel to and perpendicular to dentinal tubules were prepared from extracted premolars. Twenty-five mineralized specimens of each orientation were evaluated. The remaining specimens were then demineralized. The demineralized specimens and the demineralized following by infiltration with one of these adhesives; Optibond Solo Plus, Single Bond 2 or Prime & Bond NT, from each orientation were evaluated (25 specimens per group). The tubular orientation only affected the elastic modulus of mineralized dentin. The highest elastic modulus was observed for the mineralized dentin when the tensile force was applied parallel to the direction of tubules. The elastic modulus of demineralized dentin was the lowest. The adhesive resins increased the elastic modulus of demineralized dentin, but the differences among the three were insignificant.
A regularization-free Young's modulus reconstruction algorithm for ultrasound elasticity imaging.
Pan, Xiaochang; Gao, Jing; Shao, Jinhua; Luo, Jianwen; Bai, Jing
2013-01-01
Ultrasound elasticity imaging aims to reconstruct the distribution of elastic modulus (e.g., Young's modulus) within biological tissues, since the value of elastic modulus is often related to pathological changes. Currently, most elasticity imaging algorithms face a challenge of choosing the value of the regularization constant. We propose a more applicable algorithm without the need of any regularization. This algorithm is not only simple to use, but has a relatively high accuracy. Our method comprises of a nonrigid registration technique and tissue incompressibility assumption to estimate the two-dimensional (2D) displacement field, and finite element method (FEM) to reconstruct the Young's modulus distribution. Simulation and phantom experiments are performed to evaluate the algorithm. Simulation and phantom results showed that the proposed algorithm can reconstruct the Young's modulus with an accuracy of 63∼85%.
Directory of Open Access Journals (Sweden)
Muhammad Ridwan
2017-01-01
Full Text Available Bricks of low elastic modulus are occasionally used in some developing countries, such as Indonesia and India. Most of the previous research efforts focused on masonry structures built with bricks of considerably high elastic modulus. The objective of this study is to quantify the equivalent elastic modulus of lower-stiffness masonry structures, when the mortar has a higher modulus of elasticity than the bricks, by employing finite element (FE simulations and adopting the homogenization technique. The reported numerical simulations adopted the two-dimensional representative volume elements (RVEs using quadrilateral elements with four nodes. The equivalent elastic moduli of composite elements with various bricks and mortar were quantified. The numerically estimated equivalent elastic moduli from the FE simulations were verified using previously established test data. Hence, a new simplified formula for the calculation of the equivalent modulus of elasticity of such masonry structures is proposed in the present study.
A Prediction Method of Tensile Young's Modulus of Concrete at Early Age
Directory of Open Access Journals (Sweden)
Isamu Yoshitake
2012-01-01
Full Text Available Knowledge of the tensile Young's modulus of concrete at early ages is important for estimating the risk of cracking due to restrained shrinkage and thermal contraction. However, most often, the tensile modulus is considered equal to the compressive modulus and is estimated empirically based on the measurements of compressive strength. To evaluate the validity of this approach, the tensile Young's moduli of 6 concrete and mortar mixtures are measured using a direct tension test. The results show that the tensile moduli are approximately 1.0–1.3-times larger than the compressive moduli within the material's first week of age. To enable a direct estimation of the tensile modulus of concrete, a simple three-phase composite model is developed based on random distributions of coarse aggregate, mortar, and air void phases. The model predictions show good agreement with experimental measurements of tensile modulus at early age.
Laboratory Performance Evaluation of High Modulus Asphalt Concrete Modified with Different Additives
Directory of Open Access Journals (Sweden)
Peng Li
2017-01-01
Full Text Available The objective of this study is to evaluate comprehensive performance of high modulus asphalt concrete (HMAC and propose common values for establishing evaluation system. Three gradations with different modifiers were conducted to study the high and low temperature performance, shearing behavior, and water stability. The laboratory tests for HMAC included static and dynamic modulus tests, rutting test, uniaxial penetration test, bending test, and immersion Marshall test. Dynamic modulus test results showed that modifier can improve the static modulus and the improvements were remarkable at higher temperature. Moreover, modulus of HMAC-20 was better than those of HMAC-16 and HMAC-25. The results of performance test indicated that HMAC has good performance to resist high temperature rutting, and the resistances of the HMAC-20 and HMAC-25 against rutting were better than that of HMAC-16. Then, the common values of dynamic stability were recommended. Furthermore, common values of HMAC performance were established based on pavement performance tests.
Detection of placenta elasticity modulus by quantitative real-time shear wave imaging.
Li, W J; Wei, Z T; Yan, R L; Zhang, Y L
2012-01-01
To explore the clinical values in detecting the placental elastic modulus using real-time quantitative shear wave elasticity imaging. A total of 30 women in the late pregnancy stage without complications and having normal, single pregnancies, as well as normal fetal growth, amniotic fluid index, and anterior placenta were selected. A real-time elasticity imaging shear wave ultrasonic diagnostic apparatus was used to randomly select regions of interest at the central and edge of the placenta. The elastography imaging mode was launched to measure the elasticity of the elastic modulus of these placental parts. A total of 15 measured values were obtained at the placental center and edge for each pregnancy case. Umbilical artery and uterine artery pulsatility index (PI) values for 18 cases were also randomly measured. The average value of 30 placental edges of the elastic modulus (n = 15) was (7.60 +/- 1.71) kPa. The average value of the 30 placental central elastic modulus (n = 15 ) was (7.84 +/- 1.68) kPa. No significant difference was observed between placenta central and edge elastic modulus. The PI mean value of umbilical artery in 18 cases was 0.94, whereas the average PI values of the uterine artery was 0.83. No linear correlation was found among the elastic modulus, the placental uterine artery PI values, and the umbilical artery PI values (p > 0.05). No difference between the placental center of normal pregnancies and the edge of the elastic modulus was detected. The elastic modulus of the placenta could be obtained in the best position. The placenta varied greatly between elastic modulus. No correlation was found between the placental elastic modulus, the uterine artery, and umbilical artery PI values. Real-time shear wave elasticity imaging technology can provide morphological evidence of placental function, which may emerge as a new clinical assessment approach.
Fabrication of Bulk Glassy Alloy Foams by High Pressure Hydrogen
Wada, Takeshi; Inoue, Akihisa
Porous Pd42.5Cu30Ni7.5P20 bulk glassy alloy rods with porosities of up to 70% were successfully prepared by high pressure hydrogen of 15 MPa. The melt of Pd42.5Cu30Ni7.5P20 alloy kept under high pressure hydrogen absorbs hydrogen and subsequent water quenching of the melt causes the homogeneous dispersion of hydrogen bubbles, which was resulted from the decrease of hydrogen solubility with decrease of pressure. Annealing the hydrogen bubble containing sample at a supercooled liquid state under vacuum, the bubbles are allowed to expand due to the decrease of viscosity of metallic glass matrix. Pores expansion continues until glassy matrix crystallizes or the equilibration among pressure of the pores, pressure of the atmosphere and surface tension is achieved. By utilizing these phenomena, pores up to 80 m in diameters are homogeneously distributed over the whole cross-sectional area of a fully glassy matrix. Under compressive deformation, the porous alloys with porosities exceeding 40% did not show macroscopic fracture in a wide compressive strain range up to 0.6 whereas the non-porous alloy fractures instantly after elastic limit of about 0.02. Porous bulk glassy alloys exhibit higher plateau stress, lower Young‧s modulus and higher energy absorption capacity compared with the conventional crystalline metal foams.
Bulk density of small meteoroids
Kikwaya, J.-B.; Campbell-Brown, M.; Brown, P. G.
2011-06-01
Aims: Here we report on precise metric and photometric observations of 107 optical meteors, which were simultaneously recorded at multiple stations using three different intensified video camera systems. The purpose is to estimate bulk meteoroid density, link small meteoroids to their parent bodies based on dynamical and physical density values expected for different small body populations, to better understand and explain the dynamical evolution of meteoroids after release from their parent bodies. Methods: The video systems used had image sizes ranging from 640 × 480 to 1360 × 1036 pixels, with pixel scales from 0.01° per pixel to 0.05° per pixel, and limiting meteor magnitudes ranging from Mv = +2.5 to +6.0. We find that 78% of our sample show noticeable deceleration, allowing more robust constraints to be placed on density estimates. The density of each meteoroid is estimated by simultaneously fitting the observed deceleration and lightcurve using a model based on thermal fragmentation, conservation of energy and momentum. The entire phase space of the model free parameters is explored for each event to find ranges of parameters which fit the observations within the measurement uncertainty. Results: (a) We have analysed our data by first associating each of our events with one of the five meteoroid classes. The average density of meteoroids whose orbits are asteroidal and chondritic (AC) is 4200 kg m-3 suggesting an asteroidal parentage, possibly related to the high-iron content population. Meteoroids with orbits belonging to Jupiter family comets (JFCs) have an average density of 3100 ± 300 kg m-3. This high density is found for all meteoroids with JFC-like orbits and supports the notion that the refractory material reported from the Stardust measurements of 81P/Wild 2 dust is common among the broader JFC population. This high density is also the average bulk density for the 4 meteoroids with orbits belonging to the Ecliptic shower-type class (ES) also
Age-related changes in hardness and modulus of elasticity of dentine.
Senawongse, Pisol; Otsuki, Masayuki; Tagami, Junji; Mjör, Ivar
2006-06-01
Little knowledge has been clarified about the relationship between the morphological and physical changes of dentine during aging. The purpose of this study was to clarify the modulus of elasticity and hardness related to the morphological changes of dentine by aging using a transmitted light microscope (TLM) and a nano-hardness tester (NHT). Aged human molars and young third molars were used. The dentine morphology was observed under a TLM. The hardness and Young's modulus of elasticity related to the morphologic study were evaluated with an NHT. The thickness of mantle dentine and globular dentine of aged teeth were less than that of young teeth. Transparent dentine was observed only underneath the attrition of young teeth. Reactionary tertiary dentine formed and a "dark zone" was found at the junction between physiologic secondary and reactionary dentine only in aged teeth. At the mantle dentine, hardness and modulus of elasticity of aged dentine were higher than those of young dentine. The reactionary dentine in aged teeth and newly developed secondary dentine in young teeth demonstrated lower modulus of elasticity and hardness than those of other circumpulpal dentine. Relatively low modulus of elasticity and hardness were observed at the zone between secondary and reactionary dentine. Changes in dentine due to aging resulted in transformation of morphological features causing changes to their hardness and modulus of elasticity at the explicit areas such as the increase of hardness and modulus of elasticity at mantle dentin and the reduction of these properties at the "dark zone" that found in aged teeth.
Effects of resin hydrophilicity on water sorption and changes in modulus of elasticity.
Ito, Shuichi; Hashimoto, Masanori; Wadgaonkar, Bakul; Svizero, Nadia; Carvalho, Ricardo M; Yiu, Cynthia; Rueggeberg, Frederick A; Foulger, Stephen; Saito, Takashi; Nishitani, Yoshihiro; Yoshiyama, Masahiro; Tay, Franklin R; Pashley, David H
2005-11-01
As acidic monomers of self-etching adhesives are incorporated into dental adhesives at high concentrations, the adhesive becomes more hydrophilic. Water sorption by polymers causes plasticization and lowers mechanical properties. The purpose of this study was to compare the water sorption and modulus of elasticity (E) of five experimental neat resins (EX) of increasing hydrophilicity, as ranked by their Hoy's solubility parameters and five commercial resins. After measuring the initial modulus of all resin disks by biaxial flexure, half the specimens were stored in hexadecane and the rest were stored in water. Repeated measurements of stiffness were made for 3 days. Water sorption and solubility measurements were made in a parallel experiment. None of the specimens stored in oil showed any significant decrease in modulus. All resins stored in water exhibited a time-dependent decrease in modulus that was proportional to their degree of water sorption. Water sorption of EX was proportional to Hoy's solubility parameter for polar forces (delta(p)) with increasing polarity resulting in higher sorption. The least hydrophilic resin absorbed 0.55 wt% water and showed a 15% decrease in modulus after 3 days. The most hydrophilic experimental resin absorbed 12.8 wt% water and showed a 73% modulus decrease during the same period. The commercial resins absorbed between 5% and 12% water that was associated with a 19-42% reduction in modulus over 3 days.
Reliable measurement of elastic modulus of cells by nanoindentation in an atomic force microscope
Zhou, Zhoulong
2012-04-01
The elastic modulus of an oral cancer cell line UM1 is investigated by nanoindentation in an atomic force microscope with a flat-ended tip. The commonly used Hertzian method gives apparent elastic modulus which increases with the loading rate, indicating strong effects of viscoelasticity. On the contrary, a rate-jump method developed for viscoelastic materials gives elastic modulus values which are independent of the rate-jump magnitude. The results show that the rate-jump method can be used as a standard protocol for measuring elastic stiffness of living cells, since the measured values are intrinsic properties of the cells. © 2011 Elsevier Ltd.
Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation
Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.
2002-01-01
The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.
E-modulus evolution and its relation to solids formation of pastes from commercial cements
DEFF Research Database (Denmark)
Maia, Lino; Azenha, Miguel; Geiker, Mette
2012-01-01
developed methodology allowed continuous monitoring of E-modulus from the time of casting. The methodology is a variant of classic resonant frequency methods, which are based on determination of the first resonant frequency of a composite beam containing the material. The hydration kinetics — and thus...... the rate of formation of solids — was determined using chemical shrinkage measurements. For the cements studied similar relationships between E-modulus and chemical shrinkage were observed for comparable water-to-binder ratio. For commercial cements it is suggested to model the E-modulus evolution based...
Quantitative Study of the Elastic Modulus of Loosely Attached Cells in AFM Indentation Experiments
Dokukin, Maxim E.; Guz, Nataliia V.; Sokolov, Igor
2013-01-01
When measuring the elastic (Young’s) modulus of cells using AFM, good attachment of cells to a substrate is paramount. However, many cells cannot be firmly attached to many substrates. A loosely attached cell is more compliant under indenting. It may result in artificially low elastic modulus when analyzed with the elasticity models assuming firm attachment. Here we suggest an AFM-based method/model that can be applied to extract the correct Young’s modulus of cells loosely attached to a subs...
Bulk Moisture and Salinity Sensor
Nurge, Mark; Monje, Oscar; Prenger, Jessica; Catechis, John
2013-01-01
Measurement and feedback control of nutrient solutions in plant root zones is critical to the development of healthy plants in both terrestrial and reduced-gravity environments. In addition to the water content, the amount of fertilizer in the nutrient solution is important to plant health. This typically requires a separate set of sensors to accomplish. A combination bulk moisture and salinity sensor has been designed, built, and tested with different nutrient solutions in several substrates. The substrates include glass beads, a clay-like substrate, and a nutrient-enriched substrate with the presence of plant roots. By measuring two key parameters, the sensor is able to monitor both the volumetric water content and salinity of the nutrient solution in bulk media. Many commercially available moisture sensors are point sensors, making localized measurements over a small volume at the point of insertion. Consequently, they are more prone to suffer from interferences with air bubbles, contact area of media, and root growth. This makes it difficult to get an accurate representation of true moisture content and distribution in the bulk media. Additionally, a network of point sensors is required, increasing the cabling, data acquisition, and calibration requirements. measure the dielectric properties of a material in the annular space of the vessel. Because the pore water in the media often has high salinity, a method to measure the media moisture content and salinity simultaneously was devised. Characterization of the frequency response for capacitance and conductance across the electrodes was completed for 2-mm glass bead media, 1- to 2-mm Turface (a clay like media), and 1- to 2-mm fertilized Turface with the presence of root mass. These measurements were then used to find empirical relationships among capacitance (C), the dissipation factor (D), the volumetric water content, and the pore water salinity.
Gold based bulk metallic glass
Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan
2005-01-01
Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5 mm in the best glassformer. Au49Ag5.5Pd2.3Cu26.9Si16.3 has a liquidus temperature of 644 K, a glass transition temperature of 401 K, and a supercooled liquid region of 58 K. The Vickers hardness of the alloys in this system...
National Research Council Canada - National Science Library
Adachi, Hiromasa; Hasegawa, Teruo
2004-01-01
For evaluation of thermal endurance in foamed plastics, temperature and time characteristics of compression dynamic modulus of four hard polyurethane foams were investigated by the dynamic viscoelastic measurements...
Elastic modulus of diamond-like carbon films prepared by pulsed vacuum arc
Schultrich, B.; Scheibe, H.-J.; Grandremy, G.; Schneider, D.; Siemroth, P.
1994-12-01
Amorphous carbon films have been prepared by special pulsed vacuum arc depositon methods allowing high currents up to 1 kA and more. The Young's modulus of these films has been determined with respect to various technological parameters. For these measurements a method based on the propagation of ultrasonic surface waves has been applied which has been specially designed for the investigation of thin films below one micrometer. Large changes of the elastic modulus, depending on the technology, have been observed, contrasting with the common understanding of invariability of the elastic behavior. Reflecting the large structural variations possible in amorphous carbon, the elastic modulus represents a suitable parameter for characterizing the carbon-carbon network. Furthermore, the elastic modulus of amorphous carbon films may be used for a first estimation of film hardness because of the strong correlation of these two quantities.
Satoh, Youji; Fujii, Shuji; Kawahara, Seiichi; Isono, Yoshinobu; Kagami, Shigeru
Correspondence between nonlinear viscoelastic properties and change in various networks in carbon black (CB) filled, uncured SBRs has been studied by using combined measurements of relaxation modulus, differential dynamic modulus, and volume resisitivity in wide range of filler concentrations at various shear strains. Volume resistivity at no deformation showed step-off like change which can be explained by the percolation theory. This indicates formation of contact filler network at high filler loading. In addition, change in volume resistivity showed clear correspondence with linear-nonlinear transition in viscoelasticity. By the use of simple three-network model, contributions of contact filler, bridged filler, and entanglement networks to relaxation modulus were estimated. It was found that contact filler and bridged filler networks were dominant at lower and at higher filler concentrations, respectively. It was proposed, furthermore, that differential dynamic modulus can be used as the probes for changes in contact filler and bridged filler networks, respectively.
Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Modulus
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...
Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Modulus
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...
Mechanical properties of concrete with SAP. Part II: Modulus of elasticity
DEFF Research Database (Denmark)
Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede
2010-01-01
of air voids. Second, SAP addition may at the same time lead to increased compressive strength (as shown in [5]) and reduced E-modulus. A prediction based solely on compressive strength therefore overrates the modulus of elasticity, so the empirical models are unsafe to use for concrete with SAP......, and air with volume fractions of the three phases as well as elastic properties of paste and aggregates as input parameters. Addition of SAP changes the E-modulus, because it both has an influence on properties of the cement paste and on the volume of air voids. Here, the E-modulus is an example...... of a mechanical property, and the same methodology can probably be applied to other mechanical properties. It is often assumed that a range of mechanical properties of concrete can be derived if the compressive strength is known. The link between the compressive strength and other mechanical properties is often...
National Research Council Canada - National Science Library
Mulian Zheng; Lili Han; Chongtao Wang; Zhanlei Xu; Hongyin Li; Qinglei Ma
2017-01-01
.... Based on the creep test, the Prony series representation of Burgers model parameters for different asphalt mixtures were obtained and used in the deformation simulation of a high-modulus asphalt...
Resilient modulus for unbound granular materials and subgrade soils in Egypt
Directory of Open Access Journals (Sweden)
Mousa Rabah
2017-01-01
Full Text Available Mechanistic Empirical (ME pavement design methods started to gain attention especially the last couple of years in Egypt and the Middle East. One of the challenges facing the spread of these methods in Egypt is lack of advanced properties of local soil and asphalt, which are needed as input data in ME design. Resilient modulus (Mr for example is an important engineering property that expresses the elastic behavior of soil/unbound granular materials (UGMs under cyclic traffic loading for ME design. In order to overcome the scarcity of the resilient modulus data for soil/UGMs in Egypt, a comprehensive laboratory testing program was conducted to measure resilient modulus of typical UGMs and subgrade soils typically used in pavement construction in Egypt. The factors that affect the resilient modulus of soil/UGMs were reviewed, studied and discussed. Finally, the prediction accuracy of the most well-known Mr Prediction models for the locally investigated materials was investigated.
Measurement of elastic modulus and evaluation of viscoelasticity of foundry green sand
Directory of Open Access Journals (Sweden)
Qingchun XIANG
2004-08-01
Full Text Available Elastic modulus is an important physical parameter of molding sand; it is closely connected with molding sand's properties. Based on theories of rheology and molding sand microdeformation, elastic modulus of molding sand was measured and investigated using the intelligent molding sand multi-property tester developed by ourselves. The measuring principle was introduced. Effects of bentonite percentage and compactibility of the molding sand were experimentally studied. Furthermore, the essential viscoelastic nature of green sand was analyzed. It is considered that viscoelastic deformation of molding sand consists mainly of that of Kelvin Body of clay membrane, and elastic modulus of molding sand depends mainly on that of Kelvin Body which is the elastic component of clay membrane between sands. Elastic modulus can be adopted as one of the property parameters, and can be employed to evaluate viscoelastic properties of molding sand.
Design values of resilient modulus of stabilized and non-stabilized base.
2010-10-01
The primary objective of this research study is to determine design value ranges for typical base materials, as allowed by LADOTD specifications, through laboratory tests with respect to resilient modulus and other parameters used by pavement design ...
Unaffected nonclassical response of solid 4He under elastic modulus variation
Kim, D. Y.; Choi, H.; Choi, W.; Kwon, S.; Kim, E.; Kim, H. C.
2011-02-01
The superflow in solid helium was detected by a decrease in the resonant period of a torsional oscillator (TO) below 0.2 K. Recently, the shear modulus of solid helium has shown an unusual increase with a striking resemblance to those of the TO anomaly. The similarities have invigorated alternative nonsuperfluid explanations for the decrease in the period. Here, we report the influence of the shear modulus change on the resonant period of the TO to examine the fundamental connection between the two phenomena. The period of TO that exhibits quantitatively different drive dependence is not susceptible to the elastic modulus change, indicating that the microscopic origin of the TO anomaly is different from the shear modulus change.
Direct and inverse theorems of approximation theory for a generalised modulus of smoothness
Potapov, Mikhail K.; Berisha, Faton M.
2012-01-01
An asymmetric operator of generalised translation is introduced in this paper. Using this operator, we define a generalised modulus of smoothness and prove direct and inverse theorems of approximation theory for it.
Wind Diffusivity Current, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Modulus
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...
Shear elastic modulus of magnetic gels with random distribution of magnetizable particles
Iskakova, L. Yu; Zubarev, A. Yu
2017-04-01
Magnetic gels present new type of composite materials with rich set of uniquie physical properties, which find active applications in many industrial and bio-medical technologies. We present results of mathematically strict theoretical study of elastic modulus of these systems with randomly distributed magnetizable particles in an elastic medium. The results show that an external magnetic field can pronouncedly increase the shear modulus of these composites.
Xu, Qinwu; Engquist, Bjorn
2014-01-01
We propose a new material viscoelastic model and mathematical solution to simulate relaxation modulus and viscoelastic response. The model formula of relaxation modulus is extended from sigmoidal function considering nonlinear strain hardening and softening. Its physical mechanism can be interpreted by a spring network viscous medium model with only five parameters in a simpler format than the molecular-chain based polymer models to represent general materials. We also developed a three-dimen...
A low elastic modulus Ti-Nb-Hf alloy bioactivated with an elastin-like
González, Marta; Salvagni, Emiliano; Rodríguez Cabello, J.C.; Rupérez de Gracia, Elisa; Gil Mur, Francisco Javier; Manero Planella, José María; Peña, Javier
2012-01-01
b-type titanium alloys with low Young’s modulus are desirable to reduce stress shielding effect and enhance bone remodeling for implants used to substitute failed hard tissue. For biomaterials application, the surface bioactivity is necessary to achieve optimal osseointegration. In the previous work, the low elastic modulus (43 GPa) Ti-25Nb-16Hf (wt %) alloy was mechanically and microstructurally characterized. In the present work, the biological behavior of Ti-25Nb- 1...
Directory of Open Access Journals (Sweden)
F.J. Quiñones-N
2014-01-01
Full Text Available In this work a simplified low-frequency resonant method for the measurement of Young’s modulus of polysilicon cantilevers is described. We used a test chip, specially designed for characterizing thermal and mechanical properties, and fabricated using a combined bulk/surface micromachining process. In this regard, an opto-mechanical set up for the measurement of Young’s modulus is described. We use this set up for the characterization of 50 μm-wide, 1.0 μm-thick and 200–325 μm-long polysilicon cantilevers, under a mechanical excitation in the kHz frequency range.
Modulus Ratio and Joint Factor Concepts to Predict Rock Mass Response
Ramamurthy, T.; Latha, G. Madhavi; Sitharam, T. G.
2017-02-01
The commonly adopted rock mass classifications, namely RMR, Q and GSI, are used to estimate compressive strength and modulus of rock masses. These values have been examined as per modulus ratio concept, M rj , for their reliability. The design parameters adopted in some of the recent case studies based on these classifications indicate that the M rj values for rock masses are higher than those of the corresponding intact rocks. The joint factor, J f, which is defined as a weakness coefficient in rock mass suggests that modulus ratio of rock mass ( M rj ) has to be less than the modulus ratio of the corresponding intact rock ( M ri ), on the basis of extensive experimental evidence. With joint factor, compressive strength, elastic modulus, cohesion and friction angle were estimated and applied in the analyses of a few cases. The predictions of deformations with this approach agreed well with the field measurements by adapting equivalent continuum approach. The modulus ratio concept is considered to present a unified classification for intact rocks and rock masses. Soil-rock boundary, standup time in under ground excavations and also penetration rate of TBM estimates have been linked to M rj .
Developing the elastic modulus measurement of asphalt concrete using the compressive strength test
Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik
2017-11-01
Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.
Geometrical modulus of a casting and its influence on solidification process
Directory of Open Access Journals (Sweden)
F. Havlicek
2011-10-01
Full Text Available Object: The work analyses the importance of the known criterion for evaluating the controlled solidification of castings, so called geometrical modulus defined by N. Chvorinov as the first one. Geometrical modulus influences the solidification process. The modulus has such specificity that during the process of casting formation it is not a constant but its initial value decreases with the solidification progress because the remaining melt volume can decrease faster than its cooling surface.Methodology: The modulus is determined by a simple calculation from the ratio of the casting volume after pouring the metal in the mould to the cooled mould surface. The solidified metal volume and the cooled surface too are changed during solidification. That calculation is much more complicated. Results were checked up experimentally by measuring the temperatures in the cross-section of heavy steel castings during cooling them.Results: The given experimental results have completed the original theoretical calculations by Chvorinov and recent researches done with use of numerical calculations. The contribution explains how the geometrical modulus together with the thermal process in the casting causes the higher solidification rate in the axial part of the casting cross-section and shortening of solidification time. Practical implications: Change of the geometrical modulus negatively affects the casting internal quality. Melt feeding by capillary filtration in the dendritic network in the casting central part decreases and in such a way the shrinkage porosity volume increases. State of stress character in the casting is changed too and it increases.
Handling of bulk solids theory and practice
Shamlou, P A
1990-01-01
Handling of Bulk Solids provides a comprehensive discussion of the field of solids flow and handling in the process industries. Presentation of the subject follows classical lines of separate discussions for each topic, so each chapter is self-contained and can be read on its own. Topics discussed include bulk solids flow and handling properties; pressure profiles in bulk solids storage vessels; the design of storage silos for reliable discharge of bulk materials; gravity flow of particulate materials from storage vessels; pneumatic transportation of bulk solids; and the hazards of solid-mater
Fabricating Zr-Based Bulk Metallic Glass Microcomponent by Suction Casting Using Silicon Micromold
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Zhijing Zhu
2014-08-01
Full Text Available A suction casting process for fabricating Zr55Cu30Al10Ni5 bulk metallic glass microcomponent using silicon micromold has been studied. A complicated BMG microgear with 50 μm in module has been cast successfully. Observed by scanning electron microscopy and laser scanning confocal microscopy, we find that the cast microgear duplicates the silicon micromold including the microstructure on the surface. The amorphous state of the microgear is confirmed by transmission election microscopy. The nanoindentation hardness and elasticity modulus of the microgear reach 6.5 GPa and 94.5 GPa. The simulation and experimental results prove that the suction casting process with the silicon micromold is a promising one-step method to fabricate bulk metallic glass microcomponents with high performance for applications in microelectromechanical system.
Elastic modulus in rigid Al{sub 2}O{sub 3}/ZrO{sub 2} ceramic laminates
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Moya, J.S.; Sanchez-Herencia, J.A.; Bartolome, J.F. [CSIC, Madrid (Spain). Inst. de Ciencia de Materiales; Tanimoto, T. [Shonan Inst. of Tech., Fujisawa, Kanagawa (Japan)
1997-10-01
In previous works it has been shown that by making a three-layer composite in which the central region contains the matrix oxide and stabilized zirconia and the surface layers contain the matrix oxide and unstabilized zirconia, strength can be substantially enhanced relative to the monolithic materials containing the oxide matrix and either stabilized or unstabilized zirconia. The magnitude of the surface compressive stresses can be varied controlling the thickness of the outer layers and by proper thermal treatment in which the relative amounts of the monoclinic and tetragonal phases in the outer layers are controlled or by varying the volume fraction of total zirconia in the component. Often, the residual stresses are tailored to obtain high surface compression and a moderate bulk tension. In the present investigation, the authors have studied the effects of macroscopic residual stresses on stress intensities in the different layers of the Al{sub 2}O{sub 3}/ZrO{sub 2} laminates and the influence of the layered design on the elastic modulus of these materials.
Shibasaki, S; Takamizawa, T; Nojiri, K; Imai, A; Tsujimoto, A; Endo, H; Suzuki, S; Suda, S; Barkmeier, W W; Latta, M A; Miyazaki, M
The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m 3 . There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and
Measurement of the Young’s modulus using micro-cantilevered beam actuated by electrostatic force
Wang, Zhichong; Zhang, Qichang; Wang, Chen
2018-02-01
Determining the Young’s modulus accurately is important in micro-electro-mechanical systems (MEMS) design. Generally, the Young’s modulus of a micro-component is measured by the resonance method, of which the actuation is electrostatic force. However, this method does not take the effect of the electrostatic force on the resonant frequency into consideration. Thus, the test error becomes more obvious as the DC voltage increases. In this paper, an improved resonance method, determining the Young’s modulus of a micro-cantilever beam, is proposed, which takes the nonlinearity of the electrostatic force into consideration. This method has three obvious advantages: only one simple micro-cantilevered beam sample is needed; it is unnecessary to find the initial thickness of the gas film between the beam and the substrate; the accuracy of the measurement result of the Young’s modulus is improved. In order to obtain the resonant frequency of a cantilevered beam actuated by a DC voltage, the dynamic equations of the micro-cantilevered beam in multi-field coupled situations are established, and the effect of the electrostatic force on the resonant frequency of the micro-beam is investigated. Results show that, the Young’s modulus can be found by measuring the resonant frequency and DC voltage. The dynamics performances of the micro-structure are influenced by the nonlinearity of the electrostatic force, and the electrostatic effect should be observed especially when the beam becomes smaller, through general studies. Finally, the experimental principle of measuring the Young’s modulus is designed and conducted to verify these theories. The Young’s modulus of brass is measured exactly.
Zelisko, Matthew; Ahmadpoor, Fatemeh; Gao, Huajian; Sharma, Pradeep
2017-08-01
The dominant deformation behavior of two-dimensional materials (bending) is primarily governed by just two parameters: bending rigidity and the Gaussian modulus. These properties also set the energy scale for various important physical and biological processes such as pore formation, cell fission and generally, any event accompanied by a topological change. Unlike the bending rigidity, the Gaussian modulus is, however, notoriously difficult to evaluate via either experiments or atomistic simulations. In this Letter, recognizing that the Gaussian modulus and edge tension play a nontrivial role in the fluctuations of a 2D material edge, we derive closed-form expressions for edge fluctuations. Combined with atomistic simulations, we use the developed approach to extract the Gaussian modulus and edge tension at finite temperatures for both graphene and various types of lipid bilayers. Our results possibly provide the first reliable estimate of this elusive property at finite temperatures and appear to suggest that earlier estimates must be revised. In particular, we show that, if previously estimated properties are employed, the graphene-free edge will exhibit unstable behavior at room temperature. Remarkably, in the case of graphene, we show that the Gaussian modulus and edge tension even change sign at finite temperatures.
Directory of Open Access Journals (Sweden)
S. S. Araújo
Full Text Available This paper presents a comparative analysis of the results obtained in static modulus of elasticity tests of plain concrete cylindrical specimens. The purpose of this study is to identify and evaluate the influence of several factors involved in modulus of elasticity tests such as the strain measurement device used (dial indicators, electrical surface bonded strain gages, externally fixed strain gages and linear variation displacement transducer - LVDT, the type of concrete (Class C30 and Class C60 and cylindrical specimen size (100 mm x 200 mm and 150 mm x 300 mm. The modulus tests were done in two different laboratories in the Goiânia, GO region and were performed according to code ABNT NBR 8522:2008, which describes the initial tangent modulus test, characterized by strains measured at tension values of 0.5 MPa and 30% of the ultimate load. One hundred and sixty specimens were tested with statistically satisfactory results. It was concluded that the type of strain measurement device greatly influenced the modulus of elasticity results. Tests in specimens 100 mm x 200 mm showed highest statistical variation.
Linear Correlation Between Binding Energy and Young’s Modulus in Graphene Nanoribbons
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Zeinalipour-Yazdi, Constantinos D.; Christofides, Constantinos
2009-09-15
Graphene nanoribbons (GNRs) have been suggested as a promising material for its use as nanoelectromechanical reasonators for highly sensitive force, mass, and charge detection. Therefore the accurate determination of the size-dependent elastic properties of GNRs is desirable for the design of graphene-based nanoelectromechanical devices. In this study we determine the size-dependent Young’s modulus and carbon-carbon binding energy in a homologous series of GNRs, C4n2+6n+2H6n+4 (n=2–12), with the use of all electron first principles computations. An unexpected linearity between the binding energy and Young’s modulus is observed, making possible the prediction of the size-dependent Young’s modulus of GNRs through a single point energy calculation of the GNR ground state. A quantitative-structure-property relationship is derived, which correlates Young’s modulus to the total energy and the number of carbon atoms within the ribbon. In the limit of extended graphene sheets we determine the value of Young’s modulus to be 1.09 TPa, in excellent agreement with experimental estimates derived for graphite and suspended grapheme sheets.
Albert, Julie N. L.; Genzer, Jan
2013-03-01
Biocompatible silicone elastomer networks provide a versatile platform for studying the effect of compliance on cell movement. In conventional network formation schemes, poly(dimethylsiloxane) (PDMS) is cross-linked via reactive end groups, and the modulus of the material is controlled by the ratio of polymer to cross-linker. However, low modulus networks fabricated in this manner are imperfect and insufficiently cross-linked with high soluble fractions and reduced elasticity, especially as the network modulus approaches that of soft tissues (on the order of 10 kPa). In order to overcome these limitations, we synthesized PDMS chains in which vinylmethylsiloxane units were incorporated every ~15-20 kDa along the polymer backbone. We then cross-linked the polymer through the vinyl groups using hydrosilylation chemistry. The resultant networks exhibited lower soluble fractions and lower viscous dissipation/greater elasticity as compared to equivalent-modulus networks fabricated by the conventional end-group cross-linking scheme. We attribute the mechanical properties of our networks to the presence of network-bound free chain ends that effectively plasticize the network to lower the modulus without compromising network elasticity.
The effect of fluid saturation on the dynamic shear modulus of tight sandstones
Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Shuai, Da
2017-10-01
Tight sandstones have become important targets in the exploration of unconventional oil and gas reservoirs. However, due to low porosity, low permeability, complex pore structure and other petrophysical properties of tight sandstones, the applicability of Gassmann’s fluid substitution procedure becomes debatable. Aiming at this problem, this paper attempts to explore the applicability of Gassmann’s theory in tight sandstones. Our focus is to investigate the sensitivity of dynamic shear modulus to fluid saturation and the possible mechanism. Ultrasonic velocity in dry and saturated tight sandstone samples was measured in the laboratory under an effective pressure within the range of 1-60 MPa. This study shows that the shear modulus of the water-saturated samples appears to either increase or decrease, and the soft porosity model (SPM) can be used to quantitatively estimate the variation of shear modulus. Under the condition of in situ pressure, samples dominated by secondary pores and microcracks are prone to show shear strengthening with saturation, which is possibly attributed to the local flow dispersion. Samples that mainly have primary pores are more likely to show shear weakening with saturation, which can be explained by the surface energy mechanism. We also find good correlation between changes in shear modulus and inaccurate Gassmann-predicted saturated velocity. Therefore, understanding the variation of shear modulus is helpful to improving the applicability of Gassmann’s theory in tight sandstones.
Coupling brane fields to bulk supergravity
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Parameswaran, Susha L. [Uppsala Univ. (Sweden). Theoretical Physics; Schmidt, Jonas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2010-12-15
In this note we present a simple, general prescription for coupling brane localized fields to bulk supergravity. We illustrate the procedure by considering 6D N=2 bulk supergravity on a 2D orbifold, with brane fields localized at the fixed points. The resulting action enjoys the full 6D N=2 symmetries in the bulk, and those of 4D N=1 supergravity at the brane positions. (orig.)
Influence of Bulk PDMS Network Properties on Water Wettability
Melillo, Matthew; Walker, Edwin; Klein, Zoe; Efimenko, Kirill; Genzer, Jan
Poly(dimethylsiloxane) (PDMS) is one of the most common elastomers, with applications ranging from sealants and marine antifouling coatings to absorbents for water treatment. Fundamental understanding of how liquids spread on the surface of and absorb into PDMS networks is of critical importance for the design and use of another application - medical devices. We have systematically studied the effects of polymer molecular weight, loading of tetra-functional crosslinker, and end-group chemical functionality on the mechanical and surface properties of end-linked PDMS networks. Wettability was investigated through the sessile drop technique, wherein a DI water droplet was placed on the bulk network surface and droplet volume, shape, surface area, and contact angle were monitored as a function of time. Various silicone substrates ranging from incredibly soft and flexible materials (E' 50 kPa) to highly rigid networks (E' 5 MPa) were tested. The dynamic behavior of the droplet on the surfaces demonstrated equilibration times between the droplet and surface on the order of 5 minutes. Similar trends were observed for the commercial PDMS material, Sylgard-184. Our results have provided new evidence for the strong influence that substrate modulus and molecular network structure have on the wettability of PDMS elastomers. These findings will aid in the design and implementation of efficient, accurate, and safe PDMS-based medical devices and microfluidic materials that involve aqueous media.
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Xie, Kelvin Y. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronics Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Wang, Yanbo, E-mail: yanbo.wang@sydney.edu.au [School of Aerospace, Mechanical and Mechatronics Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Zhao, Yonghao [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chang, Li; Wang, Guocheng; Chen, Zibin; Cao, Yang [School of Aerospace, Mechanical and Mechatronics Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Liao, Xiaozhou, E-mail: xiaozhou.liao@sydney.edu.au [School of Aerospace, Mechanical and Mechatronics Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Lavernia, Enrique J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Valiev, Ruslan Z. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, K. Marksa 12, Ufa 450000 (Russian Federation); Sarrafpour, Babak; Zoellner, Hans [The Cellular and Molecular Pathology Research Unit, Department of Oral Pathology and Oral Medicine, Faculty of Dentistry, The University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, NSW 2145 (Australia); Ringer, Simon P. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronics Engineering, The University of Sydney, Sydney, NSW 2006 (Australia)
2013-08-01
High strength, low Young's modulus and good biocompatibility are desirable but difficult to simultaneously achieve in metallic implant materials for load bearing applications, and these impose significant challenges in material design. Here we report that a nano-grained β-Ti alloy prepared by high-pressure torsion exhibits remarkable mechanical and biological properties. The hardness and modulus of the nano-grained Ti alloy were respectively 23% higher and 34% lower than those of its coarse-grained counterpart. Fibroblast cell attachment and proliferation were enhanced, demonstrating good in vitro biocompatibility of the nano-grained Ti alloy, consistent with demonstrated increased nano-roughness on the nano-grained Ti alloy. Results suggest that the nano-grained β-Ti alloy may have significant application as an implant material in dental and orthopedic applications. - Highlights: • A bulk nanocrystalline β-Ti alloy was produced by high-pressure torsion processing. • Excellent mechanical properties for biomedical implants were obtained. • Enhanced in vitro biocompatibility was also demonstrated.
Influence of grain size distribution on dynamic shear modulus of sands
Dyka, Ireneusz; Srokosz, Piotr E.; Bujko, Marcin
2017-11-01
The paper presents the results of laboratory tests, that verify the correlation between the grain-size characteristics of non-cohesive soils and the value of the dynamic shear modulus. The problem is a continuation of the research performed at the Institute of Soil Mechanics and Rock Mechanics in Karlsruhe, by T. Wichtmann and T. Triantafyllidis, who derived the extension of the applicability of the Hardin's equation describing the explicite dependence between the grain size distribution of sands and the values of dynamic shear modulus. For this purpose, piezo-ceramic bender elements generating elastic waves were used to investigate the mechanical properties of the specimens with artificially generated particle distribution. The obtained results confirmed the hypothesis that grain size distribution of non-cohesive soils has a significant influence on the dynamic shear modulus, but at the same time they have shown that obtaining unambiguous results from bender element tests is a difficult task in practical applications.
Sava, Mihaela; Hadǎr, Anton; Pǎrǎuşanu, Ioan; Petrescu, Horia-Alexandru; Baciu, Florin; Marinel, Stǎnescu Marius
2016-06-01
The influence of discontinuities is important for a correct determination of static and dynamic elastic characteristics of the material. In this paper we presented differences arising between the elastic modulus static and dynamic, laminated composite materials reinforced with carbon fiber, aramid and carbon-aramid, depending on the non-uniformity coefficient. For the study were determined static elastic modulus by carrying out traction tests and dynamic elastic modulus by determining the vibration frequency, on specimens of each type of material with and without discontinuities [1]. The elastic properties of composite materials resistance and can be influenced by various defects that arise from technological manufacturing process. This is important for the production of large series of parts of fiber-reinforced composite material, the fibers in the matrix distribution is not uniform. Studies on the mechanical behavior of composites with random distribution of fabrics are made in [2].
Guo, Y C; Wang, H; Wu, H P; Zhang, M Q
2015-12-21
Aimed to address the defects of the large mean square error (MSE), and the slow convergence speed in equalizing the multi-modulus signals of the constant modulus algorithm (CMA), a multi-modulus algorithm (MMA) based on global artificial fish swarm (GAFS) intelligent optimization of DNA encoding sequences (GAFS-DNA-MMA) was proposed. To improve the convergence rate and reduce the MSE, this proposed algorithm adopted an encoding method based on DNA nucleotide chains to provide a possible solution to the problem. Furthermore, the GAFS algorithm, with its fast convergence and global search ability, was used to find the best sequence. The real and imaginary parts of the initial optimal weight vector of MMA were obtained through DNA coding of the best sequence. The simulation results show that the proposed algorithm has a faster convergence speed and smaller MSE in comparison with the CMA, the MMA, and the AFS-DNA-MMA.
Studies on resilient modulus value from cyclic loading tests for cohesive soil
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Sas Wojciech
2017-06-01
Full Text Available In this article the cyclic CBR test as a reference method in determination of resilient modulus (Mr is confronted with results of cyclic triaxial and unconfined uniaxial cyclic test. The main idea of conducted experiments is establish relationship between cyclic loading tests in testing of natural subsoil and road materials. The article shows results of investigation on cohesive soil, namely sandy silty clay, commonly problematic soil in Poland. The results of repeated loading triaxial test resilient modulus were displayed in order to compare them with cyclic CBR test results by using the Mr–Ө model. Some empirical correlation between factors obtained from triaxial test or uniaxial unconfined cyclic test and cyclic CBR test was introduced here. The behavior of resilient modulus was also examined in this paper.
3-D FDTD simulation of shear waves for evaluation of complex modulus imaging.
Orescanin, Marko; Wang, Yue; Insana, Michael
2011-02-01
The Navier equation describing shear wave propagation in 3-D viscoelastic media is solved numerically with a finite differences time domain (FDTD) method. Solutions are formed in terms of transverse scatterer velocity waves and then verified via comparison to measured wave fields in heterogeneous hydrogel phantoms. The numerical algorithm is used as a tool to study the effects on complex shear modulus estimation from wave propagation in heterogeneous viscoelastic media. We used an algebraic Helmholtz inversion (AHI) technique to solve for the complex shear modulus from simulated and experimental velocity data acquired in 2-D and 3-D. Although 3-D velocity estimates are required in general, there are object geometries for which 2-D inversions provide accurate estimations of the material properties. Through simulations and experiments, we explored artifacts generated in elastic and dynamic-viscous shear modulus images related to the shear wavelength and average viscosity.
Farsi, A.; Pullen, A. D.; Latham, J. P.; Bowen, J.; Carlsson, M.; Stitt, E. H.; Marigo, M.
2017-04-01
New engineered materials have critical applications in different fields in medicine, engineering and technology but their enhanced mechanical performances are significantly affected by the microstructural design and the sintering process used in their manufacture. This work introduces (i) a methodology for the calculation of the full deflection profile from video recordings of bending tests, (ii) an optimisation algorithm for the characterisation of Young’s modulus, (iii) a quantification of the effects of optical distortions and (iv) a comparison with other standard tests. The results presented in this paper show the capabilities of this procedure to evaluate the Young’s modulus of highly stiff materials with greater accuracy than previously possible with bending tests, by employing all the available information from the video recording of the tests. This methodology extends to this class of materials the possibility to evaluate both the elastic modulus and the tensile strength with a single mechanical test, without the need for other experimental tools.
Yegingil, Hakki; Shih, Wan Y; Shih, Wei-Heng
2007-11-01
We have experimentally investigated the depth sensitivity limit of a piezoelectric cantilever tissue elastic modulus sensor and simultaneously determined the elastic modulus and the depth of a tumor directly. Using model tissues consisting of bottom-supported modeling clay inclusions of various depths in a gelatin matrix, we empirically determined that the depth sensitivity limit of a piezoelectric cantilever sensor was twice the linear dimension of the indentation area (or the cantilever width). Knowing the depth sensitivity limit of the individual cantilever sensor as input and treating a model tissue that has the gelatin matrix on top and the modeling clay inclusion at the bottom as two springs in series, we showed that the elastic moduli and depths of the hard inclusions could be simultaneously determined with the elastic modulus profiles measured by two cantilevers with different widths as input.
Axial shear modulus of a fiber-reinforced composite with random fiber cross-sections
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S. K. Bose
1982-01-01
Full Text Available A study is made of the effective axial shear modulus of a fiber reinforced material with random fiber cross-sections so that the micromechanics is governed by stochastic differential equations. A coarse-graining procedure is adopted to investigate the macroscopic behavior of the material. This analysis leads to the formula for the effective axial shear modulus μ∗=μ1/{1−2c(μ2−μ1/(μ2+μ1},where μ1 and μ2 are the shear modulus of the matrix and fibers respectively and c is the concentration of the fibers less that 0.5. For c>0.5, the fiber and matrix moduli are to be interchanged and c is to be replaced by 1−c. The results of this study are compared with those of the theory of fibre reinforced materials. Finally, a numerical example is presented with graphical representation.
Khatam, Hamed; Ravi-Chandar, K.
2013-01-01
A nonlinear optimization procedure is established to determine the elastic modulus of slender, soft materials using beams with unknown initial curvature in the presence of large rotations. Specifically, the deflection of clamped-free beams under self-weight – measured at different orientations with respect to gravity – is used to determine the modulus of elasticity and the intrinsic curvature in the unloaded state. The approach is validated with experiments on a number of different materials – steel, polyetherimide, rubber and pig skin. Since the loading is limited to self-weight, the strain levels attained in these tests are small enough to assume a linear elastic material behavior. This nondestructive methodology is also applicable to engineered tissues and extremely delicate materials in order to obtain a quick estimate of the material’s elastic modulus. PMID:24159244
A Regev-Type Fully Homomorphic Encryption Scheme Using Modulus Switching
Chen, Zhigang; Wang, Jian; Song, Xinxia
2014-01-01
A critical challenge in a fully homomorphic encryption (FHE) scheme is to manage noise. Modulus switching technique is currently the most efficient noise management technique. When using the modulus switching technique to design and implement a FHE scheme, how to choose concrete parameters is an important step, but to our best knowledge, this step has drawn very little attention to the existing FHE researches in the literature. The contributions of this paper are twofold. On one hand, we propose a function of the lower bound of dimension value in the switching techniques depending on the LWE specific security levels. On the other hand, as a case study, we modify the Brakerski FHE scheme (in Crypto 2012) by using the modulus switching technique. We recommend concrete parameter values of our proposed scheme and provide security analysis. Our result shows that the modified FHE scheme is more efficient than the original Brakerski scheme in the same security level. PMID:25093212
Sumi, C.
Previously, we developed three displacement vector measurement methods, i.e., the multidimensional cross-spectrum phase gradient method (MCSPGM), the multidimensional autocorrelation method (MAM), and the multidimensional Doppler method (MDM). To increase the accuracies and stabilities of lateral and elevational displacement measurements, we also developed spatially variant, displacement component-dependent regularization. In particular, the regularization of only the lateral/elevational displacements is advantageous for the lateral unmodulated case. The demonstrated measurements of the displacement vector distributions in experiments using an inhomogeneous shear modulus agar phantom confirm that displacement-component-dependent regularization enables more stable shear modulus reconstruction. In this report, we also review our developed lateral modulation methods that use Parabolic functions, Hanning windows, and Gaussian functions in the apodization function and the optimized apodization function that realizes the designed point spread function (PSF). The modulations significantly increase the accuracy of the strain tensor measurement and shear modulus reconstruction (demonstrated using an agar phantom).
On the Tapping Mode Measurement for Young’s Modulus of Nanocrystalline Metal Coatings
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H. S. Tanvir Ahmed
2013-01-01
Full Text Available Young’s modulus of nanocrystalline metal coatings is measured using the oscillating, that is, tapping, mode of a cantilever with a diamond tip. The resonant frequency of the cantilever changes when the diamond tip comes in contact with a sample surface. A Hertz-contact-based model is further developed using higher-order terms in a Taylor series expansion to determine a relationship between the reduced elastic modulus and the shift in the resonant frequency of the cantilever during elastic contact between the diamond tip and sample surface. The tapping mode technique can be used to accurately determine Young’s modulus that corresponds with the crystalline orientation of the sample surface as demonstrated for nanocrystalline nickel, vanadium, and tantalum coatings.
Directory of Open Access Journals (Sweden)
Ming Liang
2016-07-01
Full Text Available High modulus bitumens modified by polystyrene-block-polybutadiene-block-polystyrene (SBS with different molecular structure were investigated on dynamic shear rheometer and fluorescence microscopy to evaluate viscoelastic properties and morphology of binders. The results shows that storage modulus (G’ is obviously less than loss modulus (G”, which means viscous behaviour of bitumen is dominant, and anti-rutting factor (G* ⁄ sin δ is markedly enhanced by star SBS than by linear SBS. The morphology indicated that star SBS improved the softening point more obviously, tending to form a cross-linked network in bitumen. As for linear SBS, it is dispersed in bitumen in the form of globules and enhances the ductility of binder.
A Model of Temperature-Dependent Young's Modulus for Ultrahigh Temperature Ceramics
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Weiguo Li
2011-01-01
Full Text Available Based on the different sensitivities of material properties to temperature between ultrahigh temperature ceramics (UHTCs and traditional ceramics, the original empirical formula of temperature-dependent Young's modulus of ceramic materials is unable to describe the temperature dependence of Young's modulus of UHTCs which are used as thermal protection materials. In this paper, a characterization applied to Young's modulus of UHTC materials under high temperature which is revised from the original empirical formula is established. The applicable temperature range of the characterization extends to the higher temperature zone. This study will provide a basis for the characterization for strength and fracture toughness of UHTC materials and provide theoretical bases and technical reserves for the UHTC materials' design and application in the field of spacecraft.
Shear Modulus of the Lower Leg Muscles in Patients with Medial Tibial Stress Syndrome.
Akiyama, Kei; Akagi, Ryota; Hirayama, Kuniaki; Hirose, Norikazu; Takahashi, Hideyuki; Fukubayshi, Toru
2016-08-01
This study aimed to investigate the in vivo kinematics of shear modulus of the lower leg muscles in patients with medial tibial stress syndrome (MTSS). The study population included 46 limbs with MTSS and 40 healthy limbs. The shear modulus of the medial head of the gastrocnemius, lateral head of the gastrocnemius, soleus, peroneus longus and tibialis anterior muscles were measured using shear wave ultrasound elastography. As a result, the shear modulus of the lower leg muscles was significantly greater in patients with MTSS than in healthy patients (p risk factors of MTSS. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Sinha Roy, Abhijit; Rocha, Karol M; Randleman, J Bradley; Stulting, R Doyle; Dupps, William J
2013-08-01
Corneal collagen crosslinking with riboflavin photosensitization and ultraviolet irradiation is a novel approach to limiting the progression of keratoconus in patients by increasing the elastic modulus of the degenerate cornea. Beneficial reductions in corneal steepness and aberrations after crosslinking also frequently occur. In a previous study, we described a computational modeling approach to simulating topographic progression in keratoconus and regression of disease with corneal collagen crosslinking. In the current study, this model has been expanded and applied to the inverse problem of estimating longitudinal time-dependent changes in the corneal elastic modulus after crosslinking using in vivo measurements from 16 human eyes. Topography measured before crosslinking was used to construct a patient-specific finite element model with assumed hyperelastic properties. Then the properties of the cornea were altered using an inverse optimization method to minimize the difference between the model-predicted and in vivo corneal shape after crosslinking. Effects of assumptions regarding sclera-to-cornea elastic modulus ratio and spatial attenuation of treatment effect due to ultraviolet beam characteristics on the predicted change in elastic modulus were also investigated. Corneal property changes computed by inverse finite element analysis provided excellent geometric agreement with clinical topography measurements in patient eyes post-crosslinking. Over all post-treatment time points, the estimated increase in corneal elastic modulus was 110.8 ± 48.1%, and slightly less stiffening was required to produce the same amount of corneal topographic regression of disease when the sclera-to-cornea modulus ratio was increased. Including the effect of beam attenuation resulted in greater estimates of stiffening in the anterior cornea. Corneal shape responses to crosslinking varied considerably and emphasize the importance of a patient-specific approach. Copyright © 2013
Comparison of mechanical and ultrasound elastic modulus of ovine tibial cortical bone.
Grant, Caroline A; Wilson, Lance J; Langton, Christian; Epari, Devakar
2014-07-01
Finite element models of bones can be created by deriving geometry from an X-ray CT scan. Material properties such as the elastic modulus can then be applied using either a single or set of homogeneous values, or individual elements can have local values mapped onto them. Values for the elastic modulus can be derived from the CT density values using an elasticity versus density relationship. Many elasticity-density relationships have been reported in the literature for human bone. However, while ovine in vivo models are common in orthopaedic research, no work has been done to date on creating FE models of ovine bones. To create these models and apply relevant material properties, an ovine elasticity-density relationship needs to be determined. Using fresh frozen ovine tibias the apparent density of regions of interest was determined from a clinical CT scan. The bones were the sectioned into cuboid samples of cortical bone from the regions of interest. Ultrasound was used to determine the elastic modulus in each of three directions - longitudinally, radially and tangentially. Samples then underwent traditional compression testing in each direction. The relationships between apparent density and both ultrasound, and compression modulus in each direction were determined. Ultrasound testing was found to be a highly repeatable non-destructive method of calculating the elastic modulus, particularly suited to samples of this size. The elasticity-density relationships determined in the longitudinal direction were very similar between the compression and ultrasound data over the density range examined. A clear difference was seen in the elastic modulus between the longitudinal and transverse directions of the bone samples, and a transverse elasticity-density relationship is also reported. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.
Magnetic-field-dependent shear modulus of a magnetorheological elastomer based on natural rubber
Yang, In-Hyung; Yoon, Ji-Hyun; Jeong, Jae-Eun; Jeong, Un-Chang; Kim, Jin-Su; Chung, Kyung Ho; Oh, Jae-Eung
2013-01-01
A magnetorheological elastomer (MRE) is a smart material that has a reversible and variable modulus in a magnetic field. Natural rubber, which has better physical properties than silicone matrices, was used as a matrix in the fabrication of the MREs used in this study. Carbonyl iron powder (CIP), which has a rapid magnetic reaction, was selected as a magnetic material to generate the magnetic-field-dependent modulus in the MREs. The MRE specimens were cured in an anisotropic mold, which could be used to induce a uniaxial magnetic field via permanent magnets, to control the orientation of the CIP, and the shear modulus of the MREs was evaluated under a magnetic field induced by using a magnetic flux generator (MFG). Because the use of a conventional evaluation system to determine the magnetic-field-dependent shear modulus of the MREs was difficult, an evaluation system based on single degree-of-freedom vibration and electromagnetics that included an MFG, which is a device that generates a magnetic field via a variable induced current, was designed. An electromagnetic finite element method (FEM) analysis and design of experiments (DoE) techniques were employed to optimize the magnetic flux density generated by the MFG. The optimized system was verified over the range to determine the magnetic flux density generated by the MFG in order to use a magnetic circuit analysis to identify the existence of magnetic saturation. A variation in the shear modulus was observed with increasing CIP volume fraction and induced current. The experimental results revealed that the maximum variation in the shear modulus was 76.3% for 40 vol% CIP at an induced current of 4 A. With these results, the appropriate CIP volume fraction, induced current, and design procedure of the MFG can be proposed as guidelines for applications of MREs based on natural rubber.
Labonte, David; Lenz, Anne-Kristin; Oyen, Michelle L
2017-07-15
The remarkable mechanical performance of biological materials is based on intricate structure-function relationships. Nanoindentation has become the primary tool for characterising biological materials, as it allows to relate structural changes to variations in mechanical properties on small scales. However, the respective theoretical background and associated interpretation of the parameters measured via indentation derives largely from research on 'traditional' engineering materials such as metals or ceramics. Here, we discuss the functional relevance of indentation hardness in biological materials by presenting a meta-analysis of its relationship with indentation modulus. Across seven orders of magnitude, indentation hardness was directly proportional to indentation modulus. Using a lumped parameter model to deconvolute indentation hardness into components arising from reversible and irreversible deformation, we establish criteria which allow to interpret differences in indentation hardness across or within biological materials. The ratio between hardness and modulus arises as a key parameter, which is related to the ratio between irreversible and reversible deformation during indentation, the material's yield strength, and the resistance to irreversible deformation, a material property which represents the energy required to create a unit volume of purely irreversible deformation. Indentation hardness generally increases upon material dehydration, however to a larger extent than expected from accompanying changes in indentation modulus, indicating that water acts as a 'plasticiser'. A detailed discussion of the role of indentation hardness, modulus and toughness in damage control during sharp or blunt indentation yields comprehensive guidelines for a performance-based ranking of biological materials, and suggests that quasi-plastic deformation is a frequent yet poorly understood damage mode, highlighting an important area of future research. Instrumented
Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys
Energy Technology Data Exchange (ETDEWEB)
Thompson, Zachary T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-10-01
Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.
Modelling of the Elasticity Modulus for Rock Using Genetic Expression Programming
Directory of Open Access Journals (Sweden)
Umit Atici
2016-01-01
Full Text Available In rock engineering projects, statically determined parameters are more reflective of actual load conditions than dynamic parameters. This study reports a new and efficient approach to the formulation of the static modulus of elasticity Es applying gene expression programming (GEP with nondestructive testing (NDT methods. The results obtained using GEP are compared with the results of multivariable linear regression analysis (MRA, univariate nonlinear regression analysis (URA, and the dynamic elasticity modulus (Ed. The GEP model was found to produce the most accurate calculation of Es. The proposed approach is a simple, nondestructive, and practical way to determine Es for anisotropic and heterogeneous rocks.
Back-analysing rock mass modulus from monitoring data of two tunnels in Sydney, Australia
Directory of Open Access Journals (Sweden)
Robert Bertuzzi
2017-10-01
Full Text Available This paper presents two case studies where the rock mass modulus and in situ stress are estimated from the monitoring data obtained during the construction of underground excavations in Sydney, Australia. The case studies comprise the widening of existing twin road tunnels within Hawkesbury sandstone and the excavation of a large cavern within Ashfield shale. While back-analysis from detailed systematic monitoring has been previously published, this paper presents a relatively simple methodology to derive rock mass modulus and in situ stress from the relatively simple displacement data routinely recorded during tunnelling.
Directory of Open Access Journals (Sweden)
DAOUI Abdelhakim
2018-01-01
Full Text Available In this paper, we present a method for the determination of the elasticity modulus in the vibratory domain of materials. This approach is based on research and interpretation of the spectrum of natural frequencies resulting from natural vibrations based on the theory of elastic beams. The tests consist of classical tests of longitudinal vibrations of natural composite beams (Aleppo pine wood, long enough to observe some natural frequencies. This identification method showed a good correlation between the theoretical and experimental values, notably the evaluation of the modal parameter for the case of the resonant frequencies and the identification of the modulus of elasticity of the materials used.
Elastic modulus of a colloidal suspension of rigid spheres at rest
Pasol, Laurentiu; Chateau, Xavier
2008-06-01
By modeling a colloidal suspension at rest as a solid, a new expression for the linear elastic modulus is obtained. This estimate is valid for a yield stress colloidal suspension submitted to a small strain. Interestingly, it is also possible to construct an hypothesis allowing one to recover the high-frequency modulus classically found by means of a classical 'fluid approach'. However, in most of the situations, the moduli obtained by the two approaches are different. To cite this article: L. Pasol, X. Chateau, C. R. Mecanique 336 (2008).
A Research on Low Modulus Distributed Fiber Optical Sensor for Pavement Material Strain Monitoring.
Meng, Lingjian; Wang, Linbing; Hou, Yue; Yan, Guannan
2017-10-19
The accumulated irreversible deformation in pavement under repeated vehicle loadings will cause fatigue failure of asphalt concrete. It is necessary to monitor the mechanical response of pavement under load by using sensors. Previous studies have limitations in modulus accommodation between the sensor and asphalt pavement, and it is difficult to achieve the distributed monitoring goal. To solve these problems, a new type of low modulus distributed optical fiber sensor (DOFS) for asphalt pavement strain monitoring is fabricated. Laboratory experiments have proved the applicability and accuracy of the newly-designed sensor. This paper presents the results of the development.
A quantitative comparison of modulus images obtained using nanoindentation with strain elastograms.
Srinivasan, S; Krouskop, T; Ophir, J
2004-07-01
Tissue stiffness is generally known to be associated with pathologic changes. Ultrasound (US) elastography, on the other hand, is capable of imaging tissue strain, which may or may not be well-correlated with tissue stiffness. Hence, a quantitative comparison between the elastographic tissue strain images and the corresponding tissue modulus images needed to be performed to evaluate the usefulness of elastography in imaging tissue stiffnesss properties. Simulations were performed to demonstrate and quantify the similarities between modulus images and strain elastograms. This was followed by comparing nanoindenter-based modulus images with strain elastograms of thin slices of tissue-mimicking phantoms. Finally, some beef slices, canine prostates, ovine kidneys and breast cancers grown in mice were used to demonstrate the qualitative correspondence between modulus images and strain elastograms. The simulations and the experiments indicated that it is feasible to perform quantitative comparisons between strain images (using elastography) and modulus images on certain tissue structures and geometries. A good quantitative correspondence (correlation values of greater than 0.8) between structures in the modulus and strain images could be obtained at scales equal to or larger than 20 Qlambda (where Q is the quality factor defined as the ratio of the center frequency over the band width and lambda is the wavelength of the US system) modulus contrasts larger than 5, applied strains between 0.5% and 3% and window lengths for computing strain elastograms between 3 Qlambda and 5 Qlambda. The gelatin-phantom experiments showed lower values of correlation (values around 0.5) than with theory and simulations. The decrease in correlation was attributed to the presence of measurement noise in both strain elastography and modulus imaging, an increase of dimensionality of the problem (from 2-D to 3-D), local anisotropy, heterogeneity and nonstationarity. Experiments on real tissue
27 CFR 20.191 - Bulk articles.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of this...
Veni Takarini; Nina Djustiana; Renny Febrida
2012-01-01
Modulus of elasticity is one of the mechanical properties of composite resins affects the resistance to deformation, the strength of bonding with tooth structure and wear resistance. Modulus of elasticity is determined by the volume fraction of filler particles as the inorganic phase composite resin. This literature study aims to evaluate the size, shape and type of filler particles that affect the modulus of elasticity for composite resin. In a constant volume fraction, the large...
Young's modulus and residual stress of GeSbTe phase-change thin films
Nazeer, H.; Bhaskaran, Harish; Woldering, L.A.; Abelmann, Leon
2015-01-01
The mechanical properties of phase change materials alter when the phase is transformed. In this paper, we report on experiments that determine the change in crucial parameters such as Young's modulus and residual stress for two of the most widely employed compositions of phase change films,
Elastic modulus affects the growth and differentiation of neural stem cells
Directory of Open Access Journals (Sweden)
Xian-feng Jiang
2015-01-01
Full Text Available It remains poorly understood if carrier hardness, elastic modulus, and contact area affect neural stem cell growth and differentiation. Tensile tests show that the elastic moduli of Tiansu and SMI silicone membranes are lower than that of an ordinary dish, while the elastic modulus of SMI silicone membrane is lower than that of Tiansu silicone membrane. Neural stem cells from the cerebral cortex of embryonic day 16 Sprague-Dawley rats were seeded onto ordinary dishes as well as Tiansu silicone membrane and SMI silicone membrane. Light microscopy showed that neural stem cells on all three carriers show improved adherence. After 7 days of differentiation, neuron specific enolase, glial fibrillary acidic protein, and myelin basic protein expression was detected by immunofluorescence. Moreover, flow cytometry revealed a higher rate of neural stem cell differentiation into astrocytes on Tiansu and SMI silicone membranes than on the ordinary dish, which was also higher on the SMI than the Tiansu silicone membrane. These findings confirm that all three cell carrier types have good biocompatibility, while SMI and Tiansu silicone membranes exhibit good mechanical homogenization. Thus, elastic modulus affects neural stem cell differentiation into various nerve cells. Within a certain range, a smaller elastic modulus results in a more obvious trend of cell differentiation into astrocytes.
Prediction of the elastic modulus of wood flour/kenaf fibre/polypropylene hybrid composites
Jamal Mirbagheri; Mehdi Tajvidi; Ismaeil Ghasemi; John C. Hermanson
2007-01-01
The prediction of the elastic modulus of short natural fibre hybrid composites has been investigated by using the properties of the pure composites through the rule of hybrid mixtures (RoHM) equation. In this equation, a hybrid natural fibre composite assumed as a system consisting of two separate single systems, namely particle/polymer and short-fibre/polymer systems...
Relations between the modulus of elasticity of binary alloys and their structure
Koster, Werner; Rauscher, Walter
1951-01-01
A comprehensive survey of the elastic modulus of binary alloys as a function of the concentration is presented. Alloys that form continuous solid solutions, limited solid solutions, eutectic alloys, and alloys with intermetallic phases are investigated. Systems having the most important structures have been examined to obtain criteria for the relation between lattice structure, type of binding, and elastic behavior.
Effect of LED light-curing time for the adhesive resin on the modulus of elasticity.
Senawongse, Pisol; Harnirattisai, Choltacha; Otsuki, Masayuki; Tagami, Junji
2007-06-01
To evaluate the elastic modulus of successive layers where an adhesive resin was cured by different light-curing times. Eighty dentin discs which were 2 mm thick were prepared from 40 sound third molars. The dentin discs were further divided into four groups and bonded with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and 20s. Bonded specimens were restored with a microhybrid resin composite. Specimens were cut perpendicular to the resin dentin interface, embedded in epoxy resin, and polished. Polished specimens were evaluated for the elastic modulus at the layer of dentin, hybrid layer, adhesive resin, and resin composite at 24 hours after preparation. Light-curing times influenced the elastic modulus of hybrid layer and adhesive resin. The significant differences of elastic modulus among successive layers were found. The results suggested that extension of light-curing times of adhesive resin from 5 to 20 seconds increased the mechanical properties of the resin dentin interface.
Flexural strength and modulus of elasticity of different types of resin-based composites.
Rodrigues Junior, Sinval Adalberto; Zanchi, Cesar Henrique; Carvalho, Rodrigo Varella de; Demarco, Flávio Fernando
2007-01-01
The aim of the study was to test whether the filler composition of resin composites influences their flexural strength and modulus of elasticity. Flexural strength and modulus of elasticity were obtained through a three-point bending test. Twelve bar shaped specimens of 5 commercially available composites--Supreme (3M/ESPE), a universal nanofilled composite; Esthet-X (Dentsply), Z-250 (3M/ESPE), Charisma (Heraeus Kulzer), universal hybrid composites; and Helio Fill (Vigodent), a microfine composite--were confectioned according to the ISO 4049/2000 specifications. The test was performed after a 7-days storage time using a universal test machine with a crosshead speed of 1 mm/min. The filler weight content was determined by the ashing technique. The data obtained on the mechanical properties were submitted to ANOVA and Tukey test (p modulus of elasticity results were observed among the universal hybrid composites. The nanofilled composite presented intermediary results. Within the limitations of this in vitro study, it could be concluded that the filler content significantly interfered in the flexural strength and modulus of elasticity of the composites tested.
Elasticity modulus of rabbit middle ear ossicles determined by a novel micro-indentation technique.
Soons, Joris A M; Aernouts, Jef; Dirckx, Joris J J
2010-05-01
For the purpose of creating a finite element model of the middle ear, the ossicles can be modelled as rigid bodies or as linear elastic materials. The general elasticity parameters used are usually measured on larger bones like the femur. In order to obtain a highly realistic model, the actual elastic modulus (Young's modulus) of the ossicles themselves is needed. We developed a novel 2-needle indentation method of determining the Young's modulus of small samples based on Sneddon's solution. We introduce the second needle in such a way that small specimens can be clamped between the two needles and a symmetry plane is obtained, so that geometry-dependent sample deformations are avoided. A finite element calculated correction factor is used to compensate for the small thickness of the samples. The system was tested on several materials with known parameters in order to validate the technique, and was then used to determine the elasticity parameters of incus and malleus in rabbit. No significant differences between measurement locations were found, and we found an average Young's modulus of 16+/-3 GPa. Copyright (c) 2009 Elsevier B.V. All rights reserved.
Evaluation the Effects of Some Relevant Parameters on Elastic Modulus of Pumpkin Seed and Its Kernel
Abbaspour-Fard, Mohammad Hossein; Khodabakhshian, Rasool; Emadi, Bagher; Sadrnia, Hasan
2012-01-01
The elastic modulus of two varieties of Iranian pumpkin seed and its kernel (namely, Zaria and Gaboor) were evaluated as a function of size (large, medium, and small), loading rate (2, 5, 8, and 10 mm/min), and moisture content (4, 7.8, 14, and 20% d.b) under quasistatic compression loading. The results showed that elastic modulus of pumpkin seed and its kernel decreased with increasing moisture content and also increasing loading rate, for the varieties under study. The average modulus of elasticity of pumpkin seed from 68.86 to 46.65 Mpa and from 97.14 to 74.93 Mpa was obtained for moisture levels ranging from 4 to 20%, for Zaria and Gaboor varieties, respectively. The elastic modulus of pumpkin seed decreased from 73.55 to 43.04 Mpa and from 101.83 to 71.32 Mpa with increasing loading rate from 2 to 10 mm/min for Zaria and Gaboor varieties, respectively. PMID:22481937
Strain-rate Dependence of Elastic Modulus Reveals Silver Nanoparticle Induced Cytotoxicity
Caporizzo, Matthew Alexander; Roco, Charles M.; Ferrer, Maria Carme Coll; Grady, Martha E.; Parrish, Emmabeth; Eckmann, David M.; Composto, Russell John
2015-01-01
Force-displacement measurements are taken at different rates with an atomic force microscope to assess the correlation between cell health and cell viscoelasticity in THP-1 cells that have been treated with a novel drug carrier. A variable indentation-rate viscoelastic analysis, VIVA, is employed to identify the relaxation time of the cells that are known to exhibit a frequency dependent stiffness. The VIVA agrees with a fluorescent viability assay. This indicates that dextran-lysozyme drug carriers are biocompatible and deliver concentrated toxic material (rhodamine or silver nanoparticles) to the cytoplasm of THP-1 cells. By modelling the frequency dependence of the elastic modulus, the VIVA provides three metrics of cytoplasmic viscoelasticity: a low frequency modulus, a high frequency modulus and viscosity. The signature of cytotoxicity by rhodamine or silver exposure is a frequency independent twofold increase in the elastic modulus and cytoplasmic viscosity, while the cytoskeletal relaxation time remains unchanged. This is consistent with the known toxic mechanism of silver nanoparticles, where metabolic stress causes an increase in the rigidity of the cytoplasm. A variable indentation-rate viscoelastic analysis is presented as a straightforward method to promote the self-consistent comparison between cells. This is paramount to the development of early diagnosis and treatment of disease. PMID:26834855
Hatipoglu, Gokhan; Liu, Yang; Zhao, Ran; Yoonessi, Mitra; Tigelaar, Dean M.; Tadigadapa, Srinivas; Zhang, Q. M.
2012-05-01
A high modulus, sulfonated ionomer synthesized from 4,6-bis(4-hydroxyphenyl)-N,N-diphenyl-1,3,5-triazin-2-amine and 4,4‧-biphenol with bis(4-fluorophenyl)sulfone (DPA-PS:BP) is investigated for ionic polymer actuators. The uniqueness of DPA-PS:BP is that it can have a high ionic liquid (IL) uptake and consequently generates a high intrinsic strain response, which is >1.1% under 1.6 V while maintaining a high elastic modulus (i.e. 600 MPa for 65 vol% IL uptake). Moreover, such a high modulus of the active ionomer, originating from the highly aromatic backbone and side-chain-free structure, allows for the fabrication of free-standing thin film micro-actuators (down to 5 µm thickness) via the solution cast method and focused-ion-beam milling, which exhibits a much higher bending actuation, i.e. 43 µm tip displacement and 180 kPa blocking stress for a 200 µm long and 5 µm thick cantilever actuator, compared with the ionic actuators based on traditional ionomers such as Nafion, which has a much lower elastic modulus (50 MPa) and actuation strain.
A summary of modulus of elasticity and knot size surveys for laminating grades of lumber
R. W. Wolfe; R. C. Moody
1981-01-01
A summary of modulus of elasticity (MOE) and knot data is presented for grades of lumber commonly used to manufacture glued-laminated (glulam) timber by the laminating Industry. Tabulated values represent 30 different studies covering a time span of over 16 years. Statistical estimates of average and near-maximum knot sizes as well as mean and coefficient of variation...
Elastoplastic properties of a low-modulus titanium-based β alloy
Betekhtin, V. I.; Kolobov, Yu. R.; Golosova, O. A.; Kardashev, B. K.; Kadomtsev, A. G.; Narykova, M. V.; Ivanov, M. B.; Vershinina, T. N.
2013-10-01
The elastoplastic properties (elastic modulus, amplitude-independent damping ratio, microplastic flow stress) of a Ti-26Nb-7Mo-12Zr titanium β alloy are determined using an acoustic resonance method. The effect of the strain during thermomechanical treatment on the structural features of the micro-crystalline alloy and, hence, its elastoplastic properties is analyzed.
Directory of Open Access Journals (Sweden)
A Jafari Malekabadi
2016-04-01
Full Text Available Introduction: Poisson ratio and modulus of elasticity are two fundamental properties of elastic and viscoelastic solids that use in solving all contact problems, including the calculation of stress, the contact surfaces and elastic deformation (Mohsenin, 1986; Gentle and Halsall, 1982. There are many published literature on Poisson ratio and elasticity modulus of fruit and vegetables. Shitanda et al. (2002 calculated Poisson ratio of rice by considering Boussinesq’s theory. They showed that the Poisson ratio is greater for shorter varieties. In another study, researchers used the instrumented bending beam to measure the lateral expansion of red beans. They were considered Poisson ratio as the ratio of transverse strain to the longitudinal strain (regardless of the geometry of the sample and were calculated modulus of elasticity with Hertz theory for convex bodies (Kiani Deh Kiani et al., 2009. Cakir et al. (2002 was determined the Poisson ratio and elastic modulus of some onion varieties. They used a simple formula to determine the transverse strain that developed by Sitkei (1986 for prism-shaped rod, regardless of the geometry of the product. Reviewed scientific literature shows that these parameters have not been studied according to the geometric shape of onions and was not used by a more accurate method, such as image processing to determine these parameters. The objective of this study was to evaluate the mechanical properties of two varieties of onions. Poisson ratio was determined with image processing. Considering shape of the onions and deformation value, and using Hertz’s theory with Poisson ratio, modulus of elasticity was calculated. The effects of loading directions (polar or equatorial, deformation value (5, 10 and 15 mm, loading speed (15 or 25 mm min-1 and onion varieties (Red and Yellow on the modulus of elasticity and apparent Poisson’s ratio were examined. Materials and Methods: The onions harvested in autumn, 20 days
Stiffness modulus and creep properties of the coconut shell in an ...
African Journals Online (AJOL)
Coconut shell (CS) is an agricultural waste engineered into a road construction material. This study was conducted to evaluate the stiffness modulus and dynamic creep properties of the asphaltic concrete containing CS as an aggregate replacement. A mixture design incorporating the bitumen penetration grade 60/70 was ...
Short cellulosic fiber/starch acetate composites — micromechanical modeling of Young’s modulus
DEFF Research Database (Denmark)
Madsen, Bo; Joffe, Roberts; Peltola, Heidi
2011-01-01
This study is presented to predict the Young’s modulus of injection-molded short cellulosic fiber/plasticized starch acetate composites with variable fiber and plasticizer content. A modified rule of mixtures model is applied where the effect of porosity is included, and where the fiber weight...
The influence of resin flexural modulus on the magnitude of ceramic strengthening.
LENUS (Irish Health Repository)
Fleming, Garry J P
2012-07-01
The aim was to determine the magnitude of ceramic resin-strengthening with resin-based materials with varying flexural moduli using a regression technique to assess the theoretical strengthening at a \\'zero\\' resin-coating thickness. The hypothesis tested was that experimentally, increasing resin flexural modulus results in increased resin-strengthening observed at a theoretical \\'zero\\' resin-coating thickness.
Directory of Open Access Journals (Sweden)
Rachelle N Palchesko
Full Text Available Mechanics is an important component in the regulation of cell shape, proliferation, migration and differentiation during normal homeostasis and disease states. Biomaterials that match the elastic modulus of soft tissues have been effective for studying this cell mechanobiology, but improvements are needed in order to investigate a wider range of physicochemical properties in a controlled manner. We hypothesized that polydimethylsiloxane (PDMS blends could be used as the basis of a tunable system where the elastic modulus could be adjusted to match most types of soft tissue. To test this we formulated blends of two commercially available PDMS types, Sylgard 527 and Sylgard 184, which enabled us to fabricate substrates with an elastic modulus anywhere from 5 kPa up to 1.72 MPa. This is a three order-of-magnitude range of tunability, exceeding what is possible with other hydrogel and PDMS systems. Uniquely, the elastic modulus can be controlled independently of other materials properties including surface roughness, surface energy and the ability to functionalize the surface by protein adsorption and microcontact printing. For biological validation, PC12 (neuronal inducible-pheochromocytoma cell line and C2C12 (muscle cell line were used to demonstrate that these PDMS formulations support cell attachment and growth and that these substrates can be used to probe the mechanosensitivity of various cellular processes including neurite extension and muscle differentiation.
Measurement of Young’s modulus and damping of fibers at cryogenic temperatures
Rice, Brian; Quinzi, Joseph; Lund, Lance; Ulreich, Jeffrey; Shoup, Milton
2014-09-01
High-yield inertial confinement fusion targets are at cryogenic temperatures and must remain stable to within 10 μm during the implosion. Young’s modulus and damping properties of fibers used to mount cryogenic targets are needed to design stable targets, but these property values do not exist in literature. A novel experimental method that tracks how target vibrations respond to an impulse is used to quantitatively measure these properties from 295 to 20 K. Young’s modulus and the critical damping ratio are measured for NicalonTM ceramic grade [silicon carbide (SiC)], Zylon®HM {poly[p-phenlyne-2,6-benzobisoxazole] (PBO)}, M5 {dimidazo-pyridinylene [dihydroxy] phenylene (PIPD)}, and polyimide fibers. This method allows one to accurately measure the properties of interest for fiber diameters as small as 12 μm at ∼20 K. Significant changes are seen in Young’s modulus for the three polymeric fibers with respect to temperature; while Young’s modulus is relatively invariant to temperature for the ceramic fiber.
Determining shear modulus of thin wood composite materials using a cantilever beam vibration method
Cheng Guan; Houjiang Zhang; John F. Hunt; Haicheng Yan
2016-01-01
Shear modulus (G) of thin wood composite materials is one of several important indicators that characterizes mechanical properties. However, there is not an easy method to obtain this value. This study presents the use of a newly developed cantilever beam free vibration test apparatus to detect in-plane G of thin wood composite...
High modulus asphalt (EME) technology transfer to South Africa and Australia: shared experiences
CSIR Research Space (South Africa)
Denneman, E
2015-08-01
Full Text Available The paper describes experiences with the implementation of French enrobés à module élevé (EME) (high modulus asphalt) technology in South Africa and Australia. Tentative performance specifications for EME mixes were set in the two countries based...
Influence of disperse particles on the modulus of elasticity of polymer blends
Directory of Open Access Journals (Sweden)
Matseevich Tat’yana Anatol’evna
2014-09-01
Full Text Available The article considers various calculation methods for estimating modulus of elasticity depending on mixing formula. These dependencies can have different curvatures, showing that the modulus of elasticity of the blends can exceed the average values for different blends. The authors made a dynamic mechanical analysis of incompatible blends of polydimethylsiloxane and polyisoprene, the measured temperature dependence of modules accumulation and loss [3]. They detected two relaxation mechanisms, which can be suppressed by using computerization representing the diblock copolymers of the same components. The possibility of calculating elasticity modulus is presented for different situations: the dispersion of solid polymer in the viscoelastic matrix, dispersion of solid polymer 1 in solid polymer 2; dispersion of solid partially crystalline polymer in solid polymer 2. The dependence of the modulus of elasticity on molar and volume fraction have different forms, depending on Van der Waal component volume, the molecular weight of the recurring units, component density, domain volume, etc. The very form of the dependency is determined by the physical state (rubber elasticity polymer, crystalline polymer, solid amorphous polymer of the blend components.
Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers
DEFF Research Database (Denmark)
Colombi, Paolo; Bergese, Paolo; Bontempi, Elza
2013-01-01
A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C) with...
Detail of photo 7903109 stack of superconducting cables in the modulus measuring device
CERN PhotoLab
1979-01-01
The picture shows an assembly of insulated superconducting cables of the type used in the Po dipole magnet inserted in the elastic modulus measuring device (photos 7903547X and 7903169) in order to measures its mechanical properties under azimuthal compression. See also 7903547X, 7903169, 8307552X.
Directory of Open Access Journals (Sweden)
Chris L. de Korte
2013-03-01
Full Text Available Atherosclerotic plaque rupture can initiate stroke or myocardial infarction. Lipid-rich plaques with thin fibrous caps have a higher risk to rupture than fibrotic plaques. Elastic moduli differ for lipid-rich and fibrous tissue and can be reconstructed using tissue displacements estimated from intravascular ultrasound radiofrequency (RF data acquisitions. This study investigated if modulus reconstruction is possible for noninvasive RF acquisitions of vessels in transverse imaging planes using an iterative 2D cross-correlation based displacement estimation algorithm. Furthermore, since it is known that displacements can be improved by compounding of displacements estimated at various beam steering angles, we compared the performance of the modulus reconstruction with and without compounding. For the comparison, simulated and experimental RF data were generated of various vessel-mimicking phantoms. Reconstruction errors were less than 10%, which seems adequate for distinguishing lipid-rich from fibrous tissue. Compounding outperformed single-angle reconstruction: the interquartile range of the reconstructed moduli for the various homogeneous phantom layers was approximately two times smaller. Additionally, the estimated lateral displacements were a factor of 2–3 better matched to the displacements corresponding to the reconstructed modulus distribution. Thus, noninvasive elastic modulus reconstruction is possible for transverse vessel cross sections using this cross-correlation method and is more accurate with compounding.
Hansen, Hendrik H.G.; Richards, Michael S.; Doyley, Marvin M.; de Korte, Chris L.
2013-01-01
Atherosclerotic plaque rupture can initiate stroke or myocardial infarction. Lipid-rich plaques with thin fibrous caps have a higher risk to rupture than fibrotic plaques. Elastic moduli differ for lipid-rich and fibrous tissue and can be reconstructed using tissue displacements estimated from intravascular ultrasound radiofrequency (RF) data acquisitions. This study investigated if modulus reconstruction is possible for noninvasive RF acquisitions of vessels in transverse imaging planes using an iterative 2D cross-correlation based displacement estimation algorithm. Furthermore, since it is known that displacements can be improved by compounding of displacements estimated at various beam steering angles, we compared the performance of the modulus reconstruction with and without compounding. For the comparison, simulated and experimental RF data were generated of various vessel-mimicking phantoms. Reconstruction errors were less than 10%, which seems adequate for distinguishing lipid-rich from fibrous tissue. Compounding outperformed single-angle reconstruction: the interquartile range of the reconstructed moduli for the various homogeneous phantom layers was approximately two times smaller. Additionally, the estimated lateral displacements were a factor of 2–3 better matched to the displacements corresponding to the reconstructed modulus distribution. Thus, noninvasive elastic modulus reconstruction is possible for transverse vessel cross sections using this cross-correlation method and is more accurate with compounding. PMID:23478602
Xiawa Wu; Robert J. Moon; Ashlie Martini
2013-01-01
The elastic modulus of cellulose IÃ in the axial and transverse directions was obtained from atomistic simulations using both the standard uniform deformation approach and a complementary approach based on nanoscale indentation. This allowed comparisons between the methods and closer connectivity to experimental measurement techniques. A reactive...
Diameter effect on stress-wave evaluation of modulus of elasticity of logs
Xiping Wang; Robert J. Ross; Brian K. Brashaw; John Punches; John R. Erickson; John W. Forsman; Roy E. Pellerin
2004-01-01
Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of...
Contact modelling of human skin: what value to use for the modulus of elasticity?
van Kuilenburg, Julien; Masen, Marc Arthur; van der Heide, Emile
2012-01-01
In modelling and understanding the contact and friction behaviour of human skin, the elastic modulus of the skin is an important input parameter. For the development of design rules for the engineering of surfaces in contact with the skin an expression that describes the relation between the elastic
TENSILE DEFORMATION OF HIGH-STRENGTH AND HIGH MODULUS POLYETHYLENE FIBERS
VANDERWERFF, H; PENNINGS, AJ
The influence of tensile deformation on gel-spun and hot-drawn ultrahigh molecular weight polyethylene fibers has been investigated. In high modulus polyethylene fibers no deformation energy is used to break chemical bonds during deformation, and flow is predominantly present next to elastic
Influence of heat treatment and veneering on the storage modulus and surface of zirconia ceramic
Siavikis, G.; Behr, M.; van der Zel, J.M.; Feilzer, A.J.; Rosentritt, M.
2011-01-01
Objectives: Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of
Measurement of Young's modulus and Poisson's ratio of human hair using optical techniques
Hu, Zhenxing; Li, Gaosheng; Xie, Huimin; Hua, Tao; Chen, Pengwan; Huang, Fenglei
2010-03-01
Human hair is a complex nanocomposite fiber whose physical appearance and mechanical strength are governed by a variety of factors like ethnicity, cleaning, grooming, chemical treatments and environment. Characterization of mechanical properties of hair is essential to develop better cosmetic products and advance biological and cosmetic science. Hence the behavior of hair under tension is of interest to beauty care science. Human hair fibers experience tensile forces as they are groomed and styled. Previous researches about tensile testing of human hair were seemingly focused on the longitudinal direction, such as elastic modulus, yield strength, breaking strength and strain at break after different treatment. In this research, experiment of evaluating the mechanical properties of human hair, such as Young's modulus and Poisson's ratio, was designed and conducted. The principle of the experimental instrument was presented. The system of testing instrument to evaluate the Young's modulus and Poisson's ratio was introduced. The range of Poisson's ratio of the hair from the identical person was evaluated. Experiments were conducted for testing the mechanical properties after acid, aqueous alkali and neutral solution treatment of human hair. Explanation of Young's modulus and Poisson's ratio was conducted base on these results of experiments. These results can be useful to hair treatment and cosmetic product.
Bulk metallic glass formation in the Pd-Ni-P and Pd-Cu-P alloy systems
Energy Technology Data Exchange (ETDEWEB)
Schwarz, R.B.; He, Y. [Los Alamos National Lab., NM (United States). Center for Materials Science
1996-12-11
Bulk metallic glasses were prepared in the Pd-Ni-P and Pd-Cu-P systems using a fluxing technique. The formation of bulk amorphous Pd-Cu-P alloys was reported here for the first time. For both alloy systems, bulk glass formation requires maintaining the phosphorus content near 20 at.%. In the Pd-Ni-P system, 10-mm diameter amorphous Pd{sub x}Ni{sub 80{minus}x}P{sub 20} rods can be formed for 25 {le} x {le} 60. In the Pd-Cu-P system, 7-mm diameter amorphous Pd{sub x}Cu{sub 80{minus}x}P{sub 20} rods can be produced for 40 {le} x {le} 60. From all the ternary alloys studied, Pd{sub 40}Ni{sub 40}P{sub 20} has the highest glass formability, and 25-mm diameter amorphous cylinders, 50 mm in length, can be easily fabricated. The glass stability of the Pd-Ni-P system is wider than that of the Pd-Cu-P system. For most bulk Pd-Ni-P glasses, {Delta}T > 90 K. The {Delta}T values of bulk amorphous Pd-Cu-P alloys are considerably smaller, ranging from 27 to 73 K. The elastic constants of bulk amorphous Pd-Ni-P and Pd-Cu-P alloys were determined using a resonant ultrasound spectroscopy technique. The Pd-Ni-P glasses are slightly stiffer than the Pd-Cu-P glasses. Within each alloy system, the Young`s modulus and the bulk modulus show little change with alloy composition. Of all the bulk glass forming systems so far investigated, the ternary Pd-Ni-P system has the best glass formability. This alloy was one of the first bulk glasses discovered, yet it still remains the best in terms of glass formability. Upon replacing part of Ni by Cu, the critical cooling rates are expected to be further reduced.
MICROHARDNESS OF BULK-FILL COMPOSITE MATERIALS.
Kelić, Katarina; Matić, Sanja; Marović, Danijela; Klarić, Eva; Tarle, Zrinka
2016-12-01
The aim of the study was to determine microhardness of high- and low-viscosity bulk-fill composite resins and compare it with conventional composite materials. Four materials of high-viscosity were tested, including three bulk-fills: QuiXfi l (QF), x-tra fi l (XTF) and Tetric EvoCeram Bulk Fill (TEBCF), while nanohybrid composite GrandioSO (GSO) served as control. The other four were low-viscosity composites, three bulk-fill materials: Smart Dentin Replacement (SDR), Venus Bulk Fill (VBF) and x-tra base (XB), and conventional control material X-Flow (XF). Composite samples (n=5) were polymerized for 20 s with Bluephase G2 curing unit. Vickers hardness was used to determine microhardness of each material at the surface, and at 2-mm and 4-mm depth. GSO on average recorded significantly higher microhardness values than bulk-fill materials (pcomposite XF revealed similar microhardness values as SDR, but significantly lower than XB (pmaterials was lower than microhardness of the conventional composite material (GSO). Surface microhardness of low-viscosity materials was generally even lower. The microhardness of all tested materials at 4 mm was not different from their surface values. However, additional capping layer was a necessity for low-viscosity bulk-fill materials due to their low microhardness.
Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics
Directory of Open Access Journals (Sweden)
W. X. Niu
2013-01-01
Full Text Available Finite element analysis (FEA is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes in the computational simulation. A precise 3-dimensional finite element model was constructed based on an in-vitro specimen of human foot and ankle. Young’s moduli were assigned as four levels of 7.3, 14.6, 21.9 and 29.2 GPa respectively. The proximal tibia and fibula were completely limited to six degrees of freedom, and the ankle was loaded to inversion 10° and 20° through the calcaneus. Six cadaveric foot-ankle specimens were loaded as same as the finite element model, and strain was measured at two positions of the distal fibula. The bone stress was less affected by assignment of Young’s modulus. With increasing of Young’s modulus, the bone strain decreased linearly. Young’s modulus of 29.2 GPa was advisable to get the satisfactory surface strain results. In the future study, more ideal model should be constructed to represent the nonlinearity, anisotropy and inhomogeneity, as the same time to provide reasonable outputs of the interested parameters.
Quantitative study of the elastic modulus of loosely attached cells in AFM indentation experiments.
Dokukin, Maxim E; Guz, Nataliia V; Sokolov, Igor
2013-05-21
When measuring the elastic (Young's) modulus of cells using AFM, good attachment of cells to a substrate is paramount. However, many cells cannot be firmly attached to many substrates. A loosely attached cell is more compliant under indenting. It may result in artificially low elastic modulus when analyzed with the elasticity models assuming firm attachment. Here we suggest an AFM-based method/model that can be applied to extract the correct Young's modulus of cells loosely attached to a substrate. The method is verified by using primary breast epithelial cancer cells (MCF-7) at passage 4. At this passage, approximately one-half of cells develop enough adhesion with the substrate to be firmly attached to the substrate. These cells look well spread. The other one-half of cells do not develop sufficient adhesion, and are loosely attached to the substrate. These cells look spherical. When processing the AFM indentation data, a straightforward use of the Hertz model results in a substantial difference of the Young's modulus between these two types of cells. If we use the model presented here, we see no statistical difference between the values of the Young's modulus of both poorly attached (round) and firmly attached (close to flat) cells. In addition, the presented model allows obtaining parameters of the brush surrounding the cells. The cellular brush observed is also statistically identical for both types of cells. The method described here can be applied to study mechanics of many other types of cells loosely attached to substrates, e.g., blood cells, some stem cells, cancerous cells, etc. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Nimick, F.B.; Schwartz, B.M.
1987-09-01
Experimental data on matrix porosity, grain density, thermal expansion, compressive strength, Young`s modulus, Poisson`s ratio, and axial strain at failure for samples from the Topopah Spring Member of the Paintbrush Tuff are compiled. Heat capacity and emissivity also are discussed. Data have been analyzed for spatial variability; slight variability is observed for matrix porosity, grain density, and thermal expansion coefficient. Estimates of in situ values for some properties, such as bulk density and heat capacity, are presented. Vertical in situ stress as a function of horizontal and vertical location has been calculated. 96 refs., 37 figs., 27 tabs.
Effect of Contact Resistance on Bulk Resistivity of Dry Coke Beds
Eidem, P. A.; Runde, M.; Tangstad, M.; Bakken, J. A.; Zhou, Z. Y.; Yu, A. B.
2009-06-01
Measurements show that bulk resistivity of dry coke beds decreases with increasing particle size. A further development of a coke bed model is proposed to explain this correlation. By image analysis, it has been determined that the total porosity increases with increasing particle size. An increased total porosity of the particles decreases the mechanical strength of the particles. In the modeling work, the strength of the coke particles is introduced through Young’s modulus. By the use of discrete element method (DEM) modeling of a dry coke bed, the particle-to-particle contact area variation with varying particle size and particle strength has been introduced into a model of the dry coke bed. This was done by the introduction of the concept of the Holm’s radius, known from metal contact theory for describing how the contact resistance is affected by the material resistivity and the contact area. By assuming a decrease in the particle strength due to increased porosity of the coke particles with increasing particle size, the calculated bulk resistivity for 7.3-mm particles with a Young’s modulus of 1.0 GPa is 5.24·10-3 Ωm and 3.44·10-3 Ωm for the 20-mm particles with a Young’s modulus of 0.1 GPa. By comparison, the measured bulk resistivity of the Corus coke is 4.67 ± 0.30·10-3 Ωm for the 5- to 10-mm fraction and 3.71 ± 0.45·10-3 Ωm for the 15- to 20-mm fraction. The measured contact resistance of Swedish Steel AB (SSAB) coke decreases with increasing contact area size from a contact diameter of 5 mm to a contact diameter of 30 mm. This is probably due to an increasing number of electrical contact spots. When two spheres are in contact, the measured contact resistance is lower compared to the 5-mm-diameter contact, which indicates that the increased contact pressure has lowered the contact resistance. This supports the modeling results.
A brief overview of bulk metallic glasses
National Research Council Canada - National Science Library
Mingwei Chen
2011-01-01
The discovery of bulk metallic glasses (BMGs) has stimulated widespread research enthusiasm because of their technological promise for practical applications and scientific importance in understanding glass formation and glass phenomena...
Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine
2015-08-01
Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.
Boundary-bulk relation in topological orders
Kong, Liang; Wen, Xiao-Gang; Zheng, Hao
2017-09-01
In this paper, we study the relation between an anomaly-free n + 1D topological order, which are often called n + 1D topological order in physics literature, and its nD gapped boundary phases. We argue that the n + 1D bulk anomaly-free topological order for a given nD gapped boundary phase is unique. This uniqueness defines the notion of the "bulk" for a given gapped boundary phase. In this paper, we show that the n + 1D "bulk" phase is given by the "center" of the nD boundary phase. In other words, the geometric notion of the "bulk" corresponds precisely to the algebraic notion of the "center". We achieve this by first introducing the notion of a morphism between two (potentially anomalous) topological orders of the same dimension, then proving that the notion of the "bulk" satisfies the same universal property as that of the "center" of an algebra in mathematics, i.e. "bulk" = center". The entire argument does not require us to know the precise mathematical description of a (potentially anomalous) topological order. This result leads to concrete physical predictions.
Eldridge, Jeffrey I.; Zhu, Dong-Ming; Miller, Robert A.
2000-01-01
Cylindrical punch indentations are performed to determine the effective modulus of a plasma-sprayed ZrO2-8Wt%Y2O3 thermal barrier coating (TBC) as a function of coating depth. Cylindrical punch indentations offer significant advantages over pointed (Vickers, Berkovich, or Knoop) indentations for materials that do not exhibit linear elastic behavior. Cyclic loading with a cylindrical punch clearly shows the TBCs to exhibit nonlinear elastic behavior with significant hysteresis that is related to the compaction and internal sliding within the plasma-spray splat microstructure. In addition, the effect of a high heat flux laser treatment was shown to produce a gradient both in the effective TBC modulus and degree of loading/unloading hysteresis with depth.
Deriving tissue density and elastic modulus from microCT bone scans.
Wagner, David W; Lindsey, Derek P; Beaupre, Gary S
2011-11-01
Tissue level density and elastic modulus are intrinsic properties that can be used to quantify bone material and analyses incorporating those quantities have been used to evaluate bone on a macroscopic scale. Micro-computed tomography (microCT) technology has been used to construct tissue level finite element models to simulate macroscopic fracture strength, however, a single method for assigning voxel-specific tissue density and elastic modulus based on those data has not been universally accepted. One method prevalent in the literature utilizes an empirical relationship that derives tissue stiffness as a function of bone calcium content weight fraction. To derive calcium content weight fraction from microCT scans, a measure of tissue density is required and a constant value is traditionally used. However, experimental data suggest a non-trivial amount of tissue heterogeneity suggesting a constant tissue density may not be appropriate. A theoretical derivation for determining the relationship between voxel-specific tissue density and microCT scan data (i.e., microCT derived tissue mineral density (TMD), mgHA/cm(3)) and bone constituent properties is proposed. Constant model parameters used in the derivation include the density of water, ash, and organics (i.e., bone constituents) and the volume fraction of the organics constituent. The effect of incorporating the theoretically derived tissue density (instead of a constant value) in determining voxel-specific elastic modulus resulted in a maximum observed increase of 12GPa (5.9GPa versus 17.9GPa, for the constant value and derived tissue density formulations, respectively) for a measured TMD of 1.02gHA/cm(3). Average and bounding quantities for the four constant model parameters were defined from the literature and the influence of those values on the derived tissue density and elastic modulus relationships were also evaluated. The theoretical relationships of tissue density and elastic modulus, with the average
Anisotropy in the helicity modulus of a quantum three-dimensional XY model: application to YBCO
Energy Technology Data Exchange (ETDEWEB)
Mitrovic, Bozidar; Samokhin, Kirill; Bose, Shyamal K [Physics Department, Brock University, St Catharines, ON, L2S 3A1 (Canada)
2003-11-12
We present a variational study of the helicity moduli of an anisotropic quantum three-dimensional (3D) XY model of YBCO in its superconducting state. It is found that both the ab-plane and the c-axis helicity moduli, which are proportional to the inverse square of the corresponding magnetic field penetration depth, vary with temperature T as T{sup 4} in the zero temperature limit. Moreover, the c-axis helicity modulus drops with temperature much faster than the ab-plane helicity modulus because of the weaker Josephson couplings along the c-axis compared to those along the ab-plane. These findings are in disagreement with experiments on high quality samples of YBCO.
Effect of pH and Ibuprofen on Phopholipid Bilayer Bending Modulus
Boggara, Mohan; Faraone, Antonio; Krishnamoorti, Ramanan
2010-03-01
Non-steroidal anti-inflammatory drugs (NSAIDs) e.g. Aspirin and Ibuprofen, are known to cause gastrointestinal (GI) toxicity with chronic usage. However, NSAIDs pre-associated with phospholipids has been experimentally shown to reduce the GI toxicity and increase the therapeutic efficacy. In this study, using neutron spin-echo the effect of ibuprofen on the phospholipid membrane bending modulus is studied as a function of pH and temperature. Ibuprofen was found to lower the bending modulus at all pH values. We further present molecular insights into the observed effect on membrane dynamics based on structural studies using molecular dynamics simulations and small angle neutron scattering data as well as changes in zwitterionic headgroup electrostatics due to pH and addition of ibuprofen. This study is expected to help towards effective design of drug delivery nanoparticles based on variety of soft condensed matter such as lipids or polymers.
Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter.
Yue, Wenzhen; Zhang, Yan; Liu, Yimin; Xie, Jingwen
2016-06-17
Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter's power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods.
Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter
Directory of Open Access Journals (Sweden)
Wenzhen Yue
2016-06-01
Full Text Available Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter’s power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods.
Lukyanov, S. I.; Bandura, A. V.; Evarestov, R. A.
2015-12-01
Temperature dependence of the Young's modulus of cylindrical single-wall nanotubes with zigzag and armchair chiralities and consolidated-wall nanotubes has been studied by the molecular mechanics method with the use of the atom-atom potential. The nanotubes have been obtained by rolling up of crystal layers (111) of TiO2 with fluorite structure. Calculations have been performed for isothermal conditions on the basis of calculating the Helmholtz free energy of the system. The dependence of the Helmholtz free energy of nanotubes on the period has been calculated in the quasi-harmonic approximation as a result of calculation of phonon frequencies. It has been shown that the temperature dependence of the stiffness of nanotubes is determined by their chirality, and some nanotubes exibit anomalous behavior of both the Young's modulus and the period of unit cell with variation in temperature.
Energy Technology Data Exchange (ETDEWEB)
Ito, Masayuki [Waseda University Faculty of Science and Engineering, 3-4-1 Ookubo, Shinjuku-ku, Tokyo 169-8555 (Japan)], E-mail: masayuki@kurenai.waseda.jp; Oka, Toshitaka; Hama, Yosimasa [Waseda University Faculty of Science and Engineering, 3-4-1 Ookubo, Shinjuku-ku, Tokyo 169-8555 (Japan)
2009-12-15
'Generalized modulus-ultimate elongation profile' was induced from the relationship between the modulus and the ultimate elongation of an elastomer that was quantitatively added crosslinking and scission. This profile can be used to evaluate the time-accelerated irradiation methods of ethylene-propylene-diene elastomer. The irradiation under low dose rate (0.33 kGy/h) at room temperature was the reference condition. The short-time irradiation condition was 4.2 kGy/h in 0.5 MPa oxygen at room temperature and 5.0 kGy/h in air at 70 {sup o}C. The former tended to bring about the higher ratio of scission than the reference condition; the latter tended to bring about the higher ratio of crosslinking.
DEFF Research Database (Denmark)
Ding, Ming
2004-01-01
Bisphosphonates are emerging as an important treatment for osteoporosis. But whether the reduced fracture risk associated with bisphosphonate treatment is due to increased bone mass, improved trabecular architecture and/or increased secondary mineralization of the calcified matrix remains unclear...... for osteoporosis treatment. After one year, the dogs were killed, and samples from the first lumbar vertebrae were examined using a combination of micro-computed tomography, finite element modeling, and mechanical testing. By combining these methods, we examined the treatment effects on the calcified matrix...... matrix density, and increased microdamage. We could not detect any change in the effective Young's modulus of the calcified matrix in the bisphosphonate treated groups. The observed increase in apparent Young's modulus was due to increased bone mass and altered trabecular architecture rather than changes...
Hussain, Sadakat
Soy-based polyurethane foams (PUFs) were reinforced with fibres of different aspect ratios to improve the compressive modulus. Each of the three fibre types reinforced PUF differently. Shorter micro-crystalline cellulose fibres were found embedded inside the cell struts of PUF and reinforced them. The reinforcement was attributed to be stress transfer from the matrix to the fibre by comparing the experimental results to those predicted by micro-mechanical models for short fibre reinforced composites. The reinforced cell struts increased the overall compressive modulus of the foam. Longer glass fibres (470 microns, length) provided the best reinforcement. These fibres were found to be larger than the cell diameters. The micro-mechanical models could not predict the reinforcement provided by the longer glass fibres. The models predicted negligible reinforcement because the very low modulus PUF should not transfer load to the higher modulus fibres. However, using a finite element model, it was determined that the fibres were providing reinforcement through direct fibre interaction with each other. Intermediate length glass fibres (260 microns, length) were found to poorly reinforce the PUF and should be avoided. These fibres were too short to interact with each other and were on average too large to embed and reinforce cell struts. In order to produce natural fibre reinforced PUFs in the future, a novel device was invented. The purpose of the device is to deliver natural fibres at a constant mass flow rate. The device was found to consistently meter individual loose natural fibre tufts at a mass flow rate of 2 grams per second. However, the device is not robust and requires further development to deliver a fine stream of natural fibre that can mix and interact with the curing polymeric components of PUF. A design plan was proposed to address the remaining issues with the device.
Temperature, Frequency, and Young’s Modulus of an Aluminum Tuning Fork
Directory of Open Access Journals (Sweden)
Zachery L. Greer
2011-01-01
Full Text Available The frequency produced by a standard C (523.3 Hz aluminum alloy tuning fork when struck at temperatures ranging from 29 ̊C to 300 ̊C was studied. It was found that frequency decreased with increasing temperature with an inverse exponential relationship. The frequency was used to calculate Young’s Modulus for aluminum, with the results being in close agreement with published values.
An autonomic self-healing organogel with a photo-mediated modulus
Xiong, Yubing
2016-11-15
A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel. © 2016 The Royal Society of Chemistry.
Genetic variation in basic density and modulus of elasticity of coastal Douglas-fir.
G.R. Johnson; B.L. Gartner
2006-01-01
Douglas-fir trees from 39 open-pollinated families at four test locations were assessed to estimate heritability of modulus of elasticity (MOE) and basic density. Heritability estimates of MOE (across-site h = 0.55) were larger than those for total height (0.15) and diameter at breast height (DBH; 0.29), and similar to those for density (0.59)....
Khosravi Ali; Rahimi Mehrzad; Shahbazan Parisa; Pak Ali; Gheibi Amin
2016-01-01
Experimental studies have indicated that the small strain shear modulus, Gmax, of unsaturated silt and clay has a greater amount during imbibition than during drainage, when presented as a function of matric suction. However, due to material properties and inter-particle forces, different behavior is expected in the case of sand. Although considerable research has been devoted in recent years to characterize the behaviour of Gmax of sand during drainage, rather less attention has been paid to...
A vibrational approach to determine the elastic modulus of individual thin films in multilayers
Energy Technology Data Exchange (ETDEWEB)
López-Puerto, A. [Centro de Investigación Científica de Yucatán, A.C., Unidad de Materiales, Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán (Mexico); Universidad Autónoma de Yucatán, Facultad de Ingeniería, Av. Industrias no contaminantes por Periférico Norte, Cordemex, 97310 Mérida, Yucatán (Mexico); Avilés, F., E-mail: faviles@cicy.mx [Centro de Investigación Científica de Yucatán, A.C., Unidad de Materiales, Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán (Mexico); Gamboa, F.; Oliva, A.I. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Mérida, Depto. de Física Aplicada, Km. 6 Antigua Carretera a Progreso, 97310 Mérida, Yucatán (Mexico)
2014-08-28
A vibrational approach is presented to determine the elastic modulus of individual thin films deposited over a thicker substrate in multilayered systems. The approach requires measurement of the fundamental frequency of the multilayer and a laminated beam model for data reduction. A one-dimensional model based on classical laminated beam theory is introduced to provide a simple analytical approximation of the natural frequency of thin multilayered materials deposited over a significantly thicker substrate in cantilever beam configuration. The model has the advantage of providing an easy-to-use analytical expression for the natural frequency of a multilayered beam in terms of the elastic moduli of each layer, which can be inverted to calculate the elastic modulus of any individual layer if the elastic modulus of the remaining layers is known, and the natural frequency of the multilayered beam is measured. The limits of applicability of the proposed model are investigated by comparing its predictions of the fundamental frequency to those of an existent analytical model for bilayers and finite element analysis of materials comprising two and three dissimilar layers. The proposed model is applied to obtain the elastic modulus of Al and Au thin films in an Al/Au/Kapton multilayer. - Highlights: • A vibrational approach is proposed to measure elastic moduli of thin multilayers. • A vibratory model based on laminated theory is developed. • The model predictions of frequency are in agreement with finite element analysis. • The elastic moduli of Au and Al in an Al/Au/Kapton multilayer are measured.
Determination of Rock Mass Modulus Using the Plate Loading Method at Yucca Mountain, Nevada
Energy Technology Data Exchange (ETDEWEB)
Finley, R.E.; George, J.T.; Riggins, M.
1999-08-02
A suite of plate loading tests has recently been conducted by Sandia National Laboratories at the Exploratory Studies Facility at Yucca Mountain, Nevada. Fielding of these in situ tests as well as other approaches undertaken for the determination of rock mass modulus are described. The various methodologies are evaluated and their data compared. Calculation by existing empirical methods and numerical modeling are compared to each other as well as to field data.
Solving the {eta}-Problem in hybrid inflation with Heisenberg symmetry and stabilized modulus
Energy Technology Data Exchange (ETDEWEB)
Antusch, Stefan; Dutta, Koushik; Kostka, Philipp [Max-Planck-Institut fuer Physik, Werner-Heisenberg-Institut, Muenchen (Germany); Bastero-Gil, Mar [Departamento de Fisica Teorica y del Cosmos and Centro Andaluz de Fisica de Particulas Elementales, Universidad de Granada (Spain); King, Steve [School of Physics and Astronomy, University of Southampton (United Kingdom)
2009-07-01
We present a new class of models in which the {eta}-problem of supersymmetric hybrid inflation is resolved using a Heisenberg symmetry, where the associated modulus field is stabilized and made heavy with the help of the large vacuum energy during inflation without any fine-tuning. A natural candidate for the inflaton in this class of models is the right-handed sneutrino which is massless during the inflationary epoch, and subsequently acquires a large mass at the end of inflation.
Effects of Modulus and Modifying Agent on Aging of Water Glass
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Xu Hailan
2016-01-01
Full Text Available This paper studied the content of water glass before and after adding modifying agent by TMS-GC method, it was found that different modulus of water glass led to decrease of silicate content at different levels after a period of storage, and the modifying agent could retard the aging of water glass. It has remarkable significance on the theory and practical application of water glass chemistry.
Sumi, Chikayoshi
2005-10-01
We previously reported an ultrasonic strain measurement-based one-dimensional (1-D) shear modulus reconstruction technique using a regularization method for differential diagnosis of malignancies on human superficial tissues (e.g., breast tissues). Here, ultrasonic strain measurement-based 2-D and 3-D shear modulus reconstruction techniques are described, and the 1-D technique is reviewed and subsequently applied to various human in vivo tissues, including deeply situated tissues (e.g., liver). Because soft tissues are deformed in 3-D space by externally situated arbitrary mechanical sources, the accuracy of the low-dimensional (i.e., 1-D or 2-D) reconstructions is lower to that of 3-D reconstruction due to occurrence of erroneous reconstruction artifacts (i.e., the reconstructed modulus is different than reality). These artifacts are confirmed on simulated inhomogeneous cubic phantoms containing a spherical homogenous inclusion using numerically calculated deformation data. The superiority of quasi-real-time imaging of the shear modulus is then demonstrated by comparing it with conventional B-mode imaging and strain imaging from the standpoints of monitoring the effectiveness of minimally invasive thermal therapy as well as differential diagnosis. Because the 2-D and 3-D techniques require special ultrasonic (US) equipment, the 1-D technique using conventional US imaging equipment is used, even though erroneous artifacts will occur. Specifically, the 1-D technique is applied as a diagnostic tool for differentiating malignancies in human in vivo liver and breast tissue, and a monitoring technique for determining the effectiveness of interstitial electromagnetic wave (micro and rf) thermal therapy on human in vivo liver and calf in vitro liver. Even when using the 1-D technique, reconstructed shear moduli were confirmed to be a suitable measure for monitoring thermal treatment as well as differential diagnosis. These results are encouraging in that they will promote
In Vivo Quantification of the Nonlinear Shear Modulus in Breast Lesions: Feasibility Study.
Bernal, Miguel; Chamming's, Foucauld; Couade, Mathieu; Bercoff, Jeremy; Tanter, Mickaël; Gennisson, Jean-Luc
2016-01-01
Breast cancer detection in the early stages is of great importance since the prognosis, and the treatment depends more on this. Multiple techniques relying on the mechanical properties of soft tissues have been developed to help in early detection. In this study, we implemented a technique that measures the nonlinear shear modulus (NLSM) (μ(NL)) in vivo and showed its utility to detect breast lesions from healthy tissue. The technique relies on the acoustoelasticity theory in quasi-incompressible media. In order to recover μ(NL), static elastography and supersonic shear imaging are combined to subsequently register strain maps and shear modulus maps while the medium is compressed. Then, μ(NL) can be recovered from the relationship between the stress, deduced from strain maps, and the shear modulus. For this study, a series of five nonlinear phantoms were built using biological tissue (pork liver) inclusions immersed in an agar-gelatin gel. Furthermore, 11 in vivo acquisitions were performed to characterize the NLSM of breast tissue. The phantom results showed a very good differentiation of the liver inclusions when measuring μ(NL) with a mean value of -114.1 kPa compared to -34.7 kPa for the gelatin. Meanwhile, values for the shear modulus for the liver and the gelatin were very similar, 3.7 and 3.4 kPa, respectively. In vivo NLSM mean value for the healthy breast tissue was of -95 kPa, while mean values of the benign and the malignant lesions were -619 and -806 kPa with a strong v ariability, respectively. This study shows the potential of the acoustoelasticity theory in quasi-incompressible medium to bring a new parameter for breast cancer diagnosis.
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Mustafa Sarp Kaya
2018-01-01
Full Text Available ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs: a polywave third-generation (Valo; a monowave (DemiUltra: DU; and a second-generation LED (Optima 10: Opt LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC% was determined with Fourier-Transform Infrared Spectroscopy (FTIR. Microstructural features were observed with scanning electron microscopy (SEM. Flexural strength (FS, compression strength (CS, elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Opt
A first-principles DFT study of UN bulk and (001) surface: comparative LCAO and PW calculations.
Evarestov, R A; Bandura, A V; Losev, M V; Kotomin, E A; Zhukovskii, Yu F; Bocharov, D
2008-10-01
LCAO and PW DFT calculations of the lattice constant, bulk modulus, cohesive energy, charge distribution, band structure, and DOS for UN single crystal are analyzed. It is demonstrated that a choice of the uranium atom relativistic effective core potentials considerably affects the band structure and magnetic structure at low temperatures. All calculations indicate mixed metallic-covalent chemical bonding in UN crystal with U5f states near the Fermi level. On the basis of the experience accumulated in UN bulk simulations, we compare the atomic and electronic structure as well as the formation energy for UN(001) surface calculated on slabs of different thickness using both DFT approaches. (c) 2008 Wiley Periodicals, Inc.
A Six-Week Resistance Training Program Does Not Change Shear Modulus of the Triceps Brachii.
Akagi, Ryota; Shikiba, Tomofumi; Tanaka, Jun; Takahashi, Hideyuki
2016-08-01
We investigated the effect of a 6-week resistance training program on the shear modulus of the triceps brachii (TB). Twenty-three young men were randomly assigned to either the training (n = 13) or control group (n = 10). Before and after conducting the resistance training program, the shear modulus of the long head of the TB was measured at the point 70% along the length of the upper arm from the acromial process of the scapula to the lateral epicondyle of the humerus using shear wave ultrasound elastography. Muscle thickness of the long head of the TB was also determined at the same site by ultrasonography used during both tests. A resistance exercise was performed 3 days a week for 6 weeks using a dumbbell mass-adjusted to 80% of the 1-repetition maximum (1RM). The training effect on the muscle thickness and 1RM was significant. Nevertheless, the muscle shear modulus was not significantly changed after the training program. From the perspective of muscle mechanical properties, the present results indicate that significant adaptation must occur to make the TB more resistant to subsequent damaging bouts during the 6-week training program to target the TB.
Nano-fillers to tune Young's modulus of silicone matrix
Energy Technology Data Exchange (ETDEWEB)
Xia Lijin; Xu Zhonghua; Sun Leming; Caveney, Patrick M.; Zhang Mingjun, E-mail: mjzhang@utk.edu [University of Tennessee, Department of Mechanical, Aerospace and Biomedical Engineering (United States)
2013-04-15
In this study, we investigated nanoparticles, nanofibers, and nanoclays for their filler effects on tuning the Young's modulus of silicone matrix, a material with broad in vivo applications. Nano-fillers with different shapes, sizes, and surface properties were added into silicone matrix, and then their filler effects were evaluated through experimental studies. It was found that spherical nanoparticles could clearly improve Young's modulus of the silicone matrix, while nanoclays and carbon nanofibers had limited effects. Smaller spherical nanoparticles were better in performance compared to larger nanoparticles. In addition, enhanced distribution of the nanoparticles in the matrix has been observed to improve the filler effect. In order to minimize toxicity of the nanoparticles for in vivo applications, spherical nanoparticles coated with amine, acid, or hydroxide groups were also investigated, but they were found only to diminish the filler effect of nanoparticles. This study demonstrated that spherical nanoparticles could serve as fillers to tune Young's modulus of silicone matrix for potential applications in medicine.
Lu, Tao; Wen, Jin; Qian, Shi; Cao, Huiliang; Ning, Congqin; Pan, Xiaoxia; Jiang, Xinquan; Liu, Xuanyong; Chu, Paul K
2015-05-01
Polyetheretherketone (PEEK) possesses a similar elastic modulus as bones but yet suffers from bio-inertness and poor osteogenesis. In this work, tantalum ions are implanted energetically into PEEK by plasma immersion ion implantation (PIII) to form Ta2O5 nanoparticles in the near surface. Nanoindentation reveals that the surface elastic modulus of the Ta ion implanted PEEK is closer to that of human cortical bones. In vitro cell adhesion, alkaline phosphatase activity, collagen secretion, extracellular matrix mineralization, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells (bMSCs) on the Ta-PIII modified PEEK. In vivo evaluation of the cortico-cancellous rat femur model by means of micro-CT, sequential fluorescent labeling, and histological analysis after 8 weeks confirms significantly improved osteointegration. The bone-like elastic modulus and modified surface topography of the Ta-PIII modified PEEK synergistically induce osteogenic differentiation of bMSCs and the surface-modified materials have large potential in dental and orthopedic implants. Copyright © 2015 Elsevier Ltd. All rights reserved.
Galo, Rodrigo; Contente, Marta Maria Martins Giamatei; Galafassi, Daniel; Borsatto, Maria Cristina
2015-01-01
The purpose of this study was to determine the Young's modulus and the hardness of deciduous and permanent teeth following wear challenges using different dental materials. Wear challenges were performed against four dental materials: A resin-based fissure sealant (Fluoroshield(®)), a glass ionomer based fissure sealant (Vitremer(®)), and two microhybrid composite resins (Filtek Z250 and P90(®)). Using the pin-on-plate design, a deciduous or a permanent tooth was made into a pin (4 mm × 4 mm × 2 mm) working at a 3 N vertical load, 1 Hz frequency, and 900 cycles (15 min) with Fusayama artificial saliva as a lubricant. Before and after the tribological tests, the hardness and elasticity modulus of the tooth samples were measured by creating a nanoindentation at load forces up to 50 mN and 150 mN. All of the results were statistically analyzed using ANOVA and post-hoc Duncan's tests (P modulus of elasticity (P < 0.05) before or after the wear challenges for all of the dental materials tested. Wear challenges against the studied dental materials did not alter the properties of permanent or deciduous teeth after the application of a 3 N load.
Indentation modulus and hardness of viscoelastic thin films by atomic force microscopy: A case study
Energy Technology Data Exchange (ETDEWEB)
Passeri, D., E-mail: daniele.passeri@uniroma1.it [Dipartimento di Energetica, Universita di Roma ' La Sapienza' , Via A. Scarpa 16, 00161 Roma (Italy); Bettucci, A.; Biagioni, A.; Rossi, M.; Alippi, A. [Dipartimento di Energetica, Universita di Roma ' La Sapienza' , Via A. Scarpa 16, 00161 Roma (Italy); Tamburri, E. [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 00133 Roma (Italy); Lucci, M.; Davoli, I. [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 00133 Roma (Italy); Berezina, S. [Department of Physics, University of Zilina, 01026, Univerzitna 1 Zilina (Slovakia)
2009-11-15
We propose a nanoindentation technique based on atomic force microscopy (AFM) that allows one to deduce both indentation modulus and hardness of viscoelastic materials from the force versus penetration depth dependence, obtained by recording the AFM cantilever deflection as a function of the sample vertical displacement when the tip is pressed against (loading phase) and then removed from (unloading phase) the surface of the sample. Reliable quantitative measurements of both indentation modulus and hardness of the investigated sample are obtained by calibrating the technique through a set of different polymeric samples, used as reference materials, whose mechanical properties have been previously determined by standard indentation tests. By analyzing the dependence of the cantilever deflection versus time, the proposed technique allows one to evaluate and correct the effect of viscoelastic properties of the investigated materials, by adapting a post-experiment data processing procedure well-established for standard depth sensing indentation tests. The technique is described in the case of the measurement of indentation modulus and hardness of a thin film of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate), deposited by chronoamperometry on an indium tin oxide (ITO) substrate.
Determination of elastic modulus for hollow spherical shells via resonant ultrasound spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Ma, Xiaojun [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Xing; Wang, Zongwei [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Chen, Qian; Qian, Menglu [Institute of Acoustic, Tongji University, Shanghai 200092 (China); Meng, Jie [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Yongjian [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Shen, Hao [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Gao, Dangzhong, E-mail: dgaocn@163.com [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)
2017-04-15
Highlights: • The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method. • The simulated results demonstrate that the natural frequencies of a hollow sphere are more strongly dependent on Young’s modulus than Poisson's ratio. • The Young’s moduli of polymer capsules with an sub-millimeter inner radius are measured accurately with an uncertainty of ∼10%. - Abstract: The elastic property of a capsule is one of the essential parameters both in engineering applications and scientific understanding of material nature in inertial confinement fusion (ICF) experiments. The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method, and a combined resonant ultrasound spectroscopy(RUS), which consists of a piezoelectric-based resonant ultrasound spectroscopy(PZT-RUS) and a laser-based resonant ultrasound spectroscopy(LRUS), is developed for determining the elastic modulus of capsule. To understand the behavior of natural frequencies varying with elastic properties, the dependence of natural frequencies on Young’s modulus and Poisson’s ratio are calculated numerically. Some representative polymer capsules are measured using PZT-RUS and LRUS. Based on the theoretical and experimental results, the Young’s moduli of these capsules are measured accurately with an uncertainty of ∼10%.
Influence of grain size distribution on dynamic shear modulus of sands
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Dyka Ireneusz
2017-11-01
Full Text Available The paper presents the results of laboratory tests, that verify the correlation between the grain-size characteristics of non-cohesive soils and the value of the dynamic shear modulus. The problem is a continuation of the research performed at the Institute of Soil Mechanics and Rock Mechanics in Karlsruhe, by T. Wichtmann and T. Triantafyllidis, who derived the extension of the applicability of the Hardin’s equation describing the explicite dependence between the grain size distribution of sands and the values of dynamic shear modulus. For this purpose, piezo-ceramic bender elements generating elastic waves were used to investigate the mechanical properties of the specimens with artificially generated particle distribution. The obtained results confirmed the hypothesis that grain size distribution of non-cohesive soils has a significant influence on the dynamic shear modulus, but at the same time they have shown that obtaining unambiguous results from bender element tests is a difficult task in practical applications.
Mendapatkan Young’s Modulus Fasa Cu6Sn5 dengan Teknik Ultrasonik dan Teori Komposit
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Ellyza Herda
2015-09-01
Full Text Available The purpose of this study is to obtain the Young’s Modulus (elastic property of Cu6Sn5 phase by using ultrasonic technique and composite theory. Alloy with the following composition (weight percent = wt%: 15.00 % Cu and 85 % Sn was fabricated by casting method. Phases identification were determined by using X-ray Diffraction (XRD, Differential Scanning Calorimeter (DSC, and Scanning Electron Microscope (SEM + EDAX (Energy Dispersive X-ray Analysis. A non destructive technique is preferable evaluation method for evaluation the elastic property of material, that is by utilizing longitudinal and transversal waves velocity employed by ultrasonic pulse-echo method. X-ray diffraction, DSC, and SEM+EDAX analysis indicate that the fabricated Cu-85%Sn alloy produce a composite in situ material which consist of Sn as a matrix (0.67 volume fraction and Cu6Sn5 phase as a reinforcing material (0.33 volume fraction. The Young’s Modulus value of Cu-85%Sn is 67.7 GPa. This value is base on the calculating result on the longitudinal and transversal waves velocity. In order to obtain the Young’s Modulus of reinforcement (Cu6Sn5 phase the composite theory was applied to this material (Cu-85%Sn, and the resulted value is 103.8 GPa.
Measurement of Young’s Modulus and Internal Damping of Pork Muscle in Dynamic Mode
Chakroun, Moez; Ghozlen, Med Hédi Ben
2016-09-01
Automotive shocks involve various tiers’ speed for different human body tissues. Knowing the behavior of these tissues, including muscles, in different vibration frequency is therefore necessary. The muscle has viscoelatic properties. Dynamically, this material has variable mechanical properties depending on the vibration frequency. A novel technique is being employed to examine the variation of the mechanical impedance of pork muscle as a function of frequency. A force is imposed on the lower surface of the sample and acceleration is measured on its upper surface. These two parameters are measured using sensors. The sample is modeled by Kelvin-Voigt model. These measures allow deducing the change in the mechanical impedance modulus (/Zexp/ = /Force: Acceleration/) of pork muscle as a function of vibration frequency. The measured impedance has a resonance of approximately 60Hz. Best-fit parameters of theoretical impedance can be deduced by superposition with the experiment result. The variation of Young’s modulus and internal damping of pig’s muscle as a function of frequency are determined. The results obtained between 5Hz and 30Hz are the same as determined by Aimedieu and al in 2003, therefore validating our technique. The Young’s modulus of muscle increases with the frequency, on the other hand, we note a rating decrease of internal damping.
Determination of relaxation modulus of time-dependent materials using neural networks
Aulova, Alexandra; Govekar, Edvard; Emri, Igor
2017-08-01
Health monitoring systems for plastic based structures require the capability of real time tracking of changes in response to the time-dependent behavior of polymer based structures. The paper proposes artificial neural networks as a tool of solving inverse problem appearing within time-dependent material characterization, since the conventional methods are computationally demanding and cannot operate in the real time mode. Abilities of a Multilayer Perceptron (MLP) and a Radial Basis Function Neural Network (RBFN) to solve ill-posed inverse problems on an example of determination of a time-dependent relaxation modulus curve segment from constant strain rate tensile test data are investigated. The required modeling data composed of strain rate, tensile and related relaxation modulus were generated using existing closed-form solution. Several neural networks topologies were tested with respect to the structure of input data, and their performance was compared to an exponential fitting technique. Selected optimal topologies of MLP and RBFN were tested for generalization and robustness on noisy data; performance of all the modeling methods with respect to the number of data points in the input vector was analyzed as well. It was shown that MLP and RBFN are capable of solving inverse problems related to the determination of a time dependent relaxation modulus curve segment. Particular topologies demonstrate good generalization and robustness capabilities, where the topology of RBFN with data provided in parallel proved to be superior compared to other methods.
Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.
2017-11-01
One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.
A Comparative Study of Solutions Concerning Thick Elastic Plates on Bi-modulus Foundation
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Ioana Vlad
2004-01-01
Full Text Available The classical bending theory of elastic plates is based upon the assumption that the internal moments are proportional to the curvatures of the median deformed surface. This theory does not include the effects of shear and normal pressure in the plate. The model of a bi-modulus foundation is a realistic generalization of the Winkler’s classical one and is widely used to represent the subgrade of railroad systems, airport lanes [1], [2]. The derived equation of elastic thick plates on bi-modulus foundation considers shear and normal stress as linear variable across the plate thickness. This paper presents numerical solutions for thick plate resting on bi-modulus subgrade. These solutions take into account the shear distortion, and they are compared to the solution obtained by Finite Element Analysis and with the Winkler’s model. Particular solutions for the rectangular plate of clamped boundary, for the hinged rectangular plate and for a semi-elliptical plate, are discussed. The numerical solutions consist of double power series and they were obtained based on the minimum of the total strain energy [1]. Parametric studies have been performed in order to emphasize the effects of the chosen foundation and that of the geometry.
Fast, High Resolution, and Wide Modulus Range Nanomechanical Mapping with Bimodal Tapping Mode.
Kocun, Marta; Labuda, Aleksander; Meinhold, Waiman; Revenko, Irène; Proksch, Roger
2017-10-24
Tapping mode atomic force microscopy (AFM), also known as amplitude modulated (AM) or AC mode, is a proven, reliable, and gentle imaging mode with widespread applications. Over the several decades that tapping mode has been in use, quantification of tip-sample mechanical properties such as stiffness has remained elusive. Bimodal tapping mode keeps the advantages of single-frequency tapping mode while extending the technique by driving and measuring an additional resonant mode of the cantilever. The simultaneously measured observables of this additional resonance provide the additional information necessary to extract quantitative nanomechanical information about the tip-sample mechanics. Specifically, driving the higher cantilever resonance in a frequency modulated (FM) mode allows direct measurement of the tip-sample interaction stiffness and, with appropriate modeling, the set point-independent local elastic modulus. Here we discuss the advantages of bimodal tapping, coined AM-FM imaging, for modulus mapping. Results are presented for samples over a wide modulus range, from a compliant gel (∼100 MPa) to stiff materials (∼100 GPa), with the same type of cantilever. We also show high-resolution (subnanometer) stiffness mapping of individual molecules in semicrystalline polymers and of DNA in fluid. Combined with the ability to remain quantitative even at line scan rates of nearly 40 Hz, the results demonstrate the versatility of AM-FM imaging for nanomechanical characterization in a wide range of applications.
Determination of crystallographic young’s modulus for sheet metals by in situ neutron diffraction
Vitzthum, S. J.; Hartmann, C.; Weiss, H. A.; Baumgartner, G.; Hofmann, M.; Volk, W.
2017-09-01
Elastic recovery is an important issue in sheet metal forming, especially in the context of the upcoming use of high strength steels due to shifted relations between Young’s modulus and strength. One important factor when it comes to elastic recovery prediction is a deep understanding for the elasto-plastic characteristics of the material. Today in general simple elastic behavior with constant Young’s modulus and Poisson’s ratio is assumed. Macroscopic analysis in standard tests shows that these assumptions are insufficient for an appropriate prediction of elastic recovery in sheet metal forming, which is why different phenomenological correlation models are derived. An experimental setup and microscopic investigation to further prove these models and to verify the approaches on another scale for sheet metals is presented within this paper. In the study microscopic deformation behavior of loading and unloading of a HC260LA sheet metal is analysed using in-situ neutron diffraction. Based on the lattice plane strains an orientation specific crystallographic Young’s modulus for different rolling directions is determined.
The effect of a running task on muscle shear elastic modulus of posterior lower leg.
Ohya, Shuhei; Nakamura, Masatoshi; Aoki, Takafumi; Suzuki, Daichi; Kikumoto, Takanori; Nakamura, Emi; Ito, Wataru; Hirabayashi, Ryo; Takabayashi, Tomoya; Edama, Mutsuaki
2017-01-01
Medial tibial stress syndrome (MTSS) is one of the most common causes of exercise-related leg pain in runners. Because stopping training due to pain from MTSS could decrease the athlete's competitiveness, it is necessary to construct MTSS prevention and treatment programs. However, the effect of running, which is believed to cause MTSS, on shear elastic modulus of the posterior lower leg is unclear. Therefore, the purpose of this study was to investigate the effect of 30 min of running on shear elastic modulus of the posterior lower leg in healthy subjects. Twenty healthy males volunteered to participate in this study (age, 20.9 ± 0.6 y; height, 169.6 ± 4.5 cm; weight, 62.6 ± 5.2 kg). The shear elastic modulus of the posterior lower leg was measured using ultrasonic shear wave elastography before and immediately after a 30-min running task. Shear elastic moduli of the flexor digitorum longus and tibialis posterior were significantly increased after 30 min running task. However, there were no significant changes in shear elastic moduli of the lateral gastrocnemius, medial gastrocnemius, peroneus longus and peroneus brevis. The results suggested that the increases in shear elastic moduli of flexor digitorum longus and tibialis posterior after running could be a risk factor for running-related MTSS development.
Samani, Abbas; Plewes, Donald
2007-03-07
Soft tissue elasticity has been a subject of interest in biomedical applications as an aid to medical diagnosis since the dawn of medicine. More recently, this has led to the concept of elastography with the aim of imaging the spatial distribution of tissue elasticity. Interpreting elastography images requires reliable information pertaining to elastic properties of normal and pathological tissues. Such information is either very limited or not available in the literature. Elastic modulus measurement techniques developed for soft tissues generally require tissue excision to prepare samples for testing. While this may be done with normal tissues, tumour tissue excision is generally not permissible because tumour pathological assessment requires that the tumour be kept intact. To address this limitation, we developed a system to measure the Young's modulus of tumour specimens. The technique consists of indenting the tumour specimen while measuring indentation force and displacements. To obtain the Young's modulus from the measured force-displacement slope, we developed an iterative inversion technique that uses a finite element model of the piecewise homogeneous tissue slice in each iteration. Preliminary elasticity measurement results of various breast tumours are presented and discussed. These results indicate that the proposed method is robust and highly accurate. Furthermore, they indicate that a benign lesion and malignant tumours are roughly five times and ten times stiffer than normal breast tissues respectively.
Energy Technology Data Exchange (ETDEWEB)
Samani, Abbas [Department of Medical Biophysics/Electrical and Computer Engineering, University of Western Ontario, London, Ontario, N6A 5C1 (Canada); Plewes, Donald [Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5 (Canada)
2007-03-07
Soft tissue elasticity has been a subject of interest in biomedical applications as an aid to medical diagnosis since the dawn of medicine. More recently, this has led to the concept of elastography with the aim of imaging the spatial distribution of tissue elasticity. Interpreting elastography images requires reliable information pertaining to elastic properties of normal and pathological tissues. Such information is either very limited or not available in the literature. Elastic modulus measurement techniques developed for soft tissues generally require tissue excision to prepare samples for testing. While this may be done with normal tissues, tumour tissue excision is generally not permissible because tumour pathological assessment requires that the tumour be kept intact. To address this limitation, we developed a system to measure the Young's modulus of tumour specimens. The technique consists of indenting the tumour specimen while measuring indentation force and displacements. To obtain the Young's modulus from the measured force-displacement slope, we developed an iterative inversion technique that uses a finite element model of the piecewise homogeneous tissue slice in each iteration. Preliminary elasticity measurement results of various breast tumours are presented and discussed. These results indicate that the proposed method is robust and highly accurate. Furthermore, they indicate that a benign lesion and malignant tumours are roughly five times and ten times stiffer than normal breast tissues respectively.
Propagation of bulk longitudinal waves in thin films using laser ultrasonics
Energy Technology Data Exchange (ETDEWEB)
Kim, Yun Young [Dept. of Mechanical Engineering, Dong-eui University, Busan (Korea, Republic of)
2016-08-15
This paper presents the investigation of the propagation behavior of bulk longitudinal waves generated by an ultrafast laser system in thin films. A train of femtosecond laser pulses was focused onto the surface of a 150-nm thick metallic (chromium or aluminum) film on a silicon substrate to excite elastic waves, and the change in thermoreflectance at the spot was monitored to detect the arrival of echoes from the film/substrate interface. The experimental results show that the film material characteristics such as the wave velocity and Young's modulus can be evaluated through curve-fitting in numerical solutions. The material properties of nanoscale thin films are difficult to measure using conventional techniques. Therefore, this research provides an effective method for the nondestructive characterization of nanomaterials.
The bulk, surface and corner free energies of the square lattice Ising model
Baxter, R. J.
2017-01-01
We use Kaufman’s spinor method to calculate the bulk, surface and corner free energies {f}{{b}},{f}{{s}},{f}{{s}}\\prime ,{f}{{c}} of the anisotropic square lattice zero-field Ising model for the ordered ferromagnetic case. For {f}{{b}},{f}{{s}},{f}{{s}}\\prime our results of course agree with the early work of Onsager, McCoy and Wu. We also find agreement with the conjectures made by Vernier and Jacobsen (VJ) for the isotropic case. We note that the corner free energy f c depends only on the elliptic modulus k that enters the working, and not on the argument v, which means that VJ’s conjecture applies for the full anisotropic model. The only aspect of this paper that is new is the actual derivation of f c, but by reporting all four free energies together we can see interesting structures linking them.
Poly(acrylic acid surface grafted polypropylene films: Near surface and bulk mechanical response
Directory of Open Access Journals (Sweden)
2008-11-01
Full Text Available Radical photo-grafting polymerization constitutes a promising technique for introducing functional groups onto surfaces of polypropylene films. According to their final use, surface grafting should be done without affecting overall mechanical properties. In this work the tensile drawing, fracture and biaxial impact response of biaxially oriented polypropylene commercial films grafted with poly(acrylic acid (PAA were investigated in terms of film orientation and surface modification. The variations of surface roughness, elastic modulus, hardness and resistance to permanent deformation induced by the chemical treatment were assessed by depth sensing indentation. As a consequence of chemical modification the optical, transport and wettability properties of the films were successfully varied. The introduced chains generated a PAA-grafted layer, which is stiffer and harder than the neat polypropylene surface. Regardless of the surface changes, it was proven that this kind of grafting procedure does not detriment bulk mechanical properties of the PP film.
Novel Approach in the Use of Plasma Spray: Preparation of Bulk Titanium for Bone Augmentations
Directory of Open Access Journals (Sweden)
Michaela Fousova
2017-08-01
Full Text Available Thermal plasma spray is a common, well-established technology used in various application fields. Nevertheless, in our work, this technology was employed in a completely new way; for the preparation of bulk titanium. The aim was to produce titanium with properties similar to human bone to be used for bone augmentations. Titanium rods sprayed on a thin substrate wire exerted a porosity of about 15%, which yielded a significant decrease of Young′s modulus to the bone range and provided rugged topography for enhanced biological fixation. For the first verification of the suitability of the selected approach, tests of the mechanical properties in terms of compression, bending, and impact were carried out, the surface was characterized, and its compatibility with bone cells was studied. While preserving a high enough compressive strength of 628 MPa, the elastic modulus reached 11.6 GPa, thus preventing a stress-shielding effect, a generally known problem of implantable metals. U-2 OS and Saos-2 cells derived from bone osteosarcoma grown on the plasma-sprayed surface showed good viability.
Integration of bulk piezoelectric materials into microsystems
Aktakka, Ethem Erkan
Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.
Development of superconductor bulk for superconductor bearing
Energy Technology Data Exchange (ETDEWEB)
Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong (and others)
2008-08-15
Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C {approx} 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm{sup 2} using TSMG processing technique.
Influence of heat treatment and veneering on the storage modulus and surface of zirconia ceramic.
Siavikis, Georgius; Behr, Michael; van der Zel, Jef M; Feilzer, Albert J; Rosentritt, Martin
2011-04-01
Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of zirconia. Zirconia bars (Cercon, DeguDent, G; 0.5x2x20 mm) were fabricated and treated according to veneering conditions. Besides heating regimes between 680°C and 1000°C (liner bake and annealing), sandblasting (Al(2)O(3)) or steam cleaning were used. The bars were investigated after 90 days storage in water and acid. For investigating the influence of veneering, the bars were veneered in press- or layer technique. Dynamic mechanical analysis (DMA) in a three-point-bending design was performed to determine the storage modulus between 25°C and 200°C at a frequency of 1.66 Hz. All specimens were loaded on top and bottom (treatment on pressure or tensile stress side). Scanning electron microscopy (SEM) was used for evaluating the superficial changes of the zirconia surface due to treatment. Statistical analysis was performed using Mann Whitney U-test (α=0.05). Sintered zirconia provided a storage modulus E' of 215 (203/219) GPa and tan δ of 0.04 at 110°C. A 10%-decrease of E' was found up to 180°C. The superficial appearance changed due to heating regime. Sandblasting reduced E' to 213 GPa, heating influenced E' between 205 GPa (liner bake 1) and 222 GPa (dentin bake 1). Steam cleaning, annealing and storage changed E' between 4 GPa and 22 GPa, depending on the side of loading. After veneering, strong E'-reduction was found down to 84 GPa and 125 GPa. Veneering of zirconia with glass-ceramic in contrast to heat treating during veneering procedure had a strong influence on the modulus. The application of the glass-ceramic caused a stronger decrease of the storage modulus.
Wang, Xiaojun; Li, Xiaona; Chen, Weiyi; He, Rui; Gao, Zhipeng; Feng, Pengfei
2017-01-17
The biomechanical properties of the cornea should be taken into account in the refractive procedure in order to perform refractive surgery more accurately. The effects of the ablation depth and repair time on the elastic modulus of the rabbit cornea after laser in situ keratomileusis (LASIK) are still unclear. In this study, LASIK was performed on New Zealand rabbits with different ablation depth (only typical LASIK flaps were created; residual stroma bed was 50 or 30% of the whole cornea thickness respectively). The animals without any treatment were served as normal controls. The corneal thickness was measured by ultrasonic pachymetry before animals were humanly killed after 7 or 28 days post-operatively. The corneal elastic modulus was measured by uniaxial tensile testing. A mathematical procedure considering the actual geometrics of the cornea was created to analyze the corneal elastic modulus. There were no obvious differences among all groups in the elastic modulus on after 7 days post-operatively. However, after 28th days post-operatively, there was a significant increase in the elastic modulus with 50 and 30% residual stroma bed; only the elastic modulus of the cornea with 30% residual stroma bed was significantly higher than that of 7 days. Changes in elastic modulus after LASIK suggest that this biomechanical effect may correlate with the ablation depth and repair time.
Predicting bulk mechanical properties of cellularized collagen gels using multiphoton microscopy
Raub, CB; Putnam, AJ; Tromberg, BJ; George, SC
2012-01-01
Cellularized collagen gels are a common model in tissue engineering, but the relationship between the microstructure and bulk mechanical properties is only partially understood. Multiphoton microscopy (MPM) is an ideal non-invasive tool to examine collagen microstructure, cellularity and crosslink content in these gels. In order to identify robust image parameters that characterize microstructural determinants of the bulk elastic modulus, we performed serial MPM and mechanical tests on acellular and cellularized (normal human lung fibroblasts) collagen hydrogels, before and after glutaraldehyde crosslinking. Following gel contraction over sixteen days, cellularized collagen gel content approached that of native connective tissues (~200 mg/ml). Young’s modulus (E) measurements from acellular collagen gels (range 0.5-12 kPa) exhibited a power-law concentration dependence (range 3-9 mg/ml) with exponents from 2.1-2.2, similar to other semiflexible biopolymer networks such as fibrin and actin. In contrast, cellularized collagen gel stiffness (range 0.5-27 kPa) produced concentration-dependent exponents of 0.7 uncrosslinked and 1.1 crosslinked (range ~5-200 mg/ml). The variation in E of cellularized collagen hydrogels can be explained by a power-law dependence on robust image parameters: either the second harmonic generation (SHG) and two-photon fluorescence (TPF) (matrix component) skewness (R2 = 0.75, exponents of −1.0 and −0.6, respectively); or alternately the SHG and TPF (matrix component) speckle contrast (R2 = 0.83, exponents of −0.7 and −1.8, respectively). Image parameters based on the cellular component of TPF signal did not improve the fits. The concentration dependence of E suggests enhanced stress relaxation in cellularized versus acellular gels. SHG and TPF image skewness and speckle contrast from cellularized collagen gels can predict E by capturing mechanically relevant information on collagen fiber, cell and crosslink density. PMID:20620246
Holographic bulk reconstruction with α' corrections
Roy, Shubho R.; Sarkar, Debajyoti
2017-10-01
We outline a holographic recipe to reconstruct α' corrections to anti-de Sitter (AdS) (quantum) gravity from an underlying CFT in the strictly planar limit (N →∞ ). Assuming that the boundary CFT can be solved in principle to all orders of the 't Hooft coupling λ , for scalar primary operators, the λ-1 expansion of the conformal dimensions can be mapped to higher curvature corrections of the dual bulk scalar field action. Furthermore, for the metric perturbations in the bulk, the AdS /CFT operator-field isomorphism forces these corrections to be of the Lovelock type. We demonstrate this by reconstructing the coefficient of the leading Lovelock correction, also known as the Gauss-Bonnet term in a bulk AdS gravity action using the expression of stress-tensor two-point function up to subleading order in λ-1.
Bulk amorphous Mg-based alloys
DEFF Research Database (Denmark)
Pryds, Nini
2004-01-01
and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface......The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...
Orchestrating Bulk Data Movement in Grid Environments
Energy Technology Data Exchange (ETDEWEB)
Vazhkudai, SS
2005-01-25
Data Grids provide a convenient environment for researchers to manage and access massively distributed bulk data by addressing several system and transfer challenges inherent to these environments. This work addresses issues involved in the efficient selection and access of replicated data in Grid environments in the context of the Globus Toolkit{trademark}, building middleware that (1) selects datasets in highly replicated environments, enabling efficient scheduling of data transfer requests; (2) predicts transfer times of bulk wide-area data transfers using extensive statistical analysis; and (3) co-allocates bulk data transfer requests, enabling parallel downloads from mirrored sites. These efforts have demonstrated a decentralized data scheduling architecture, a set of forecasting tools that predict bandwidth availability within 15% error and co-allocation architecture, and heuristics that expedites data downloads by up to 2 times.
Kaforey, M. L.; Deeb, C. W.; Matthiesen, D. H.
1999-01-01
A theoretical equation was derived to predict the spring constant (load/deflection) for a simply supported cylindrical section with a line force applied at the center. Curved leaves of PBN were mechanically deformed and the force versus deflection data was recorded and compared to the derived theoretical equation to yield an effective modulus for each leaf. The effective modulus was found to vary from the pure shear modulus for a flat plate to a mixed mode for a half cylinder as a function of the sine of one half the angular leaf span. The spring constants of individual PBN leaves were usually predicted to within 30%.
Ueng, Tzou-Shin; Chen, Jian-Chu
1992-07-01
A computer code, RAMBO, is developed for obtaining the values of parameters in the Ramberg-Osgood elastoplastic model based on data of shear modulus and damping ratio at various shear strains. The basis and procedures for finding the parameters for the best fit of the data or relations defining modulus and damping ratios versus shear strain are given in this report. The Ramberg-Osgood relationship is rearranged so that the results can best fit data of both modulus and damping ratio. Constraints of data in the model are also discussed.
Thermal relics in cosmology with bulk viscosity
Energy Technology Data Exchange (ETDEWEB)
Iorio, A. [Charles University in Prague, Faculty of Mathematics and Physics, Prague (Czech Republic); Lambiase, G. [Universita di Salerno, Dipartimento di Fisica E.R. Caianiello, Fisciano (Italy); INFN, Gruppo Collegato di Salerno, Fisciano (Italy)
2015-03-01
In this paper we discuss some consequences of cosmological models in which the primordial cosmic matter is described by a relativistic imperfect fluid. The latter takes into account the dissipative effects (bulk viscosity) arising from different cooling rates of the fluid components in the expanding Universe. We discuss, in particular, the effects of the bulk viscosity on Big Bang Nucleosynthesis and on the thermal relic abundance of particles, looking at recent results of PAMELA experiment. The latter has determined an anomalous excess of positron events, which cannot be explained by conventional cosmology and particle physics. (orig.)
A mechanistic analysis of bulk powder caking
Calvert, G.; Curcic, N.; Ghadiri, M.
2013-06-01
Bulk powder transformations, such as caking, can lead to numerous problems within industry when storing or processing materials. In this paper a new Environmental Caking Rig (ECR) is introduced and has been used to evaluate the caking propensity of a hygroscopic powder as a function of temperature, Relative Humidity (RH), mechanical stress and also when RH is cycled. A linear relationship exists between cake strength and the extent of bulk deformation, here defined by the engineering strain. An empirical model has been used to predict the caking behaviour based on consolidation stress and environmental conditions.
Synthesis of Bulk Superconducting Magnesium Diboride
Directory of Open Access Journals (Sweden)
Margie Olbinado
2002-06-01
Full Text Available Bulk polycrystalline superconducting magnesium diboride, MgB2, samples were successfully prepared via a one-step sintering program at 750°C, in pre Argon with a pressure of 1atm. Both electrical resistivity and magnetic susceptibility measurements confirmed the superconductivity of the material at 39K, with a transition width of 5K. The polycrystalline nature, granular morphology, and composition of the sintered bulk material were confirmed using X-ray diffractometry (XRD, scanning electron microscopy (SEM, and energy dispersive X-ray analysis (EDX.
Energy Technology Data Exchange (ETDEWEB)
Adachi, H.; Hasegawa, T. [Nagoya Municipal Industrial Research Inst., Aichi (Japan)
1998-09-15
The relation between dynamic compression modulus and hardness and repulsive elastic modulus of flexible polyurethane foam was investigated by viscoelasticity measurement. The dynamic compression modulus varies depending on the initial shrinkage. In a larger shrinkage region, its increase was remarkably large. The dynamic compression modulus is positively correlated with the hardness, but it is reversely correlated with the repulsive elastic modulus. The dynamic compression modulus can be effectively used for evaluating the product quality. A simple two-dimensional model is proposed for flexible polyurethane foam. To the model, the finite element method (FEM) employing the plane stress element was applied. The calculated Young modulus from the model agrees well with calculated values of Thomas-Gent and of Lederman. However, it was significantly larger than the dynamic modulus. A FEM analysis employing plane rahmen element considering the skeleton bending was also performed. 15 refs., 8 figs., 1 tab.
Cellulosic ethanol byproducts as a bulking agent
J.M. Considine; D. Coffin; J.Y. Zhu; D.H. Mann; X. Tang
2017-01-01
Financial enhancement of biomass value prior to pulping requires subsequent use of remaining materials; e.g., high value use of remaining stock material after cellulosic ethanol production would improve the economics for cellulosic ethanol. In this work, use of enzymatic hydrolysis residual solids (EHRS), a cellulosic ethanol byproduct, were investigated as a bulking...
THE OPTIMIZATION OF PLUSH YARNS BULKING PROCESS
Directory of Open Access Journals (Sweden)
VINEREANU Adam
2014-05-01
Full Text Available This paper presents the experiments that were conducted on the installation of continuous bulking and thermofixing “SUPERBA” type TVP-2S for optimization of the plush yarns bulking process. There were considered plush yarns Nm 6.5/2, made of the fibrous blend of 50% indigenous wool sort 41 and 50% PES. In the first stage, it performs a thermal treatment with a turboprevaporizer at a temperature lower than thermofixing temperature, at atmospheric pressure, such that the plush yarns - deposed in a freely state on a belt conveyor - are uniformly bulking and contracting. It was followed the mathematical modeling procedure, working with a factorial program, rotatable central composite type, and two independent variables. After analyzing the parameters that have a direct influence on the bulking degree, there were selected the pre-vaporization temperature (coded x1,oC and the velocity of belt inside pre-vaporizer (coded x 2, m/min. As for the dependent variable, it was chosen the plush yarn diameter (coded y, mm. There were found the coordinates of the optimal point, and then this pair of values was verified in practice. These coordinates are: x1optim= 90oC and x 2optim= 6.5 m/min. The conclusion is that the goal was accomplished: it was obtained a good cover degree f or double-plush carpets by reducing the number of tufts per unit surface.
Characteristics of bulk liquid undercooling and crystallization ...
Indian Academy of Sciences (India)
157–161. c Indian Academy of Sciences. Characteristics of bulk liquid undercooling and crystallization behaviors of jet electrodeposition Ni–W–P alloy. J K YU. ∗. , Y H WANG, G Z XING, Q QIAO, B LIU, Z J CHU, C L LI and F YOU. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University,.
Characteristics of bulk liquid undercooling and crystallization ...
Indian Academy of Sciences (India)
Home; Journals; Bulletin of Materials Science; Volume 38; Issue 1. Characteristics of bulk liquid undercooling and crystallization behaviors of jet electrodeposition Ni–W–P alloy. J K Yu Y H Wang G Z Xing Q Qiao B Liu Z J Chu C L Li F You. Volume 38 Issue 1 February 2015 pp 157-161 ...
Failure by fracture in bulk metal forming
DEFF Research Database (Denmark)
Silva, C.M.A.; Alves, Luis M.; Nielsen, Chris Valentin
2015-01-01
This paper revisits formability in bulk metal forming in the light of fundamental concepts of plasticity,ductile damage and crack opening modes. It proposes a new test to appraise the accuracy, reliability and validity of fracture loci associated with crack opening by tension and out-of-plane shear...
Thermal bulk polymerization of cholesteryl acrylate
de Visser, A.C.; de Groot, K.; Feijen, Jan; Bantjes, A.
1971-01-01
The thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the
A large-scale biomass bulk terminal
Wu, M.R.
2012-01-01
This research explores the possibility of a large-scale bulk terminal in West Europe dedicated to handle solid and liquid biomass materials. Various issues regarding the conceptual design of such a terminal have been investigated and demonstrated in this research: the potential biomass materials
Bulk metamaterials: Design, fabrication and characterization
DEFF Research Database (Denmark)
Andryieuski, Andrei; Malureanu, Radu; Alabastri, Alessandro
2009-01-01
Bulk metamaterials claim a lot of attention worldwide. We report about our activity and advances in design, fabrication and characterization of metal-dielectric composites with three-dimensional lattices. The nomenclature of designs exhibiting negative index behaviour in the near infrared includes...
Polonium bulk and surface vibrational dynamics
Energy Technology Data Exchange (ETDEWEB)
Tigrine, Rachid; Bourahla, Boualem [Laboratoire de Physique PEC UMR 6087, Universite du Maine, Le Mans (France); Laboratoire de Physique et Chimie Quantique, Universite de Tizi Ouzou (Algeria); Khater, Antoine
2009-07-15
Calculations are presented for the bulk phonons and for surface Rayleigh phonons and resonances for Polonium, the only element known to form in the simple cubic lattice. The static stability of this lattice has been confirmed recently by ab initio simulations which yield two bulk elastic constants, c{sub 11} and c{sub 12}. Constitutive equations are derived for the isotropic cubic lattice based upon the Fuchs's method. This permits effectively a numerical evaluation of central potential force constants for Polonium from the ab initio results. Numerical calculations are then made for the material vibration dynamics in the force constant model with the use of the matching method. The numerical applications yield for Polonium the bulk phonon branches along[100],[110], and [111], and the Rayleigh phonons and surface resonances along the[010] direction in an unreconstructed (001) surface. The local vibration densities of states are calculated for bulk and surface sites for this element. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Modelling ventilated bulk storage of agromaterials
Grubben, N.L.M.; Keesman, K.J.
2015-01-01
Storage of season-dependent agro-materials is a key process in providing food, feed and biomass throughout the whole year. We review the state of the art in physical modelling, simulation and control of ventilated bulk storage facilities, and in particular the storage of potatoes, from a
Teaching Advanced SQL Skills: Text Bulk Loading
Olsen, David; Hauser, Karina
2007-01-01
Studies show that advanced database skills are important for students to be prepared for today's highly competitive job market. A common task for database administrators is to insert a large amount of data into a database. This paper illustrates how an up-to-date, advanced database topic, namely bulk insert, can be incorporated into a database…
Transformation kinetics for surface and bulk nucleation
Energy Technology Data Exchange (ETDEWEB)
Villa, Elena, E-mail: elena.villa@unimi.it [University of Milan, Department of Mathematics, via Saldini 50, 20133 Milano (Italy); Rios, Paulo R., E-mail: prrios@metal.eeimvr.uff.br [Universidade Federal Fluminense, Escola de Engenharia Industrial Metalurgica de Volta Redonda, Av. dos Trabalhadores 420, 27255-125 Volta Redonda, RJ (Brazil)] [RWTH Aachen University, Institut fuer Metallkunde und Metallphysik, D-52056 Aachen (Germany)
2010-04-15
A rigorous mathematical approach based on the causal cone and stochastic geometry concepts is used to derive new exact expressions for transformation kinetics theory. General expressions for the mean volume density and the volume fraction are derived for both surface and bulk nucleation in a general Borel subset of R{sup 3}. In practice, probably any specimen shape of engineering interest is going to be a Borel set. An expression is also derived for the important case of polyhedral shape, in which surface nucleation may take place on the faces, edges and vertices of the polyhedron as well as within the bulk. Moreover, explicit expressions are given for surface and bulk nucleation for three specific shapes of engineering relevance: two parallel planes, an infinitely long cylinder and a sphere. Superposition is explained in detail and it permits the treatment of situations in which surface and bulk nucleation take place simultaneously. The new exact expressions presented here result in a significant increase in the number of exactly solvable cases available to formal kinetics.
Scientific computing on bulk synchronous parallel architectures
Bisseling, R.H.; McColl, W.F.
1993-01-01
Bulk synchronous parallel architectures oer the prospect of achieving both scalable parallel performance and architecture independent parallel software. They provide a robust model on which to base the future development of general purpose parallel computing systems. In this paper, we theoretically
Radiopacity of bulk fill flowable resin composite materials | Yildirim ...
African Journals Online (AJOL)
Objectives: The purpose of this study was to evaluate the radiopacity of currently marketed bulk fill flowable dental composite materials (Beautifil Bulk Flowable, SDR Flow, Filtek Bulk Fill Flow, and x‑tra Base Bulk Fill). Materials and Methods: Six specimens of each material with a thickness of 1 mm were prepared, and ...
The Ideal Convergence of Strongly of Γ2 in p-Metric Spaces Defined by Modulus
Directory of Open Access Journals (Sweden)
N. Subramanian
2014-01-01
Full Text Available The aim of this paper is to introduce and study a new concept of the Γ2 space via ideal convergence defined by modulus and also some topological properties of the resulting sequence spaces were examined.
Yang, Wang; Dang, Xinkai; Yang, Jian; Mo, Jianlin
2017-09-01
Because sampling the surface soil appears loose and fracture of soil easily, the elastic modulus of the soil in the tillage layer was difficulty in measuring directly by physical tests. The dynamic simulation model of the cone-air-soil system was established. The multi-material ALE (Arbitrary Lagrangian-Eulerian) fluid-structure interaction method was used in the model. Based on the model, the elastic modulus of the soil was reversed. Meanwhile, the reverse elastic modulus was physically verified by the triaxial test. The results show that the inverse method is feasible. The error is 0.65% compared with the soil elastic modulus obtained by triaxial test. The numerical simulation model of cone-air-soil system has higher precision.
Wind Diffusivity Current, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Modulus
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality Ekman current (in zonal, meridional, and modulus sets) and Ekman upwelling data. This data begins with wind velocity...
Bulk sulfur (S) deposition in China
Liu, Lei; Zhang, Xiuying; Wang, Shanqian; Zhang, Wuting; Lu, Xuehe
2016-06-01
A systematic dataset of an observation network on a national scale has been organized to investigate the spatial distribution of bulk sulfur (S) deposition (Sdep) throughout China during 2000-2013, representing by far the most detailed data set to track the bulk sulfur deposition throughout China since 2000. Such a dataset is needed for ecosystem studies and for developing emission control policies. Bulk Sdep values showed great variations, ranging from 2.17 to 70.55 kg ha-1 y-1, with an average of 22.99 kg ha-1 y-1. The average rate of bulk Sdep located in East Coastal region (35.97 kg ha-1 y-1), Middle Yangtze region (57.90 kg ha-1 y-1), Middle Yellow River region (23.42 kg ha-1 y-1), North Coastal region (42.19 kg ha-1 y-1), Northeast region (34.28 kg ha-1 y-1), South Coastal region (36.97 kg S ha-1 y-1), Southwest region (33.85 kg ha-1 y-1) was 4.50, 7.24, 2.93, 5.28, 4.29, 4.63 and 4.24 times than that in Northwest region (7.99 kg ha-1 y-1). Bulk Sdep over China was mainly from fossil fuel combustion (76.96%), biomass burning (7.64%), crust (6.22%), aged sea salt (5.48%) and agriculture (3.68%). A systematic observation network on a national scale should be established to conduct a long-term monitoring atmospheric Sdep (including wet and dry deposition), based on exiting ecological stations administrated by different departments in China.
Zheng, Y. P.; Choi, A. P. C.; Ling, H. Y.; Huang, Y. P.
2009-04-01
Indentation is commonly used to determine the mechanical properties of different kinds of biological tissues and engineering materials. With the force-deformation data obtained from an indentation test, Young's modulus of the tissue can be calculated using a linear elastic indentation model with a known Poisson's ratio. A novel method for simultaneous estimation of Young's modulus and Poisson's ratio of the tissue using a single indentation was proposed in this study. Finite element (FE) analysis using 3D models was first used to establish the relationship between Poisson's ratio and the deformation-dependent indentation stiffness for different aspect ratios (indentor radius/tissue original thickness) in the indentation test. From the FE results, it was found that the deformation-dependent indentation stiffness linearly increased with the deformation. Poisson's ratio could be extracted based on the deformation-dependent indentation stiffness obtained from the force-deformation data. Young's modulus was then further calculated with the estimated Poisson's ratio. The feasibility of this method was demonstrated in virtue of using the indentation models with different material properties in the FE analysis. The numerical results showed that the percentage errors of the estimated Poisson's ratios and the corresponding Young's moduli ranged from -1.7% to -3.2% and 3.0% to 7.2%, respectively, with the aspect ratio (indentor radius/tissue thickness) larger than 1. It is expected that this novel method can be potentially used for quantitative assessment of various kinds of engineering materials and biological tissues, such as articular cartilage.
Zhu, Dongming; Miller, Robert A.
1999-01-01
Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may he encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1. 15 W/m-K, 1. 19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990C, 1100C, and 1320C. respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications.
Static versus dynamic gerbil tympanic membrane elasticity: derivation of the complex modulus.
Aernouts, Jef; Dirckx, Joris J J
2012-07-01
An accurate estimation of tympanic membrane stiffness is important for realistic modelling of middle ear mechanics. Tympanic membrane stiffness has been investigated extensively under either quasi-static or dynamic loading conditions. It is known that biological tissues are sensitive to strain rate. Therefore, in this work, the mechanical behaviour of the tympanic membrane was studied under both quasi-static and dynamic loading conditions. Experiments were performed on the pars tensa of four gerbil tympanic membranes. A custom-built indentation apparatus was used to perform in situ tissue indentations and testing was done applying both quasi-static and dynamic sinusoidal indentations up to 8.2 Hz. The unloaded shape of the tympanic membrane was measured and used to create specimen-specific finite element models to simulate the experiments. The frequency dependent Young's modulus of each specimen was then estimated by an inverse analysis in which the error between experimental and simulated indentation data was optimised for each indentation frequency separately. Using an 8 μm central region thickness, we found Young's moduli between 71 and 106 MPa (n = 4) at 0.2 Hz indentation frequency. A standard linear viscoelastic model and a viscoelastic model with a continuous relaxation spectrum were used to derive a complex modulus in the frequency domain. Due to experimental limitations, the indentation frequency upper limit was 8.2 Hz. The average relative modulus increase in this domain was 14% and the increase was the strongest below 6 Hz.
Modeling the Elastic Modulus of 2D Woven CVI SiC Composites
Morscher, Gregory N.
2006-01-01
The use of fiber, interphase, CVI SiC minicomposites as structural elements for 2D-woven SiC fiber reinforced chemically vapor infiltrated (CVI) SiC matrix composites is demonstrated to be a viable approach to model the elastic modulus of these composite systems when tensile loaded in an orthogonal direction. The 0deg (loading direction) and 90deg (perpendicular to loading direction) oriented minicomposites as well as the open porosity and excess SiC associated with CVI SiC composites were all modeled as parallel elements using simple Rule of Mixtures techniques. Excellent agreement for a variety of 2D woven Hi-Nicalon(TradeMark) fiber-reinforced and Sylramic-iBN reinforced CVI SiC matrix composites that differed in numbers of plies, constituent content, thickness, density, and number of woven tows in either direction (i.e, balanced weaves versus unbalanced weaves) was achieved. It was found that elastic modulus was not only dependent on constituent content, but also the degree to which 90deg minicomposites carried load. This depended on the degree of interaction between 90deg and 0deg minicomposites which was quantified to some extent by composite density. The relationships developed here for elastic modulus only necessitated the knowledge of the fractional contents of fiber, interphase and CVI SiC as well as the tow size and shape. It was concluded that such relationships are fairly robust for orthogonally loaded 2D woven CVI SiC composite system and can be implemented by ceramic matrix composite component modelers and designers for modeling the local stiffness in simple or complex parts fabricated with variable constituent contents.
Mechanical properties of low modulus beta titanium alloys designed from the electronic approach.
Laheurte, P; Prima, F; Eberhardt, A; Gloriant, T; Wary, M; Patoor, E
2010-11-01
Titanium alloys dedicated to biomedical applications may display both clinical and mechanical biocompatibility. Based on nontoxic elements such as Ti, Zr, Nb, Ta, they should combine high mechanical resistance with a low elastic modulus close to the bone elasticity (E=20 GPa) to significantly improve bone remodelling and osseointegration processes. These elastic properties can be reached using both lowering of the intrinsic modulus by specific chemical alloying and superelasticity effects associated with a stress-induced phase transformation from the BCC metastable beta phase to the orthorhombic alpha(″) martensite. It is shown that the stability of the beta phase can be triggered using a chemical formulation strategy based on the electronic design method initially developed by Morinaga. This method is based on the calculation of two electronic parameters respectively called the bond order (B(o)) and the d orbital level (M(d)) for each alloy. By this method, two titanium alloys with various tantalum contents, Ti-29Nb-11Ta-5Zr and Ti-29Nb-6Ta-5Zr (wt%) were prepared. In this paper, the effect of the tantalum content on the elastic modulus/yield strength balance has been investigated and discussed regarding the deformation modes. The martensitic transformation beta-->alpha(″) has been observed on Ti-29Nb-6Ta-5Zr in contrast to Ti-29Nb-11Ta-5Zr highlighting the chemical influence of the Ta element on the initial beta phase stability. A formulation strategy is discussed regarding the as-mentioned electronic parameters. Respective influence of cold rolling and flash thermal treatments (in the isothermal omega phase precipitation domain) on the tensile properties has been investigated. (c) 2010 Elsevier Ltd. All rights reserved.
Elastic modulus and collagen organization of the rabbit cornea: epithelium to endothelium.
Thomasy, Sara M; Raghunathan, Vijay Krishna; Winkler, Moritz; Reilly, Christopher M; Sadeli, Adeline R; Russell, Paul; Jester, James V; Murphy, Christopher J
2014-02-01
The rabbit is commonly used to evaluate new corneal prosthetics and study corneal wound healing. Knowledge of the stiffness of the rabbit cornea would better inform the design and fabrication of keratoprosthetics and substrates with relevant mechanical properties for in vitro investigations of corneal cellular behavior. This study determined the elastic modulus of the rabbit corneal epithelium, anterior basement membrane (ABM), anterior and posterior stroma, Descemet's membrane (DM) and endothelium using atomic force microscopy (AFM). In addition, three-dimensional collagen fiber organization of the rabbit cornea was determined using nonlinear optical high-resolution macroscopy. The elastic modulus as determined by AFM for each corneal layer was: epithelium, 0.57 ± 0.29 kPa (mean ± SD); ABM, 4.5 ± 1.2 kPa, anterior stroma, 1.1 ± 0.6 kPa; posterior stroma, 0.38 ± 0.22 kPa; DM, 11.7 ± 7.4 kPa; and endothelium, 4.1 ± 1.7 kPa. The biophysical properties, including the elastic modulus, are unique for each layer of the rabbit cornea and are dramatically softer in comparison to the corresponding regions of the human cornea. Collagen fiber organization is also dramatically different between the two species, with markedly less intertwining observed in the rabbit vs. human cornea. Given that the substratum stiffness considerably alters the corneal cell behavior, keratoprosthetics that incorporate mechanical properties simulating the native human cornea may not elicit optimal cellular performance in rabbit corneas that have dramatically different elastic moduli. These data should allow for the design of substrates that better mimic the biomechanical properties of the corneal cellular environment. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Lam, Cherry Wing Yu; Ikeda, Shinya
2017-05-01
Texture modifying abilities of whey protein microparticles are expected to be dependent on pH during heat-induced aggregation of whey protein in the microparticulation process. Therefore, whey protein microparticles were prepared at either pH 5.5 or 6.8 and their effects on small and large deformation properties of gellan gels containing whey protein microparticles as fillers were investigated. The majority of whey protein microparticles had diameters around 2 μm. Atomic force microscopy images showed that whey protein microparticles prepared at pH 6.8 partially collapsed and flatted by air-drying, while those prepared at pH 5.5 did not. The Young's modulus of filled gels adjusted to pH 5.5 decreased by the addition of whey protein microparticles, while those of filled gels adjusted to pH 6.8 increased with increasing volume fraction of filler particles. These results suggest that filler particles were weakly bonded to gel matrices at pH 5.5 but strongly at pH 6.8. Whey protein microparticles prepared at pH 5.5 showed more enhanced increases in the Young's modulus than those prepared at pH 6.8 at volume fractions between 0.2 and 0.4, indicating that microparticles prepared at pH 5.5 were mechanically stronger. The fracture stress of filled gels showed trends somewhat similar to those of the Young's modulus, while their fracture strains decreased by the addition of whey protein microparticles in all examined conditions, indicating that the primary effect of these filler particles was to enhance the brittleness of filled gels. © 2017 Institute of Food Technologists®.
Shear and longitudinal modulus of elasticity in Corymbia citriodora round timber beams
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André Luiz Zangiácomo
2013-07-01
Full Text Available This study aimed to evaluate, with the support of the three points static bending test, led nondestructively, the values of the shear (G and longitudinal (E modulus of elasticity in Corymbia citriodora structural round timber beams in order to verify the validity of the G=E/20 relationship established by the Brazilian standard ABNT NBR 7190:1997 (Design of Wood Structures. The specimens tested (20 have an average length of 750 cm, diameter of 30 cm, moisture content of 12% and 5% of average taper. There were two bending tests per element, with differences in the distances between supports. In the first trial, we used the L/D ratio between the length (L and diameter (d of the pieces equal to twenty-four, while the second was conducted in sequence, with L/d equal to fifteen. The elasticity modulus were obtained according to the successive use of the equation of Timoshenko’s beam theory, which takes into account the influence of the shear efforts to determine displacements. The results between the shear and longitudinal modulus of elasticity were related by the least squares method, the relationship G=E/56 was found, which demonstrates divergent results with the Brazilian standard for the structural round timber investigated.
Mehrab Madhoushi; Soheila Daneshvar
2014-01-01
The aim of this paper was to evaluate relationship between dynamic modulus of elasticity (MOEd) in healthy standing trees of Populus deltoides and static modulus of elasticity (MOEs) of sawn lumber from the same standing trees, using nondestructive stress wave testing (NDT). For this purpose, NDT stress wave technique was used. The study was performed on 10 healthy standing trees of Populus deltoides. The diameter of trees at the breast height was selected at two categories, namely 25-30 cm a...
Graphical Analysis of Static and Dynamic Elastic Modulus of Shaving Sheet
Chunhui Liao; Houjiang Zhang; Lujing Zhou; Haicheng Yan
2013-01-01
The traditional measurement method of thin wood-based panel’s elastic modulus is carried out on the test piece for three-point or four-point bending static deformation test, the determination process is complex, time consuming, and makes damage to specimen. Use materials mechanics quick measuring instrument of sheet board wood, which is self-developed and based on the principle of cantilever’s free vibration and cantilever bending to test three standards of thin wood-based panels&...
Anisotropy in the helicity modulus of a three-dimensional XY-model: application to YBCO
Energy Technology Data Exchange (ETDEWEB)
Mitrovic, Bozidar; Bose, Shyamal K; Samokhin, Kirill [Physics Department, Brock University, St Catharines, ON L2S 3A1 (Canada)
2003-04-09
We present a Monte Carlo study of the helicity moduli of an anisotropic classical three-dimensional XY-model of YBCO in the superconducting state. It is found that both the ab-plane and the c-axis helicity moduli, which are proportional to the inverse square of the corresponding magnetic field penetration depth, vary linearly with temperature at low temperatures. The result for the c-axis helicity modulus is in disagreement with the experiments on high-quality samples of YBCO. Thus we conclude that purely classical phase fluctuations of the superconducting order parameter cannot account for the observed c-axis electrodynamics of YBCO.
On the Space of Functions with Growths Tempered by a Modulus of Continuity and Its Applications
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Józef Banaś
2013-01-01
Full Text Available We are going to study the space of real functions defined on a bounded metric space and having growths tempered by a modulus of continuity. We prove also a sufficient condition for the relative compactness in the mentioned function space. Using that condition and the classical Schauder fixed point theorem, we show the existence theorem for some quadratic integral equations of Fredholm type in the space of functions satisfying the Hölder condition. An example illustrating the mentioned existence result is also included.
arXiv A Simple No-Scale Model of Modulus Fixing and Inflation
Ellis, John; Romano, Antonio Enea; Zapata, Oscar
We construct a no-scale model of inflation with a single modulus whose real and imaginary parts are fixed by simple power-law corrections to the no-scale K{\\" a}hler potential. Assuming an uplift of the minimum of the effective potential, the model yields a suitable number of e-folds of expansion and values of the tilt in the scalar cosmological density perturbations and of the ratio of tensor and scalar perturbations that are compatible with measurements of the cosmic microwave background radiation.
DEFF Research Database (Denmark)
Hecksher, Tina; Jakobsen, Bo; Dyre, J. C.
2014-01-01
scale are covered. The singly hydrogen-bonded monohydroxy alcohols were chosen because they display significant, but surprisingly poorly understood effects of intermolecular association. Based on the present shear study, one can apply theoretical concepts of polymer science to understand the anomalous...... physical behavior of a wide range of hydrogen-bonded liquids.......Liquids composed of small-molecule monohydroxy alcohols are demonstrated to display rheological behavior typical for oligomeric chains. This observation was made possible by rheological experiments in which more than seven decades in frequency and more than five decades on the mechanical modulus...
Elastic Metamaterials with Simultaneously Negative Effective Shear Modulus and Mass Density
Wu, Ying
2011-09-02
We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids.
Method for in-situ nondestructive measurement of Young's modulus of plate structures
Huang, Jerry Qixin (Inventor); Perez, Robert J. (Inventor); DeLangis, Leo M. (Inventor)
2003-01-01
A method for determining stiffness of a composite laminate plate entails disposing a device for generating an acoustical pulse against a surface of the plate and disposing a detecting device against the same surface spaced a known distance from the pulse-generating device, and using the pulse-generating device to emit a pulse so as to create an extensional wave in the plate. The detecting device is used to determine a time of flight of the wave over the known distance, and the wave velocity is calculated. A Young's modulus of the plate is determined based on the wave velocity. Methods for both anisotropic and quasi-isotropic laminates are disclosed.
Measurement of elastic modulus and ultrasonic wave velocity by piezoelectric resonator
Erhart, Jiří
2015-01-01
A piezoelectric ceramic resonator is used for the ‘electrical’ measurement of elastic properties, i.e. Young’s modulus and ultrasonic wave velocity in metallic materials. Piezoelectric response is precisely calculated for the piezoelectric ceramic ring fixed at the end of a metallic rod. The piezoelectric ring serves as both an actuator as well as a sensor. The experimental setup and method of measurement using higher overtones is explained in detail and practically demonstrated for a set of different metallic materials. Young’s moduli and ultrasonic wave velocities are measured within 3% relative error. The presented method is suitable for an advanced engineering class or physics laboratory training.
Lateral Earth Pressure at Rest and Shear Modulus Measurements on Hanford Sludge Simulants
Energy Technology Data Exchange (ETDEWEB)
Wells, Beric E.; Jenks, Jeromy WJ; Boeringa, Gregory K.; Bauman, Nathan N.; Guzman, Anthony D.; Arduino, P.; Keller, P. J.
2010-09-30
This report describes the equipment, techniques, and results of lateral earth pressure at rest and shear modulus measurements on kaolin clay as well as two chemical sludge simulants. The testing was performed in support of the problem of hydrogen gas retention and release encountered in the double- shell tanks (DSTs) at the Hanford Site near Richland, Washington. Wastes from single-shell tanks (SSTs) are being transferred to double-shell tanks (DSTs) for safety reasons (some SSTs are leaking or are in danger of leaking), but the available DST space is limited.
Young's modulus and indirect morphological analysis of Bi2Se3 nanoribbons by resonance measurements.
Kosmaca, J; Jasulaneca, L; Meija, R; Andzane, J; Romanova, M; Kunakova, G; Erts, D
2017-08-11
An electrostatically induced resonance behaviour of individual topological insulator Bi2Se3 nanoribbons grown by a catalyst free vapour-solid synthesis was studied in situ by scanning electron microscopy. It was demonstrated that the relation between the resonant frequencies of vibrations in orthogonal planes can be applied to distinguish the nanoribbons with rectangular cross-sections from the nanoribbons having step-like morphology (terraces). The average Young's modulus of the Bi2Se3 nanoribbons with rectangular cross-sections was found to be 44 ± 4 GPa.
Wu, Jingjing; Liu, Wei; Liu, Zhengjun; Liu, Shutian
2015-10-20
We analyze and present an attack scheme of the asymmetric optical cryptosystem proposed recently based on coherent superposition and equal modulus decomposition [Opt. Lett.40, 475 (2015)OPLEDP0146-959210.1364/OL.40.000475]. We prove that the attacker can recover the original image with the ciphertext and public keys through the amplitude-phase retrieval algorithm by using two constraints. One constraint of the amplitude-phase retrieval algorithm is the public key and the other is obtained through the analysis of the cryptosystem. The simulation results demonstrate the feasibility of the attack method.
Methods for calculating phase angle from measured whole body bioimpedance modulus
Nordbotten, Bernt J.; Martinsen, Ørjan G.; Grimnes, Sverre
2010-04-01
Assuming the Cole equation we have developed a method to calculate the Cole parameters (R0, R∞, α, τZ) and the phase angle from four frequency measurements of impedance modulus values. The values obtained compare well with impedance measurements obtained using the Solatron 1294/1260 as obtained when making whole body measurements on five persons. We have also performed calculations using an algorithm based on the Kramers-Kronig approach. The results which are presented show that it is possible to obtain complete body impedance data combining relatively simple measurements with advanced calculation using a laptop. This extends the potential of portable equipment, since the measurements will require less instrumentation.
Effect of Variations in Micropatterns and Surface Modulus on Marine Fouling of Engineering Polymers.
Brzozowska, Agata Maria; Maassen, Stan; Goh Zhi Rong, Rubayn; Benke, Peter Imre; Lim, Chin-Sing; Marzinelli, Ezequiel M; Jańczewski, Dominik; Teo, Serena Lay-Ming; Vancso, G Julius
2017-05-24
We report on the marine fouling and fouling release effects caused by variations of surface mechanical properties and microtopography of engineering polymers. Polymeric materials were covered with hierarchical micromolded topographical patterns inspired by the shell of the marine decapod crab Myomenippe hardwickii. These micropatterned surfaces were deployed in field static immersion tests. PDMS, polyurethane, and PMMA surfaces with higher elastic modulus and hardness were found to accumulate more fouling and exhibited poor fouling release properties. The results indicate interplay between surface mechanical properties and microtopography on antifouling performance.
Chacón, Enrique; Tarazona, Pedro; Bresme, Fernando
2015-07-01
We present a new computational approach to quantify the area per lipid and the area compressibility modulus of biological membranes. Our method relies on the analysis of the membrane fluctuations using our recently introduced coupled undulatory (CU) mode [Tarazona et al., J. Chem. Phys. 139, 094902 (2013)], which provides excellent estimates of the bending modulus of model membranes. Unlike the projected area, widely used in computer simulations of membranes, the CU area is thermodynamically consistent. This new area definition makes it possible to accurately estimate the area of the undulating bilayer, and the area per lipid, by excluding any contributions related to the phospholipid protrusions. We find that the area per phospholipid and the area compressibility modulus features a negligible dependence with system size, making possible their computation using truly small bilayers, involving a few hundred lipids. The area compressibility modulus obtained from the analysis of the CU area fluctuations is fully consistent with the Hooke's law route. Unlike existing methods, our approach relies on a single simulation, and no a priori knowledge of the bending modulus is required. We illustrate our method by analyzing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers using the coarse grained MARTINI force-field. The area per lipid and area compressibility modulus obtained with our method and the MARTINI forcefield are consistent with previous studies of these bilayers.
Energy Technology Data Exchange (ETDEWEB)
Chacón, Enrique, E-mail: echacon@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Tarazona, Pedro, E-mail: pedro.tarazona@uam.es [Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Bresme, Fernando, E-mail: f.bresme@imperial.ac.uk [Department of Chemistry, Imperial College London, SW7 2AZ London (United Kingdom)
2015-07-21
We present a new computational approach to quantify the area per lipid and the area compressibility modulus of biological membranes. Our method relies on the analysis of the membrane fluctuations using our recently introduced coupled undulatory (CU) mode [Tarazona et al., J. Chem. Phys. 139, 094902 (2013)], which provides excellent estimates of the bending modulus of model membranes. Unlike the projected area, widely used in computer simulations of membranes, the CU area is thermodynamically consistent. This new area definition makes it possible to accurately estimate the area of the undulating bilayer, and the area per lipid, by excluding any contributions related to the phospholipid protrusions. We find that the area per phospholipid and the area compressibility modulus features a negligible dependence with system size, making possible their computation using truly small bilayers, involving a few hundred lipids. The area compressibility modulus obtained from the analysis of the CU area fluctuations is fully consistent with the Hooke’s law route. Unlike existing methods, our approach relies on a single simulation, and no a priori knowledge of the bending modulus is required. We illustrate our method by analyzing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers using the coarse grained MARTINI force-field. The area per lipid and area compressibility modulus obtained with our method and the MARTINI forcefield are consistent with previous studies of these bilayers.
Hot Embossing of Zr-Based Bulk Metallic Glass Micropart Using Stacked Silicon Dies
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Zhijing Zhu
2015-01-01
Full Text Available We demonstrated hot embossing of Zr65Cu17.5Ni10Al7.5 bulk metallic glass micropart using stacked silicon dies. Finite element simulation was carried out, suggesting that it could reduce the stress below 400 MPa in the silicon dies and enhance the durability of the brittle silicon dies when using varying load mode (100 N for 60 s and then 400 N for 60 s compared with using constant load mode (200 N for 120 s. A micropart with good appearance was fabricated under the varying load, and no silicon die failure was observed, in agreement with the simulation. The amorphous state of the micropart was confirmed by differential scanning calorimeter and X-ray diffraction, and the nanohardness and Young’s modulus were validated close to those of the as-cast BMG rods by nanoindentation tests. The results proved that it was feasible to adopt the varying load mode to fabricate three-dimensional Zr-based bulk metallic glass microparts by hot embossing process.
Tribological characterisation of Zr-based bulk metallic glass in simulated physiological media
Chen, Q.; Chan, K. C.; Liu, L.
2011-10-01
Due to their excellent wear resistant properties and high strength, as well as a low Young's modulus, Zr-based bulk metallic glasses (BMGs) are potentially suitable biomaterials for low-friction arthroplasty. The wear characteristics of the Zr60.14Cu22.31Fe4.85Al9.7Ag3 bulk amorphous alloy against ultra-high-molecular-weight polyethylene (UHMWPE) compared to a CoCrMo/UHMWPE combination were investigated in two different wear screening test devices, reciprocating and unidirectional. Hank's solution and sterile calf bovine serum were selected as the lubricant fluid media. It was found that different fluid media had insignificant effect on polyethylene wear against BMG counterfaces. The wear behaviour obtained on both test devices demonstrated that Zr-based BMG achieved UHMWPE counterface wear rates superior to conventional cast CoCrMo alloy, where the wear rate of UHMWPE is decreased by over 20 times. The tribological performance of these joints is superior to that of conventional metal-on-polymer designs. Contact angle measurements suggested that the advantage of BMG over a CoCrMo alloy counterface is attributed to its highly hydrophilic surfaces.
Connecting point defect parameters with bulk properties to describe diffusion in solids
Chroneos, A.
2016-12-01
Diffusion is a fundamental process that can have an impact on numerous technological applications, such as nanoelectronics, nuclear materials, fuel cells, and batteries, whereas its understanding is important across scientific fields including materials science and geophysics. In numerous systems, it is difficult to experimentally determine the diffusion properties over a range of temperatures and pressures. This gap can be bridged by the use of thermodynamic models that link point defect parameters to bulk properties, which are more easily accessible. The present review offers a discussion on the applicability of the cBΩ model, which assumes that the defect Gibbs energy is proportional to the isothermal bulk modulus and the mean volume per atom. This thermodynamic model was first introduced 40 years ago; however, consequent advances in computational modelling and experimental techniques have regenerated the interest of the community in using it to calculate diffusion properties, particularly under extreme conditions. This work examines recent characteristic examples, in which the model has been employed in semiconductor and nuclear materials. Finally, there is a discussion on future directions and systems that will possibly be the focus of studies in the decades to come.
Directory of Open Access Journals (Sweden)
Dimas Puja Permana
2016-12-01
Full Text Available Micoleakage comparison of bulk-fillcomposite beetwen oblique incremental and bulk placement techniques. Resin composite bulk-fill was a new type of resin composite that speed up application process of composite. The concept of bulk-fill composite allows composite to fill at a depth of 4 mm and minimizes polymerization shrinkage. This study aims to determine the comparison of placement techniques (oblique incremental/bulk of bulk-fill composite on microleakage in class I preparations. Thirty two human maxillary premolar were stored in distilled water, then Class I preparations were made with the depth of the cavity which was 4 mm (3 x 3 x 4. The teeth were randomly divided into two groups, group 1 uses oblique incremental placement technique and group 2 with bulk placement technique. Samples were stored in an incubator at a temperature of 37 °C for 24 hours, then it was thermocycled manually, 100 cycles at temperature between 5 °C and 55 °C. Microleakage was measured using a digital microscope with a 100 X magnification in millimeters using a microscope micrometer calibration ruler with 0,1 mm level of accuracy after immersion in 0,3% methylene blue and sectioned using separating disc. The result of this study revealed that in group 1 microleakage range was 1.0 mm - 2.7 mm with an average 1.625 mm, and in group 2 microleakage range was 3.6 mm - 4.0 mm with an average of 3.763 mm. The data were analyzed using T-test. The analysis showed a significant difference between two groups (p <0.05. The conclusion of this study was bulk-fill composite in class I cavities with oblique incremental placement technique produces less microleakage than bulk placement technique. ABSTRAK Resin komposit bulk-fill adalah resin komposit yang dirancang untuk mempercepat proses aplikasi resin komposit. Konsep bulk-fill memungkinkan resin komposit ditumpat sekaligus 4 mm dan mengalami pengerutan polimerisasi minimal. Penelitian ini bertujuan mengetahui efek teknik
Transient Thermal Tensile Behaviour of Novel Pitch-Based Ultra-High Modulus CFRP Tendons
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Giovanni Pietro Terrasi
2016-12-01
Full Text Available A novel ultra-high modulus carbon fibre reinforced polymer (CFRP prestressing tendon made from coal tar pitch-based carbon fibres was characterized in terms of high temperature tensile strength (up to 570 °C with a series of transient thermal and steady state temperature tensile tests. Digital image correlation was used to capture the high temperature strain development during thermal and mechanical loading. Complementary thermogravimetric (TGA and dynamic mechanical thermal (DMTA experiments were performed on the tendons to elucidate their high temperature thermal and mechanical behaviour. The novel CFRP tendons investigated in the present study showed an ambient temperature design tensile strength of 1400 MPa. Their failure temperature at a sustained prestress level of 50% of the design tensile strength was 409 °C, which is higher than the failure temperature of most fibre reinforced polymer rebars used in civil engineering applications at similar utilisation levels. This high-temperature tensile strength shows that there is potential to use the novel high modulus CFRP tendons in CFRP pretensioned concrete elements for building applications that fulfill the fire resistance criteria typically applied within the construction industry.
On the relationship between the plateau modulus and the threshold frequency in peptide gels.
Rizzi, L G
2017-12-28
Relations between static and dynamic viscoelastic responses in gels can be very elucidating and may provide useful tools to study the behavior of bio-materials such as protein hydrogels. An important example comes from the viscoelasticity of semisolid gel-like materials, which is characterized by two regimes: a low-frequency regime, where the storage modulus G'(ω) displays a constant value Geq, and a high-frequency power-law stiffening regime, where G'(ω) ∼ ωn. Recently, by considering Monte Carlo simulations to study the formation of peptides networks, we found an intriguing and somewhat related power-law relationship between the plateau modulus and the threshold frequency, i.e., Geq∼(ω*)Δ with Δ = 2/3. Here we present a simple theoretical approach to describe that relationship and test its validity by using experimental data from a β-lactoglobulin gel. We show that our approach can be used even in the coarsening regime where the fractal model fails. Remarkably, the very same exponent Δ is found to describe the experimental data.
[Estimation of modulus of elasticity of Eucalyptus pellita wood by near infrared spectroscopy].
Zhao, Rong-jun; Huo, Xiao-mei; Zhang, Li
2009-09-01
In the present study, the rapid prediction of wood modulus of elasticity (MOE) of Eucalyptus pellita by near infrared (NIR) spectroscopy is described. Fast Fourier transform (FFT) and conventional mechanical testing methods were used to measure modulus of elasticity of small clear wood samples of Eucalyptus pellita. After collecting the near-infrared reflectance spectra of each sample from radial and tangential faces, the NIR spectra were preprocessed with the second-derivative methods, and regression models were built between 410 to 2 480 nm. The calibration models were established using two thirds of whole samples with the partial least squares method, and validation models were developed on an independent set (one third of whole samples). The analysis results showed that high correlation coefficients were obtained between the laboratory-determined MOE values and NIR prediction values of Eucalyptus pellita. The correlation coefficients of prediction model for MOE were 0.93 and 0.81, and RPD were 2.70 and 1.71. NIR analysis technique can realize the rapid prediction of the MOE of small clear wood samples of Eucalyptus pellita.
Modulus of elasticity of randomly and aligned polymeric scaffolds with fiber size dependency.
Wang, Jun; Yuan, Bo; Han, Ray P S
2017-09-20
The stiffness of a nano-fibrous scaffold is generally enhanced due to the size-dependency of the thin nanofibers contained in the scaffold. We proposed a model that incorporates size-dependency of single nanofibers to predict the scaffold effective modulus, in which the fibers' random or orientation distribution are considered. In the model the fiber segments between rigid fiber-fiber bonds can be stretching, shearing and bending. Using deformation energy equilibrium between sum of individual fibers and the plate of nano-fibrous scaffold, the scaffold effective modulus was derived explicitly. The model was verified via finite element analysis (FEA) and published experimental results. The parametric studies revealed that the fiber diameter is the dominant parameter to stiffen the scaffold beyond the fiber density and fiber aspect ratio when the fiber diameter is reduced below the onset value of size-dependencies. As a result, the scaffold stiffness can maintain its higher value and lower decrease rate because of the size-dependency with a decreasing diameter of the nanofiber as a result of biodegradation. This inspires the idea of selecting nanofibers near the onset value of size-dependency to obtain a controlled tuning of the scaffold stiffness in the design of novel nano-fibrous scaffolds. Copyright © 2017 Elsevier Ltd. All rights reserved.
Estimation of Elastic Modulus of Intact Rocks by Artificial Neural Network
Ocak, Ibrahim; Seker, Sadi Evren
2012-11-01
The modulus of elasticity of intact rock ( E i) is an important rock property that is used as an input parameter in the design stage of engineering projects such as dams, slopes, foundations, tunnel constructions and mining excavations. However, it is sometimes difficult to determine the modulus of elasticity in laboratory tests because high-quality cores are required. For this reason, various methods for predicting E i have been popular research topics in recently published literature. In this study, the relationships between the uniaxial compressive strength, unit weight ( γ) and E i for different types of rocks were analyzed, employing an artificial neural network and 195 data obtained from laboratory tests carried out on cores obtained from drilling holes within the area of three metro lines in Istanbul, Turkey. Software was developed in Java language using Weka class libraries for the study. To determine the prediction capacity of the proposed technique, the root-mean-square error and the root relative squared error indices were calculated as 0.191 and 92.587, respectively. Both coefficients indicate that the prediction capacity of the study is high for practical use.
Visco-elasticity of bottlebrush polymer melts: Pushing the lower limit of the entanglement modulus
Daniel, William; Burdynska, Joanna; Dobrynin, Andrey; Matyjaszewski, Krzysztof; Rubinstein, Michael; Sheiko, Sergei; Materials Interdisciplinary Research Team @ UNC Chapel Hill Team
2015-03-01
Without swelling in a solvent, it is challenging to obtain materials with a modulus below ca.105 Pa, which is dictated by chain entanglements. Here we analyze the densely grafted molecular brush architecture to create solvent-free neat polymer melts and elastomers with plateau moduli down to hundred Pa. Such materials are theorized to behave as linear chains with rescaled dimensions of the entanglement strand due to the increase in both width and persistence length of polymer bottlebrushes. This simple rescaling leads to a prediction that entanglement modulus decreases with the degree of polymerization (DP) of the sidechains to the -1.5 power. Experimental evidence gives a remarkably close power of -1.38 +/- 0.05 with moduli in the hundreds of Pascals for long sidechains with DP ≅100. The experimental data have been fit using a combination of the Rouse relaxation and double reputation models lending further evidence that bottlebrush polymer behave as linear polymers with large entanglement weights and longer persistence lengths. With the addition of crystallizable block it will be possible to control the crosslinking density and design ultrasoft shapememory materials for use in mechanically sensitive applications. NSF DMR-1407645, DMR-1122483.
El-Sayed, Somyia; Abel-Baset, Tarob; Elfadl, Azza Abou; Hassen, Arafa
2015-05-01
Nanosilica (NS) was synthesized by a sol-gel method and mixed with 0.98 polyvinyl alcohol (PVA)/0.02 polyaniline (PANI) in different amounts to produce nanocomposite films. High-resolution transmission electron microscopy (HR-TEM) revealed the average particle size of the NS to be ca. 15 nm. Scanning electron microscopy (SEM) showed that the NS was well-dispersed on the surface of the PVA/PNAI films. The Fourier transform infrared (FTIR) spectra of the samples showed a significant change in the intensity of the characteristic peak of the functional groups in the composite films with the amount of NS added. The absorbance and refractive index (n) of the composites were studied in the UV-vis range, and the optical energy band gap, Eg, and different optical parameters were calculated. The dielectric loss modulus, M″ and ac conductivity, σac, of the samples were studied within 300-425 K and 0.1 kHz-5 MHz, respectively. Two relaxation peaks were observed in the frequency dependence of the dielectric loss modulus, M″. The behavior of σac(f) for the composite films indicated that the conduction mechanism was correlated barrier hopping (CBH). The results of this work are discussed and compared with those of previous studies of similar composites.
Dielectric and modulus analysis of the photoabsorber Cu2SnS3
Lahlali, S.; Essaleh, L.; Belaqziz, M.; Chehouani, H.; Alimoussa, A.; Djessas, K.; Viallet, B.; Gauffier, J. L.; Cayez, S.
2017-12-01
Dielectric properties of the ternary semiconductor compound Cu2SnS3 is studied for the first time in the high temperature range from 300 °C to 440 °C with the frequency range 1 kHz to 1 MHz. The dielectric constant ε ‧ and dielectric loss tan (δ) were observed to increase with temperature and decrease rapidly with frequency to remains constant at high frequencies. The variation of the dielectric loss Ln (ε ") with L n (ω) was found to follow the empirical law, ε " = B ω m (T). The dielectric data were analyzed using complex electrical modulus M* at various temperatures. The activation energy responsible for the relaxation is estimated from the analysis of the modulus spectra. The value of the hopping barrier potential is estimated from the dielectric loss and compared with the value previously obtained from ac-conductivity. These results are critical for understanding the behavior of based polycrystalline family of Cu2SnS3 for absorber materials in solar-cells.
Analysis of the multistage cyclic loading test on resilient modulus value64
Directory of Open Access Journals (Sweden)
Sas Wojciech
2016-03-01
Full Text Available Analysis of the multistage cyclic loading test on resilient modulus value. Upon cyclic excitation of soil mass, two types of strain can be recognized, namely elastic and plastic one. Proper analysis of these two types of deformations can help engineers in designing more reliable structures. In this study, a multistage uniaxial cyclic loading in unconfined conditions was performed. Tests were performed in order to characterize strain response to repeated excitation. Soil sample under cyclic loading was recognized as exhibiting the symptoms of a plastic strain growth during the cyclic loading process with exponential manner, when compared to number of cycles. Soil in this study was reconstituted and compacted by using the Proctor method to simulate conditions similar to those affecting the road subbase. The soil was recognized as sandy clay. Results were analysed and a proposition of empirical formula for plastic strain calculation with the use of characteristic stress values was presented. The resilient modulus values were also calculated. The Mr value was within range from 45 to 105 MPa. The conclusions concerning the cyclically loaded soil in uniaxial conditions were presented.
The thermal conductivity of high modulus Zylon fibers between 400 mK and 4 K
Wikus, Patrick; Figueroa-Feliciano, Enectalí; Hertel, Scott A.; Leman, Steven W.; McCarthy, Kevin A.; Rutherford, John M.
2008-11-01
Zylon is a synthetic polyurethane polymer fiber featuring very high mechanical strength. Measurements of the thermal conductivity λZ(T) of high modulus Zylon fibers at temperatures between 400 mK and 4 K were performed to assess if they can be successfully employed in the design of high performance suspension systems for cold stages of adiabatic demagnetization refrigerators. The linear mass density of the yarn used in these measurements amounts to 3270 dtex, which is also a measure for the yarn's cross section. The experimental data for the thermal conductivity was fitted to a function of the form λZ=(1010±30)·TpWmmdtexK. This result was normalized to the breaking strength of the fibers and compared with Kevlar. It shows that Kevlar outperforms Zylon in the investigated temperature range. At 1.5 K, the thermal conductivity integral of Zylon yarn is twice as high as the thermal conductivity integral of Kevlar yarn with the same breaking strength. A linear mass density of 1 tex is equivalent to a yarn mass of 1 g/km. High modulus Zylon has a density of 1.56 g/cm 3.
Choo, Hyunwook; Nam, Hongyeop; Lee, Woojin
2017-12-01
The composition of naturally cemented deposits is very complicated; thus, estimating the maximum shear modulus (Gmax, or shear modulus at very small strains) of cemented sands using the previous empirical formulas is very difficult. The purpose of this experimental investigation is to evaluate the effects of particle size and cement type on the Gmax and unconfined compressive strength (qucs) of cemented sands, with the ultimate goal of estimating Gmax of cemented sands using qucs. Two sands were artificially cemented using Portland cement or gypsum under varying cement contents (2%-9%) and relative densities (30%-80%). Unconfined compression tests and bender element tests were performed, and the results from previous studies of two cemented sands were incorporated in this study. The results of this study demonstrate that the effect of particle size on the qucs and Gmax of four cemented sands is insignificant, and the variation of qucs and Gmax can be captured by the ratio between volume of void and volume of cement. qucs and Gmax of sand cemented with Portland cement are greater than those of sand cemented with gypsum. However, the relationship between qucs and Gmax of the cemented sand is not affected by the void ratio, cement type and cement content, revealing that Gmax of the complex naturally cemented soils with unknown in-situ void ratio, cement type and cement content can be estimated using qucs.
Reinforced concrete bridges: effects due to corrosion and concrete young modulus variation
Directory of Open Access Journals (Sweden)
P. T. C. Mendes
Full Text Available Most of the Brazilian bridges of federal road network are made of reinforced concrete and are more than 30 years old, with little information about the mechanical properties of their constitutive materials. Along the service life of these bridges much modification occurred on vehicles load and geometry and in design standard. Many of them show signs of concrete and steel deterioration and their stability conditions are unknown. With the aim of contributing to the structural evaluation of reinforced concrete bridges it was decided to analyze the stresses in reinforced concrete bridge sections to verify the effects due to reinforcement corrosion and variation of the concrete Young modulus on the stress distribution regarding several load patterns and cracking effects in a representative bridge of the Brazilian road network with different longitudinal reinforcement taxes and two concrete Young modulus, Ec and 0.5Ec, and with different percentage of reinforcement corrosion. The analysis considered two finite element models: frame and shell elements as well as solid elements. The results indicate that these variation effects are more significant in reinforcement bars than in concrete.
Directory of Open Access Journals (Sweden)
Zuhua Zhang
2016-08-01
Full Text Available The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm is considered. This critical void model is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Superior hardness and Young's modulus of low temperature nanocrystalline diamond coatings
Energy Technology Data Exchange (ETDEWEB)
Cicala, G., E-mail: grazia.cicala@ba.imip.cnr.it [CNR-IMIP Bari, Via G. Amendola 122/D, 70126 Bari (Italy); Magaletti, V. [ALTA S.p.A., via Gherardesca 5, 56121 Ospedaletto (Pisa) (Italy); Senesi, G.S. [CNR-IMIP Bari, Via G. Amendola 122/D, 70126 Bari (Italy); Carbone, G. [DIMeG-Politecnico di Bari Viale Japigia 182, 70126 Bari (Italy); Altamura, D.; Giannini, C. [CNR-IC Bari, Via G. Amendola 122/D, 70126 Bari (Italy); Bartali, R. [Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo (Trento) (Italy)
2014-04-01
Nanocrystalline diamond (NCD) coatings with thickness of about 3 μm were grown on silicon substrates at four deposition temperatures ranging from 653 to 884 °C in CH{sub 4}/H{sub 2}/Ar microwave plasmas. The morphology, structure, chemical composition and mechanical and surface properties were studied by means of Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Raman spectroscopy, nanoindentation and Water Contact Angle (WCA) techniques. The different deposition temperatures used enabled to modulate the chemical, structural and mechanical NCD properties, in particular the grain size and the shape. The characterization measurements revealed a relatively smooth surface morphology with a variable grain size, which affected the incorporated hydrogen amount and the sp{sup 2} carbon content, and, as a consequence, the mechanical properties. Specifically, the hydrogen content decreased by increasing the grain size, whereas the sp{sup 2} carbon content increased. The highest values of hardness (121 ± 25 GPa) and elastic modulus (1036 ± 163 GPa) were achieved in NCD film grown at the lowest value of deposition temperature, which favored the formation of elongated nanocrystallites characterized by improved hydrophobic surface properties. - Highlights: • We produce the hardest NCD coating at the lowest deposition temperature. • We modify the deposition temperature to tailor the grain size and shape of the NCD coatings. • We assess the mechanical properties (hardness and elastic modulus) of superhard NCD coating on a soft silicon substrate.
Low modulus and bioactive Ti/α-TCP/Ti-mesh composite prepared by spark plasma sintering.
Guo, Yu; Tan, Yanni; Liu, Yong; Liu, Shifeng; Zhou, Rui; Tang, Hanchun
2017-11-01
A titanium mesh scaffold composite filled with Ti/α-TCP particles was prepared by spark plasma sintering (SPS). The microstructures and interfacial reactions of the composites were investigated by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The compressive strength and elastic modulus were also measured. In vitro bioactivity and biocompatibility was evaluated by using simulated body fluid and cells culture, respectively. After high temperature sintering, Ti oxides, TixPy and CaTiO3 were formed. The formation of Ti oxides and TixPy were resulted from the diffusion of O and P elements from α-TCP to Ti. CaTiO3 was the reaction product of Ti and α-TCP. The composite of 70Ti/α-TCP incorporated with Ti mesh showed a high compressive strength of 589MPa and a low compressive modulus of 30GPa. The bioactivity test showed the formation of a thick apatite layer on the composite and well-spread cells attachment. A good combination of mechanical properties and bioactivity indicated a high potential application of Ti/α-TCP/Ti-mesh composite for orthopedic implants. Copyright © 2017. Published by Elsevier B.V.
Ojeda, Cassandra E.; Oakes, Eric J.; Hill, Jennifer R.; Aldi, Dominic; Forsberg, Gustaf A.
2011-01-01
A study was performed to observe how changes in temperature and substrate material affected the strength and modulus of an adhesive bondline. Seven different adhesives commonly used in aerospace bonded structures were tested. Aluminum, titanium and Invar adherends were cleaned and primed, then bonded using the manufacturer's recommendations. Following surface preparation, the coupons were bonded with the adhesives. The single lap shear coupons were then pull tested per ASTM D 1002 Standard Test Method for Apparent Shear Strength of Single- Lap-Joint over a temperature range from -150 deg C up to +150 deg C. The ultimate strength was calculated and the resulting data were converted into B-basis design allowables. Average and Bbasis results were compared. Results obtained using aluminum adherends are reported. The effects of using different adherend materials and temperature were also studied and will be reported in a subsequent paper. Dynamic Mechanical Analysis (DMA) was used to study variations in adhesive modulus with temperature. This work resulted in a highly useful database for comparing adhesive performance over a wide range of temperatures, and has facilitated selection of the appropriate adhesive for spacecraft structure applications.
Directory of Open Access Journals (Sweden)
Hassan S. OTUOZE
2015-12-01
Full Text Available Traditional asphalt tests like Hveem and Marshall tests are at best mere characterization than effective test of pavement field performance because of complex viscoelastic behavior of asphalt. Mechanical properties otherwise called simple performance tests (SPT are performance criteria of asphalt. Dynamic modulus among other SPT’s like permanent deformation, fatigue cracking, thermal cracking, moisture susceptibility, shear and friction properties; determines stress-strain to time-temperature relationships that imparts on strength, service life and durability. The test followed the recommendations of NCHRP 1-37a (2004 and mixes were prepared using 0, 0.5, 1.0 and 1.5% HDPP contents. The parameters tested for dynamic modulus, /E*/, are stiffness, recoverable strain (ε, and phase angle (ξ. Time – temperature superposition (TTS called master curve was fitted using sigmoidal curve to interpolate the parameters beyond measured data set so as to observe the viscoelastic behavior outside the physical properties. The performance of 0.5% HDPP asphalt is better enhanced than the conventional asphalt to improve upon strength, service and durability.
Shojaee, S. A.; Qi, Y.; Wang, Y. Q.; Mehner, A.; Lucca, D. A.
2017-01-01
Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. In this study, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. The results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. It was found that carbon was present in a non-graphitic sp2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. A combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films.
Nordbotten, Bernt J; Tronstad, Christian; Martinsen, Ørjan G; Grimnes, Sverre
2011-07-01
This paper addresses the problem of calculating the bioimpedance phase angle from measurements of impedance modulus. A complete impedance measurement was performed on altogether 20 healthy persons using a Solatron 1260/1294 system. The obtained impedance modulus (absolute impedance value) values were used to calculate the Cole parameters and from them the phase angles. In addition, the phase angles were also calculated using a Kramers-Kronig approach. A correlation analysis for all subjects at each frequency (5, 50, 100 and 200 kHz) for both methods gave R(2) values ranging from 0.7 to 0.96 for the Cole approach and from 0.83 to 0.96 for the Kramers-Kronig approach; thus, both methods gave good results compared with the complete measurement results. From further statistical significance testing of the absolute value of the difference between measured and calculated phase angles, it was found that the Cole equation method gave significantly better agreement for the 50 and 100 kHz frequencies. In addition, the Cole equation method gives the four Cole parameters (R(0), R(∞), τ(z) and α) using measurements at frequencies up to 200 kHz while the Kramers-Kronig method used frequencies up to 500 kHz to reduce the effect of truncation on the calculated results. Both methods gave results that can be used for further bioimpedance calculations, thus improving the application potential of bioimpedance measurement results obtained using relatively inexpensive and portable measurement equipment.
Zhang, Zuhua; Wang, Hao
2016-08-01
The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Directory of Open Access Journals (Sweden)
Yunjiao Bai
2015-01-01
Full Text Available The traditional fourth-order nonlinear diffusion denoising model suffers the isolated speckles and the loss of fine details in the processed image. For this reason, a new fourth-order partial differential equation based on the patch similarity modulus and the difference curvature is proposed for image denoising. First, based on the intensity similarity of neighbor pixels, this paper presents a new edge indicator called patch similarity modulus, which is strongly robust to noise. Furthermore, the difference curvature which can effectively distinguish between edges and noise is incorporated into the denoising algorithm to determine the diffusion process by adaptively adjusting the size of the diffusion coefficient. The experimental results show that the proposed algorithm can not only preserve edges and texture details, but also avoid isolated speckles and staircase effect while filtering out noise. And the proposed algorithm has a better performance for the images with abundant details. Additionally, the subjective visual quality and objective evaluation index of the denoised image obtained by the proposed algorithm are higher than the ones from the related methods.
Le Fur, Yann; Cozzone, Patrick J
2015-02-01
In a previous study, we have shown that modulus post-processing is a simple and efficient tool to both phase correct and frequency align magnetic resonance (MR) spectra automatically. Furthermore, this technique also eliminates sidebands and phase distortions. The advantages of the modulus technique have been illustrated in several applications to brain proton MR spectroscopy. Two possible drawbacks have also been pointed out. The first one is the theoretical decrease in signal-to-noise ratio (SNR) by a factor up to √2 when comparing the spectrum obtained after modulus versus conventional post-processing. The second pitfall results from the symmetrization of the spectrum induced by modulus post-processing, since any resonance or artifact located at the left of the water resonance is duplicated at the right of the water resonance, thus contaminating the region of the spectrum containing the resonances of interest. Herein, we propose a strategy in order to eliminate these two limitations. Concerning the SNR issue, two complementary approaches are presented here. The first is based on the application of modulus post-processing before spatial apodization, and the second consists in substituting the left half of the spectrum by the fit of the water resonance before applying modulus post-processing. The symmetrization induced by modulus post-processing then combines the right half of the original spectrum containing the resonances of interest with the left half of the water fit, free of noise and artifacts. Consequently, the SNR is improved when compared to modulus post-processing alone. As a bonus, any artifact or resonance present in the left half of the original spectrum is removed. This solves the second limitation. After validation of the technique on simulations, we demonstrated that this improvement of the modulus technique is significantly advantageous for both in vitro and in vivo applications. By improving the SNR of the spectra and eliminating eventual
Structural determinants in the bulk heterojunction.
Acocella, Angela; Höfinger, Siegfried; Haunschmid, Ernst; Pop, Sergiu C; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato; Zerbetto, Francesco
2018-02-21
Photovoltaics is one of the key areas in renewable energy research with remarkable progress made every year. Here we consider the case of a photoactive material and study its structural composition and the resulting consequences for the fundamental processes driving solar energy conversion. A multiscale approach is used to characterize essential molecular properties of the light-absorbing layer. A selection of bulk-representative pairs of donor/acceptor molecules is extracted from the molecular dynamics simulation of the bulk heterojunction and analyzed at increasing levels of detail. Significantly increased ground state energies together with an array of additional structural characteristics are identified that all point towards an auxiliary role of the material's structural organization in mediating charge-transfer and -separation. Mechanistic studies of the type presented here can provide important insights into fundamental principles governing solar energy conversion in next-generation photovoltaic devices.
Bulk and shear viscosity in Hagedorn fluid
Energy Technology Data Exchange (ETDEWEB)
Tawfik, A.; Wahba, M. [Egyptian Center for Theoretical Physics (ECTP), MTI University, Faculty of Engineering, Cairo (Egypt)
2010-11-15
Assuming that the Hagedorn fluid composed of known particles and resonances with masses m <2 GeV obeys the first-order theory (Eckart) of relativistic fluid, we discuss the transport properties of QCD confined phase. Based on the relativistic kinetic theory formulated under the relaxation time approximation, expressions for bulk and shear viscosity in thermal medium of hadron resonances are derived. The relaxation time in the Hagedorn dynamical fluid exclusively takes into account the decay and eventually van der Waals processes. We comment on the in-medium thermal effects on bulk and shear viscosity and averaged relaxation time with and without the excluded-volume approach. As an application of these results, we suggest the dynamics of heavy-ion collisions, non-equilibrium thermodynamics and the cosmological models, which require thermo- and hydro-dynamics equations of state. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
Enhanced bulk polysilicon production using silicon tubes
Jafri, Ijaz; Chandra, Mohan; Zhang, Hui; Prasad, Vish; Reddy, Chandra; Amato-Wierda, Carmela; Landry, Marc; Ciszek, Ted
2001-05-01
A novel technique using silicon tubes for the production of bulk polysilicon via chemical vapor deposition is presented. Our experimental studies with a model reactor indicate that the polysilicon growth inside the silicon tube (15.3 g) exceeds that of the calculated polysilicon growth on silicon slim rods (4.3 g) over 55 h of deposition time. A computational model is also being developed to simulate the growth rates of the model reactor. Preliminary computational results from this model show a slightly asymmetric temperature distribution at the reactor center line with a 1000 sccm argon flow at 850°C reactor temperature. Both these experimental and computational modeling studies have identified key criteria for the prototype reactor being designed for bulk polysilicon growth.
Internal shear cracking in bulk metal forming
DEFF Research Database (Denmark)
Christiansen, Peter; Nielsen, Chris Valentin; Bay, Niels Oluf
2017-01-01
This paper presents an uncoupled ductile damage criterion for modelling the opening and propagation of internal shear cracks in bulk metal forming. The criterion is built upon the original work on the motion of a hole subjected to shear with superimposed tensile stress triaxiality and its overall...... performance is evaluated by means of side-pressing formability tests in Aluminium AA2007-T6 subjected to different levels of pre-strain. Results show that the new proposed criterionis able to combine simplicity with efficiency for predicting the onset of fracture and the crack propagation path for the entire...... cracking to internal cracks formed undert hree-dimensional states of stress that are typical of bulk metal forming....
Microfabricated bulk wave acoustic bandgap device
Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, Carol
2010-06-08
A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).
Multilayer Integrated Film Bulk Acoustic Resonators
Zhang, Yafei
2013-01-01
Multilayer Integrated Film Bulk Acoustic Resonators mainly introduces the theory, design, fabrication technology and application of a recently developed new type of device, multilayer integrated film bulk acoustic resonators, at the micro and nano scale involving microelectronic devices, integrated circuits, optical devices, sensors and actuators, acoustic resonators, micro-nano manufacturing, multilayer integration, device theory and design principles, etc. These devices can work at very high frequencies by using the newly developed theory, design, and fabrication technology of nano and micro devices. Readers in fields of IC, electronic devices, sensors, materials, and films etc. will benefit from this book by learning the detailed fundamentals and potential applications of these advanced devices. Prof. Yafei Zhang is the director of the Ministry of Education’s Key Laboratory for Thin Films and Microfabrication Technology, PRC; Dr. Da Chen was a PhD student in Prof. Yafei Zhang’s research group.
A large-scale biomass bulk terminal
Wu, M.R.
2012-01-01
This research explores the possibility of a large-scale bulk terminal in West Europe dedicated to handle solid and liquid biomass materials. Various issues regarding the conceptual design of such a terminal have been investigated and demonstrated in this research: the potential biomass materials that will be the major international trade flows in the future, the characteristics of these potential biomass materials, the interaction between the material properties and terminal equipment, the pe...
Raman characterization of bulk ferromagnetic nanostructured graphite
Energy Technology Data Exchange (ETDEWEB)
Pardo, Helena, E-mail: hpardo@fq.edu.uy [Centro NanoMat, Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica, Cno. Aparicio Saravia s/n, 91000, Pando, Canelones (Uruguay); Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DETEMA, Facultad de Quimica, Universidad de la Republica, Gral. Flores 2124, P.O. Box 1157, Montevideo (Uruguay); Divine Khan, Ngwashi [Mantfort University, Leicester (United Kingdom); Faccio, Ricardo [Centro NanoMat, Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica, Cno. Aparicio Saravia s/n, 91000, Pando, Canelones (Uruguay); Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DETEMA, Facultad de Quimica, Universidad de la Republica, Gral. Flores 2124, P.O. Box 1157, Montevideo (Uruguay); Araujo-Moreira, F.M. [Grupo de Materiais e Dispositivos-CMDMC, Departamento de Fisica e Engenharia Fisica, UFSCar, Caixa Postal 676, 13565-905, Sao Carlos SP (Brazil); Fernandez-Werner, Luciana [Centro NanoMat, Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica, Cno. Aparicio Saravia s/n, 91000, Pando, Canelones (Uruguay); Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DETEMA, Facultad de Quimica, Universidad de la Republica, Gral. Flores 2124, P.O. Box 1157, Montevideo (Uruguay)
2012-08-15
Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm{sup -1} showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.
Depleted Bulk Heterojunction Colloidal Quantum Dot Photovoltaics
Barkhouse, D. Aaron R.
2011-05-26
The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows for high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar devices. A record power conversion of 5.5% under simulated AM 1.5 illumination conditions is reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Longitudinal bulk a coustic mass sensor
DEFF Research Database (Denmark)
Hales, Jan Harry; Teva, Jordi; Boisen, Anja
2009-01-01
Design, fabrication and characterization, in terms of mass sensitivity, is presented for a polycrystalline silicon longitudinal bulk acoustic cantilever. The device is operated in air at 51 MHz, resulting in a mass sensitivity of 100 HZ/fg (1 fg = 10{su−15 g). The initial characterization...... is conducted by depositing a minute mass by means of focused ion beam. The total noise in the currently applied measurement system allows for a mass resolution of 0.4 fg in air....
Scaling Bulk Data Analysis with Mapreduce
2017-09-01
Writing Bulk_Extractor MapReduce 101 List of References 105 viii Initial Distribution List 113 ix THIS PAGE INTENTIONALLY LEFT BLANK x List of Figures...dedicated Experts -Formal definition presented -Large technology growth -Everyone has email, cell phones, networks Adolescence -Growth in Academics ...period is where we see those requirements come to fruition with an explosive growth into the academic community. This period marks a point where research
An Extended Hardness Limit in Bulk Nanoceramics
2014-01-01
to fabricate bulk, fully dense and high-purity nanocrystalline ceramics with unprecedentedly small nanometer- sized grains. Using magnesium aluminate ...nanocrystalline ceramic sintered at 2 GPa and 795 C. The diffraction peaks correspond to stoichiometric magnesium aluminate [42] and a nickel ring that holds...is found to be 3.6005 ± 0.0079 g cm3, which is equal to that of stoichiometric magnesium aluminate [43] and reveals that the produced ceramics are
Ma, Xinyue; Zare, Yasser; Rhee, Kyong Yop
2017-12-01
A two-step technique based on micromechanical models is suggested to determine the influence of aggregated/agglomerated nanoparticles on Young's modulus of polymer nanocomposites. The nanocomposite is assumed to include nanoparticle aggregation/agglomeration and effective matrix phases. This method is examined for different samples, and the effects of important parameters on the modulus are investigated. Moreover, the highest and the lowest levels of predicted modulus are calculated based on the current methodology. The suggested technique can correctly predict Young's modulus for the samples assuming the aggregation/agglomeration of nanoparticles. Additionally, the aggregation/agglomeration of nanoparticles decreases Young's modulus of polymer nanocomposites. It is demonstrated that the high modulus of nanoparticles is not sufficient to obtain a high modulus in nanocomposites, and the surface chemistry of components should be adjusted to prevent aggregation/agglomeration and to disperse nano-sized particles in the polymer matrix.
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Ahmadian Khoshemehr Leila
2009-09-01
Full Text Available Background: Luting agents are used to attach indirect restoration into or on the tooth. Poor mechanical properties of cement may be a cause of fracture of this layer and lead to caries and restoration removal. The purpose of this study was to compare the elastic modulus and compressive strength of Ariadent (A Poly and Harvard polycarboxylate (H Poly cements and Vitremer resin modified glass ionomer (RGl.Materials & Methods: In this experimental study 15 specimens were prepared form each experimental cement in Laboratory of Tehran Oil Refining Company. The cylindrical specimens were compressed in Instron machine after 24 hours. Elastic modulus and compressive strength were calculated from stress/strain curve of each specimen. One way ANOVA and Tukey tests were used for statistical analysis and P values<0.05 were considered to be statistically significant.Results: The mean elastic modulus and mean compressive strength were 2.2 GPa and 87.8MPa in H poly, 2.4 GPa and 56.5 MPa in A Poly, and 0.8GPa and 105.6 MPa in RGI, respectively. Statistical analysis showed that compressive strength and elastic modulus of both polycarboxylate cements were significantly different from hybrid ionomer (P<0.05, but the difference between elastic modulus of two types of polycarboxilate cements was not statistically significant. Compressive strength of two polycarboxilate cements were significantly different (P<0.05. Conclusion: An ideal lutting agent must have the best mechanical properties. Between the tested luttins RGl cement had the lowest elastic modulus and the highest compressive strength, but the A poly cement had the highest elastic modulus and the lowest compressive strength. Therefore none of them was the best.
Tailoring Magnetic Properties in Bulk Nanostructured Solids
Morales, Jason Rolando
Important magnetic properties and behaviors such as coercivity, remanence, susceptibility, energy product, and exchange coupling can be tailored by controlling the grain size, composition, and density of bulk magnetic materials. At nanometric length scales the grain size plays an increasingly important role since magnetic domain behavior and grain boundary concentration determine bulk magnetic behavior. This has spurred a significant amount of work devoted to developing magnetic materials with nanometric features (thickness, grain/crystallite size, inclusions or shells) in 0D (powder), 1D (wires), and 2D (thin films) materials. Large 3D nanocrystalline materials are more suitable for many applications such as permanent magnets, magneto-optical Faraday isolators etc. Yet there are relatively few successful demonstrations of 3D magnetic materials with nanoscale influenced properties available in the literature. Making dense 3D bulk materials with magnetic nanocrystalline microstructures is a challenge because many traditional densification techniques (HIP, pressureless sintering, etc.) move the microstructure out of the "nano" regime during densification. This dissertation shows that the Current Activated Pressure Assisted Densification (CAPAD) method, also known as spark plasma sintering, can be used to create dense, bulk, magnetic, nanocrystalline solids with varied compositions suited to fit many applications. The results of my research will first show important implications for the use of CAPAD for the production of exchange-coupled nanocomposite magnets. Decreases in grain size were shown to have a significant role in increasing the magnitude of exchange bias. Second, preferentially ordered bulk magnetic materials were produced with highly anisotropic material properties. The ordered microstructure resulted in changing magnetic property magnitudes (ex. change in coercivity by almost 10x) depending on the relative orientation (0° vs. 90°) of an externally
Measuring permeability, Young's modulus, and stress relaxation by the beam-bending technique
Vichit-Vadakan, Wilasa
Recent interest in the permeability of cement paste, mortars, and concrete lies in the need to gain further understanding of mechanisms affecting the durability of these materials. Conventional techniques for measuring permeability are cumbersome and often take days to complete just one measurement. This thesis proposes a new technique for measuring the permeability. The advantage of this technique is that the results are obtained in a few minutes to a few hours; moreover, there is no problem with leaks or need for high pressures. The method is particularly well suited for examining the changes in permeability and viscoelastic properties of young cement paste samples. When a saturated rod of a porous material is instantaneously deflected under three-point bending, two types of relaxation processes occur simultaneously: hydrodynamic relaxation, caused by the flow of liquid in the porous body to restore ambient pressure, and viscoelastic relaxation of the solid network. By measuring the decrease in the force required to sustain a constant deflection, it is possible to obtain the permeability and Young's modulus from the hydrodynamic relaxation function, in addition to the stress relaxation function of the sample. The exact viscoelastic solution is developed and the total relaxation is shown to be very closely approximated as the product of the hydrodynamic and stress relaxation functions. The analytical results are verified on porous VycorRTM glass saturated in various solvents, including normal alcohols, water, and glycerol. The results show excellent agreement with the theory. Consistent with observations of previous workers, the permeability is found to be influenced by the size of the solvent molecule; by assuming that the pore surfaces are covered with a monolayer of immobile solvent, the observed variation can be explained. The evolution of the permeability, Young's modulus, and stress relaxation function are reported for Type III Portland cement paste with
Singh Yadav, Raghvendra; Kuřitka, Ivo; Vilcakova, Jarmila; Havlica, Jaromir; Masilko, Jiri; Kalina, Lukas; Tkacz, Jakub; Švec, Jiří; Enev, Vojtěch; Hajdúchová, Miroslava
2017-12-01
In this work CoFe2O4 spinel ferrite nanoparticles were synthesized by honey mediated sol-gel combustion method and further annealed at higher temperature 500 °C, 700 °C, 900 °C and 1100 °C. The synthesized spinel ferrite nanoparticles is investigated by x-ray diffraction, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), field emission scanning electron microscopy, x-ray photoelectron spectroscopy and vibrating sample magnetometer. The x-ray diffraction study reveals face-centered cubic spinel cobalt ferrite crystal phase formation. The crystallite size and lattice parameter are increased with annealing temperature. Raman and Fourier transform infrared spectra also confirm spinel ferrite crystal structure of synthesized nanoparticles. The existence of cation at octahedral and tetrahedral site in cobalt ferrite nanoparticles is confirmed by x-ray photoelectron spectroscopy. Magnetic measurement shows increased saturation magnetization 74.4 emu g-1 at higher annealing temperature 1100 °C, high coercivity 1347.3 Oe at lower annealing temperature 500 °C, and high remanent magnetization 32.3 emu g-1 at 900 °C annealing temperature. The magnetic properties of synthesized ferrite nanoparticles can be tuned by adjusting sizes through annealing temperature. Furthermore, the dielectric constant and ac conductivity shows variation with frequency (1-107 Hz), grain size and cation redistribution. The modulus spectroscopy study reveals the role of bulk grain and grain boundary towards the resistance and capacitance. The cole-cole plots in modulus formalism also well support the electrical response of nanoparticles originated from both grain and grain boundaries. The dielectric, electrical, magnetic, impedance and modulus spectroscopic characteristics of synthesized CoFe2O4 spinel ferrite nanoparticles demonstrate the applicability of these nanoparticles for magnetic recording, memory
Mullin, Scott; Panday, Ashoutosh; Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
2014-04-22
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics. In another aspect, the electrolyte exhibits a conductivity drop when the temperature of electrolyte increases over a threshold temperature, thereby providing a shutoff mechanism for preventing thermal runaway in lithium battery cells.
Demichelis, A; Divieto, C; Mortati, L; Pavarelli, S; Sassi, G; Sassi, M P
2015-04-13
The validation of the AFM method for elastic modulus E measurement in soft materials (E elasticity, within tissues, has recently been recognized as a marker of metastatic potential. To measure a cell elasticity difference, reproducible E measurements in biological samples are needed. In this work a robust method for a metrological validation of E measurements in the range 500-5000 kPa was developed, based on the realization of thick E standard samples and on the study of the interactions between the measurement process and the sample at micro- and nano-scale. E measurement reproducibility limit of 4% has been reached. This allows designing a very sensitive and reproducible measurement of E in biological samples representing thus a powerful diagnostic tool for cancer detection. Copyright © 2015 Elsevier Ltd. All rights reserved.
Influence of testing methods to determine the bending modulus of elasticity of wood
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Diogo Aparecido Lopes
2016-04-01
Full Text Available In Brazil, the characterization of solid wood for structural design must be carried out according to the recommendations of the ABNT NBR 7190:1997 standards. Studies about alternatives to improve reliability to test methods are always relevant. Thus, the present study aims to examine the bending modulus of elasticity of samples of three wood species: Canelão (Nectandra membranacea, Corymbia citriodora (Corymbia citriodora and Angelim (Angelim sp. The results for Canelão and Angelim showed statistical equivalence between the methods at 5% significance level. However, for the Corymbia species, statistical differences of results for bending tests with three and four points were observed. More studies are recommended in order to investigate other wood species, different strength classes and moisture content ranges.
Objectification of Modulus Elasticity of Foam Concrete Poroflow 17-5 on the Subbase Layer
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Hájek Matej
2016-05-01
Full Text Available Principles of sustainable development create the need to develop new building materials. Foam concrete is a type of lightweight concrete that has many advantages compared to conventional building materials, for example low density and thermal insulation characteristics. With current development level, any negatively influencing material features are constantly eliminated as well. This paper is dealing with substitution of hydraulically bound mixtures by cement foam concrete Poroflow 17-5. The executed assessment is according to the methodology of assessing the existing asphalt pavements in Slovak Republic. The ex post calculation was used to estimate modulus range for Poroflow 17-5 based on the results of static load tests conducted using the Testing Experiment Equipment.
Kim, Wansun; Lee, Inhwa; Kim, Dong Yoon; Yu, Youn-Yeol; Jung, Hae-Yoon; Kwon, Seyeoul; Park, Weon Seo; Kim, Taek-Soo
2017-05-01
To protect brittle layers in organic photovoltaic devices, the mechanical neutral plane strategy can be adopted through placing the brittle functional materials close to the neutral plane where stress and strain are zero during bending. However, previous research has been significantly limited in the location and number of materials to protect through using a single neutral plane. In this study, multiple neutral planes are generated using low elastic modulus adhesives and are controlled through quantitative analyses in order to protect the multiple brittle materials at various locations. Moreover, the protection of multiple brittle layers at various locations under both concave and convex bending directions is demonstrated. Multilayer structures that have soft adhesives are further analyzed using the finite element method analysis in order to propose guidelines for structural design when employing multiple neutral planes.
Predicting Concrete Compressive Strength and Modulus of Rupture Using Different NDT Techniques
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Wilfrido Martínez-Molina
2014-01-01
Full Text Available Quality tests applied to hydraulic concrete such as compressive, tension, and bending strength are used to guarantee proper characteristics of materials. All these assessments are performed by destructive tests (DTs. The trend is to carry out quality analysis using nondestructive tests (NDTs as has been widely used for decades. This paper proposes a framework for predicting concrete compressive strength and modulus of rupture by combining data from four NDTs: electrical resistivity, ultrasonic pulse velocity, resonant frequency, and hammer test rebound with DTs data. The model, determined from the multiple linear regression technique, produces accurate indicators predictions and categorizes the importance of each NDT estimate. However, the model is identified from all the possible linear combinations of the available NDT, and it was selected using a cross-validation technique. Furthermore, the generality of the model was assessed by comparing results from additional specimens fabricated afterwards.
Hardness and Elastic Modulus on Six-Fold Symmetry Gold Nanoparticles
Ramos, Manuel; Ortiz-Jordan, Luis; Hurtado-Macias, Abel; Flores, Sergio; Elizalde-Galindo, José T.; Rocha, Carmen; Torres, Brenda; Zarei-Chaleshtori, Maryam; Chianelli, Russell R.
2013-01-01
The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H2O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface. PMID:28809302
Electric Modulus Studies of Low Energy Ar9+ Irradiated Conducting Polymer PANI-PVA
Himanshu, A. K.; Bandyopadhyay, S. K.; Sen, Pintu; Sinha, T. P.
2011-07-01
Polyaniline (PANI) prepared using water soluble support polymer polyvinyl alcohol (PVA) was subjected to irradiation with 150 keV Argon (Ar9+) ion at the fluence of 7.68×1014 ion/cm2 with beam current of 2 μA (electrical). There has been implantation of Ar atoms. The field dependence of electric modulus response has been measured in a frequency range from 100 Hz to 1 MHz and in a temperature range from room temperature to the glass transition. Ar9+ implantation in PANI-PVA shifts the peak maximum to the lower frequency. Resistivity analysis earlier showed a decrease in the localization length as well as increase in the energy gap due to the scission of bonds by the energy deposited by Ar9+ ions.
An Experimental Simulation to Validate FEM to Predict Transverse Young’s Modulus of FRP Composites
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V. S. Sai
2013-01-01
Full Text Available Finite element method finds application in the analysis of FRP composites due to its versatility in getting the solution for complex cases which are not possible by exact classical analytical approaches. The finite element result is questionable unless it is obtained from converged mesh and properly validated. In the present work specimens are prepared with metallic materials so that the arrangement of fibers is close to hexagonal packing in a matrix as similar arrangement in case of FRP is complex due to the size of fibers. Transverse Young’s moduli of these specimens are determined experimentally. Equivalent FE models are designed and corresponding transverse Young’s moduli are compared with the experimental results. It is observed that the FE values are in good agreement with the experimental results, thus validating FEM for predicting transverse modulus of FRP composites.
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Kundu, Ranadip [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India); Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Roy, Debasish [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Bhattacharya, Sanjib, E-mail: sanjib_ssp@yahoo.co.in [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India)
2017-02-15
Ionic conductivity and dielectric behavior of Ag{sub 2}O–CdI{sub 2}–CdO nanocomposite system have been studied. X-ray diffraction has been carried out to obtain the crystallite sizes and the growth of CdO dispersed in glass-matrices. Total conductivity of them shows thermally activated nature. It is observed that total conductivity decreases and corresponding activation energy for conduction follows opposite behavior. The high-frequency ac conductivity may correspond to a nonrandom, correlated and sub-diffusive motion of Ag{sup +} ions. Conductivity relaxation time is found to increase. The nature of scaling of the conductivity as well as modulus spectra indicates that the electrical relaxation of Ag{sup +} is temperature independent but depends upon composition.
Background data for modulus mapping high-performance polyethylene fiber morphologies
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Kenneth E. Strawhecker
2017-02-01
Full Text Available The data included here provides a basis for understanding “Interior morphology of high-performance polyethylene fibers revealed by modulus mapping” (K.E. Strawhecker, E.J. Sandoz-Rosado, T.A. Stockdale, E.D. Laird, 2016 [1], in specific: the multi-frequency (AMFM atomic force microscopy technique and its application to ultra-high-molecular-weight Polyethylene (UHMWPE fibers. Furthermore, the data suggests why the Hertzian contact mechanics model can be used within the framework of AMFM theory, simple harmonic oscillator theory, and contact mechanics. The framework is first laid out followed by data showing cantilever dynamics, force-distance spectra in AC mode, and force-distance in contact mode using Polystyrene reference and UHMWPE. Finally topography and frequency shift (stiffness maps are presented to show the cases where elastic versus plastic deformation may have occurred.
Elastic modulus of suspended purple membrane measured by atomic force microscopy
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Siitonen, Ari M. [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan); Sumitomo, Koji [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)], E-mail: sumitomo@will.brl.ntt.co.jp; Ramanujan, Chandra S. [Bionanotechnology IRC, Clarendon Laboratory, University of Oxford, Oxfordshire OX1 3PU (United Kingdom); Shinozaki, Youichi; Kasai, Nahoko; Furukawa, Kazuaki [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan); Ryan, John F. [Bionanotechnology IRC, Clarendon Laboratory, University of Oxford, Oxfordshire OX1 3PU (United Kingdom); Torimitsu, Keiichi [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)
2008-09-30
We have probed the mechanical properties of purple membrane (PM) in a physiological environment using the atomic force microscope (AFM). By suspending PM over nano-trenches, the elastic properties of PM can be evaluated free from the interaction with the substrate. Force-displacement curves were obtained on the suspended membrane and the data was compared to that of a simple model of a thin film over a trench. By fitting the data to the model, the elastic modulus of PM was estimated to be 8 MPa. When the membrane is repeatedly indented, we observed a change in the force-distance data consistent with damage to the two-dimensional crystal of PM. In this paper we demonstrate that the AFM allows us to evaluate the mechanics of biological membranes in their native conditions.
Laminated beams: deflection and stress as a function of epoxy shear modulus
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Bialek, J.
1976-01-01
The large toroidal field coil deflections observed during the PLT power test are due to the poor shear behavior of the insulation material used between layers of copper. Standard techniques for analyzing such laminated structures do not account for this effect. This paper presents an analysis of laminated beams that corrects this deficiency. The analysis explicitly models the mechanical behavior of each layer in a laminated beam and hence avoids the pitfalls involved in any averaging technique. In particular, the shear modulus of the epoxy in a laminated beam (consisting of alternate layers of metal and epoxy) may span the entire range of values from zero to classical. Solution of the governing differential equations defines the stress, strain, and deflection for any point within a laminated beam. The paper summarizes these governing equations and also includes a parametric study of a simple laminated beam.
Solving the {eta}-problem in hybrid inflation with Heisenberg symmetry and stabilized modulus
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Antusch, Stefan; Dutta, Koushik; Kostka, Philipp M. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany); Bastero-Gil, Mar [Departamento de Fisica Teorica y del Cosmos and Centro Andaluz de Fisica de Particulas Elementales, Universidad de Granada, 19071 Granada (Spain); King, Steve F., E-mail: antusch@mppmu.mpg.de, E-mail: mbg@ugr.es, E-mail: koushik@mppmu.mpg.de, E-mail: sfk@hep.phys.soton.ac.uk, E-mail: kostka@mppmu.mpg.de [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
2009-01-15
We propose a class of models in which the {eta}-problem of supersymmetric hybrid inflation is resolved using a Heisenberg symmetry, where the associated modulus field is stabilized and made heavy with the help of the large vacuum energy during inflation without any fine-tuning. The proposed class of models is well motivated both from string theory considerations, since it includes the commonly encountered case of no-scale supergravity Kaehler potential, and from the perspective of particle physics since a natural candidate for the inflaton in this class of models is the right-handed sneutrino which is massless during the inflationary epoch, and subsequently acquires a large mass at the end of inflation. We study a specific example motivated by sneutrino hybrid inflation with no-scale supergravity in some detail, and show that the spectral index may lie within the latest WMAP range, while the tensor-to-scalar ratio is very small.
Optical image encryption using equal modulus decomposition and multiple diffractive imaging
Fatima, Areeba; Mehra, Isha; Nishchal, Naveen K.
2016-08-01
The equal modulus decomposition (EMD) is a novel asymmetric cryptosystem based on coherent superposition which was proposed to resist the specific attack. In a subsequent work, the scheme was shown to be vulnerable to specific attack. In this paper, we counter the vulnerability through an encoding technique which uses multiple diffraction intensity pattern recordings as the input to the EMD setup in the gyrator domain. This allows suppression of the random phase mask in the EMD path. As a result, the proposed scheme achieves resistance to specific attack. The simulation results and the security analysis demonstrate that EMD based on multiple intensity pattern recording is an effective optical asymmetric cryptosystem suitable for securing data and images.
Apparatus for in-situ nondestructive measurement of Young's modulus of plate structures
Huang, Jerry Qixin (Inventor); Perez, Robert J. (Inventor); DeLangis, Leo M. (Inventor)
2005-01-01
A method and apparatus for determining stiffness of a plate-like structure including a monolithic or composite laminate plate entails disposing a device for generating an acoustical pulse against a surface of the plate and disposing a detecting device against the same surface spaced a known distance from the pulse-generating device, and using the pulse-generating device to emit a pulse so as to create an extensional wave in the plate. The detecting device is used to determine a time of flight of the wave over the known distance, and the wave velocity is calculated. A Young's modulus of the plate is determined by a processor based on the wave velocity. Methods and apparatus for evaluating both isotropic plates and anisotropic laminates are disclosed.
Too Soft to Stick: Influence of Substrate Modulus on Gecko Adhesion
Wilson, Michael; Klittich, Mena; Bernard, Craig; Rodrigo, Rochelle; Keith, Austin; Niewiarowski, Peter; Dhinojwala, Ali
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard rough tree trunks as well as soft flexible leaves. Gecko adhesion on a wide variety of hard surfaces has been extensively studied, however there has been no work focused on adhesion to soft surfaces. Here, we investigate for the first time the influence of substrate modulus on gecko adhesion using two different surfaces (cellulose acetate and polydimethylsiloxane). Understanding the limitations of the gecko system is critical for gecko experimental design as well as for the development of synthetic adhesives, particularly in the biomedical field. National Science Foundation.
Temperature and frequency dependence of AC conductivity and modulus in Cr-Doped ZnO
Junais, P. M.; Govindaraj, G.
2017-05-01
A nanocrystalline Cr-doped ZnO has been prepared by refluxing method. The samples were characterized using XRD and impedance spectroscopy. The XRD pattern shows the crystalline nature of the sample and well confirms the successful doping Cr into the host lattice. The conductivity of the sample measured in the temperature range 303-603K and in the frequency range 10Hz-1MHz. The temperature dependent dc conductivity and hopping frequency show Arrhenius behavior. AC conductivity data were analyzed using Jonscher's power law. Modulus data were analyzed using Bergman modified KWW function. Temperature dependent capacitance shows a sharp peak at 540K which may be due to ferroelectric nature of the material.
IMPACT OF THERMAL FATIGUE ON YOUNG’S MODULUS OF EPOXY ADHESIVES
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Mariusz Kłonica
2015-11-01
Full Text Available The following paper presents a comparative analysis of two epoxy-based adhesives: Hysol 9466 and Hysol 3421, prior to and after thermal shock testing. The tests focused on determining Young’s modulus. Epoxy-based materials are among the most widespread adhesive materials used as universal structural adhesives. The prepared epoxy samples (Hysol 9466 and Hysol 3421 were subjected to thermal shock cycling tests, according to a specified programme, in a thermal shock testing chamber, at a temperature range –40 °C to +60 °C and in the number of 200 cycles. Conclusions from the tests are presented at the final stage of the paper.
Conductivity and modulus formulation in lithium modified bismuth zinc borate glasses
Dahiya, Sajjan; Punia, R.; Murugavel, S.; Maan, A. S.
2016-05-01
The conductivity and modulus formulation in lithium modified bismuth zinc borate glasses with compositions xLi2O-(50-x) Bi2O3-10ZnO-40B2O3 has been studied in the frequency range 0.1 Hz-1.5 × 105 Hz in the temperature range 573 K-693 K. The temperature and frequency dependent conductivity is found to obey Jonscher's universal power law for all the studied compositions, the dc conductivity (σdc), crossover frequency (ωH), and frequency exponent (s) have been estimated from the fitting of the experimental data of ac conductivity with Jonscher's universal power law. Enthalpy to dissociate the cation from its original site next to a charge compensating centre (Hf) and enthalpy of migration (Hm) have been estimated. It has been observed that number of charge carriers and ac conductivity in the lithium modified bismuth zinc borate glasses increases with increase in Li2O content. Further, the conduction mechanism in the glass sample with x = 0 may be due to overlapping large polaron tunneling, whereas, conduction mechanism in other studied glass samples more or less follows diffusion controlled relaxation model. The ac conductivity is scaled using σdc and ωH as the scaling parameter and is found that these are suitable scaling parameter for conductivity scaling. Non-Debye type relaxation is found prevalent in the studied glass system. Scaling of ac conductivity as well as electric modulus confirms the presence of different type of conduction mechanism in the glass samples with x = 0 and 5 from other studied samples. The activation energy of relaxation (ER) and dc conductivity (Edc) are almost equal, suggesting that polarons/ions have to overcome same barrier while relaxing and conducting.
Berteau, Jean-Philippe; Baron, Cécile; Pithioux, Martine; Launay, Franck; Chabrand, Patrick; Lasaygues, Philippe
2014-07-01
The assessment of elastic properties in children's cortical bone is a major challenge for biomechanical engineering community, more widely for health care professionals. Even with classical clinical modalities such as X-ray tomography, MRI, and/or echography, inappropriate diagnosis can result from the lack of reference values for children bone. This study provides values for elastic properties of cortical bone in children using ultrasonic and mechanical measurements, and compares them with adult values. 18 fibula samples from 8 children (5-16 years old, mean age 10.6 years old ±4.4) were compared to 16 fibula samples from 3 elderly adults (more than 65 years old). First, the dynamic modulus of elasticity (Edyn) and Poisson's ratio (ν) are evaluated via an ultrasonic method. Second, the static modulus of elasticity (Esta) is estimated from a 3-point microbending test. The mean values of longitudinal and transverse wave velocities measured at 10 MHz for the children's samples are respectively 3.2mm/μs (±0.5) and 1.8mm/μs (±0.1); for the elderly adults' samples, velocities are respectively 3.5mm/μs (±0.2) and 1.9 mm/μs (±0.09). The mean Edyn and the mean Esta for the children's samples are respectively 15.5 GPa (±3.4) and 9.1 GPa (±3.5); for the elderly adults' samples, they are respectively 16.7 GPa (±1.9) and 5.8 GPa (±2.1). Edyn, ν and Esta are in the same range for children's and elderly adults' bone without any parametric statistical difference; a ranking correlation between Edyn and Esta is shown for the first time. Copyright © 2013 Elsevier B.V. All rights reserved.
Umehara, Jun; Nakamura, Masatoshi; Fujita, Kosuke; Kusano, Ken; Nishishita, Satoru; Araki, Kojiro; Tanaka, Hiroki; Yanase, Ko; Ichihashi, Noriaki
2017-07-01
Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography. Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver-angle combinations. The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°. This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
Serrai, Haçène; Clayton, David B; Senhadji, Lotfi; Zuo, Chun; Lenkinski, Robert E
2002-01-01
Most Magnetic Resonance Spectroscopy (MRS) localization methods can generate gradient vibrations at acoustic frequencies and/or magnetic field oscillation, which can cause a time-varying magnetic field superimposed onto the static one. This effect can produce frequency modulations of the spectral resonances. When localized MRS data are acquired without water suppression, the associated frequency modulations are manifested as a manifold of spurious peaks, called sidebands, which occur symmetrically around the water resonance. These sidebands can be larger than the small metabolite resonances and can present a problem for the quantitation of the spectra, especially at short echo times. Furthermore, the resonance lineshapes may be distorted if any low frequency modulations are present. A simple solution is presented which consists of selecting the modulus of the acquired Free Induction Decay (FID) signal. Since the frequency modulations affect only the phase of the FID signal, the obtained real spectrum of the modulus is free from the spurious peaks where quantitative results may be directly obtained. Using this method, the distortions caused by the sidebands are removed. This is demonstrated by processing proton MRS spectra acquired without water suppression collected from a phantom containing metabolites at concentrations comparable to those in human brain and from a human subject using two different localization methods (PRESS and Chemical Shift Imaging PRESS-(CSI)). The results obtained illustrate the ability of this approach to remove the spurious peaks. The corrected spectra can then be fit accurately. This is confirmed by the results obtained from both the relative and the absolute metabolites concentrations in phantoms and in vivo.
Pilarczyk, Wirginia
2016-06-01
Metallic glasses exhibit metastable structure and maintain this relatively stable amorphous state within certain temperature range. High intensity laser beam was used for the surface irradiation of Fe-Co-B-Si-Nb bulk metallic glasses. The variable parameter was laser beam pulse energy. For the analysis of structure and properties of bulk metallic glasses and their surface after laser remelting the X-ray analysis, microscopic observation and test of mechanical properties were carried out. Examination of the nanostructure of amorphous materials obtained by high pressure copper mold casting method and the irradiated with the use of TITAN 80-300 HRTEM was carried out. Nanohardness and reduced Young's modulus of particular amorphous and amorphous-crystalline material zone of the laser beam were examined with the use of Hysitron TI950 Triboindenter nanoindenter and with the use of Berkovich's indenter. The XRD and microscopic analysis showed that the test material is amorphous in its structure before irradiation. Microstructure observation with electron transmission microscopy gave information about alloy crystallization in the irradiated process. Identification of given crystal phases allows to determine the kind of crystal phases created in the first place and also further changes of phase composition of alloy. The main value of the nanohardness of the surface prepared by laser beam has the order of magnitude similar to bulk metallic glasses formed by casting process irrespective of the laser beam energy used. Research results analysis showed that the area between parent material and fusion zone is characterized by extraordinarily interesting structure which is and will be the subject of further analysis in the scope of bulk metallic glasses amorphous structure and high energy concentration source. The main goal of this work is the results' presentation of structure and chosen properties of the selected bulk metallic glasses after casting process and after irradiation
Materials for Bulk Acoustic Resonators and Filters
Loebl, Hans-Peter
2003-03-01
Highly selective solidly mounted bulk acoustic wave (BAW) band pass filters are suited for mobile and wireless systems in the GHz frequency range between 0.8 and 10 GHz. Electro-acoustic thin film BAW resonators are the building blocks these BAW filters. Piezoelectric materials used in these resonators include mainly AlN or ZnO which can be deposited by dedicated thin film sputter deposition techniques. Using these piezo-electric materials and using suited materials for the acoustic Bragg reflector, BAW resonators with high quality factors can be fabricated. The achievable filter bandwidth is approximately 4Alternatively, also ferroelectric thin films might be used to achieve higher coupling coefficient and thus filter bandwidth. BAW resonators and filters have been designed and fabricated on 6" Silicon and glass wafers. Results are presented for resonators and filters operating between 1.95 and 8 GHz. The talk will give an overview of the material aspects which are important for BAW devices. It will be shown that modeling of the resonator and filter response using 1D electro-acoustic simulation (1,2) which includes losses is essential to extract acoustic and electrical material parameters. (1) Solidly Mounted Bulk Acoustic Wave Filters for the Ghz Frequency Range, H.P. Loebl, C. Metzmacher , D.N.Peligrad , R. Mauczok , M. Klee , W. Brand , R.F. Milsom , P.Lok , F.van Straten , A. Tuinhout , J.W.Lobeek, IEEE 2002 Ultrasonics Symposium Munich, October 2002. (2) Combined Acoustic-Electromagnetic Simulation Of Thin-Film Bulk Acoustic Wave Filters, R.F. Milsom, H-P. Löbl, D.N. Peligrad, J-W. Lobeek, A. Tuinhout, R. H. ten Dolle IEEE 2002 Ultrasonics Symposium Munich, October 2002.
Directory of Open Access Journals (Sweden)
Francisco J. Baldenebro-Lopez
2015-01-01
Full Text Available In this work, the mechanical properties and microstructural features of an AISI 304L stainless steel in two presentations, bulk and fibers, were systematically studied in order to establish the relationship among microstructure, mechanical properties, manufacturing process and effect on sample size. The microstructure was analyzed by XRD, SEM and TEM techniques. The strength, Young’s modulus and elongation of the samples were determined by tensile tests, while the hardness was measured by Vickers microhardness and nanoindentation tests. The materials have been observed to possess different mechanical and microstructural properties, which are compared and discussed.
Extraordinary plasticity of ductile bulk metallic glasses.
Chen, Mingwei; Inoue, Akihisa; Zhang, Wei; Sakurai, Toshio
2006-06-23
Shear bands generally initiate strain softening and result in low ductility of metallic glasses. In this Letter, we report high-resolution electron microscope observations of shear bands in a ductile metallic glass. Strain softening caused by localized shearing was found to be effectively prevented by nanocrystallization that is in situ produced by plastic flow within the shear bands, leading to large plasticity and strain hardening. These atomic-scale observations not only well explain the extraordinary plasticity that was recently observed in some bulk metallic glasses, but also reveal a novel deformation mechanism that can effectively improve the ductility of monolithic metallic glasses.
"Work-Hardenable" ductile bulk metallic glass.
Das, Jayanta; Tang, Mei Bo; Kim, Ki Buem; Theissmann, Ralf; Baier, Falko; Wang, Wei Hua; Eckert, Jürgen
2005-05-27
Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (glass, which exhibits high strength of up to 2265 MPa together with extensive "work hardening" and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The "work-hardening" capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.
Towards bulk based preconditioning for quantum dotcomputations
Energy Technology Data Exchange (ETDEWEB)
Dongarra, Jack; Langou, Julien; Tomov, Stanimire; Channing,Andrew; Marques, Osni; Vomel, Christof; Wang, Lin-Wang
2006-05-25
This article describes how to accelerate the convergence of Preconditioned Conjugate Gradient (PCG) type eigensolvers for the computation of several states around the band gap of colloidal quantum dots. Our new approach uses the Hamiltonian from the bulk materials constituent for the quantum dot to design an efficient preconditioner for the folded spectrum PCG method. The technique described shows promising results when applied to CdSe quantum dot model problems. We show a decrease in the number of iteration steps by at least a factor of 4 compared to the previously used diagonal preconditioner.
Improving the bulk data transfer experience
Energy Technology Data Exchange (ETDEWEB)
Guok, Chin; Guok, Chin; Lee, Jason R.; Berket, Karlo
2008-05-07
Scientific computations and collaborations increasingly rely on the network to provide high-speed data transfer, dissemination of results, access to instruments, support for computational steering, etc. The Energy Sciences Network is establishing a science data network to provide user driven bandwidth allocation. In a shared network environment, some reservations may not be granted due to the lack of available bandwidth on any single path. In many cases, the available bandwidth across multiple paths would be sufficient to grant the reservation. In this paper we investigate how to utilize the available bandwidth across multiple paths in the case of bulk data transfer.
Binary Ni-Nb bulk metallic glasses
Xia, L.; Li, W. H.; Fang, S. S.; Wei, B. C.; Dong, Y. D.
2006-01-01
We studied the glass forming ability of Ni-Nb binary alloys and found that some of the alloys can be prepared into bulk metallic glasses by a conventional Cu-mold casting. The best glass former within the compositional range studied is off-eutectic Ni62Nb38 alloy, which is markedly different from those predicted by the multicomponent and deep eutectic rules. The glass formation mechanism for binary Ni-Nb alloys was studied from the thermodynamic point of view and a parameter γ* was proposed to approach the ability of glass formation against crystallization.
Cosmological Brane World Solutions with Bulk Scalar Fields
Davis, Stephen C.
2001-01-01
Cosmological brane world solutions are found for five-dimensional bulk spacetimes with a scalar field. A supergravity inspired method for obtaining static solutions is combined with a method for finding brane cosmologies with constant bulk energies. This provides a way to generate full (bulk and brane) cosmological solutions to brane worlds with bulk scalar fields. Examples of these solutions, and their cosmological evolution, are discussed.
Energy Technology Data Exchange (ETDEWEB)
Liu, C H; Li, J; Singh, M; Larin, K V [Department of Biomedical Engineering, University of Houston, Houston, Texas (United States); Skryabina, M N [Department of Physics, M.V. Lomonosov Moscow State University (Russian Federation); Sobol, E N [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)
2014-08-31
The development of an effective system to monitor the changes in the elastic properties of cartilage tissue with increasing temperature in laser reconstruction is an urgent practical task. In this paper, the use of phase-sensitive optical coherence elastography for detection of elastic waves in the sample has allowed Young's modulus of cartilage tissue to be measured directly during heating. Young's modulus was calculated from the group velocity of propagation of elastic waves excited by means of a system supplying focused air pulses. The measurement results are in agreement with the results of measurements of the modulus of elasticity under mechanical compression. The technique developed allows for noninvasive measurements; its development is promising for the use in vivo. (laser biophotonics)
Zare, Yasser
2017-01-15
The effect of percolation threshold on the mechanical properties of insulate polymer nanocomposites has been briefly investigated in literature. In this work, an approach is suggested to study the percolation threshold and interphase role in polymer/clay nanocomposites (PCN) by a model for tensile modulus. The percolation threshold is related to the aspect ratio of clay layers and the predictions of the suggested methodology are compared with the experimental data. A low percolation threshold is obtained by high aspect ratio of clay layers which increases the modulus. Also, the developed model suggests the accurate results compared to experimental data assuming the interphase role. According to the calculations, the best modulus of PCN is achieved by the thinnest clay layers and the thickest interphase between polymer and clay. Copyright © 2016. Published by Elsevier Inc.
Energy Technology Data Exchange (ETDEWEB)
Berdova, Maria; Liu, Xuwen; Franssila, Sami, E-mail: sami.franssila@aalto.fi [Department of Materials Science and Engineering, Aalto University, 02150 Espoo (Finland); Wiemer, Claudia; Lamperti, Alessio; Tallarida, Grazia; Cianci, Elena [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Fanciulli, Marco [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB), Italy and Dipartimento di Scienza dei Materiali, Università degli studi di Milano Bicocca, 20126 Milano (Italy)
2016-09-15
The investigation of mechanical properties of atomic layer deposition HfO{sub 2} films is important for implementing these layers in microdevices. The mechanical properties of films change as a function of composition and structure, which accordingly vary with deposition temperature and post-annealing. This work describes elastic modulus, hardness, and wear resistance of as-grown and annealed HfO{sub 2}. From nanoindentation measurements, the elastic modulus and hardness remained relatively stable in the range of 163–165 GPa and 8.3–9.7 GPa as a function of deposition temperature. The annealing of HfO{sub 2} caused significant increase in hardness up to 14.4 GPa due to film crystallization and densification. The structural change also caused increase in the elastic modulus up to 197 GPa. Wear resistance did not change as a function of deposition temperature, but improved upon annealing.
19 CFR 151.24 - Unlading facilities for bulk sugar.
2010-04-01
... 19 Customs Duties 2 2010-04-01 2010-04-01 false Unlading facilities for bulk sugar. 151.24 Section... OF THE TREASURY (CONTINUED) EXAMINATION, SAMPLING, AND TESTING OF MERCHANDISE Sugars, Sirups, and Molasses § 151.24 Unlading facilities for bulk sugar. When dutiable sugar is to be imported in bulk, a full...
Guz, Nataliia; Dokukin, Maxim; Kalaparthi, Vivekanand; Sokolov, Igor
2014-01-01
Here we investigated the question whether cells, being highly heterogeneous objects, could be described with the elastic modulus (effective Young’s modulus) in a self-consistent way. We performed a comparative analysis of the elastic modulus derived from the indentation data obtained with atomic force microscopy (AFM) on human cervical epithelial cells (both normal and cancerous). Both sharp (cone) and dull (2500-nm radius sphere) AFM probes were used. The indentation data were processed through different elastic models. The cell was approximated as a homogeneous elastic medium that had either 1), smooth hemispherical boundary (Hertz/Sneddon models) or 2), the boundary covered with a layer of glycocalyx and membrane protrusions (“brush” models). Consistency of these approximations was investigated. Specifically, we tested the independence of the elastic modulus of the indentation depth, which is assumed in these models. We demonstrated that only one model showed consistency in treating cells as a homogeneous elastic medium, namely, the brush model, when processing the indentation data collected with the dull AFM probe. The elastic modulus demonstrated strong depth dependence in all models: Hertz/Sneddon models (no brush taken into account), and when the brush model was applied to the data collected with sharp conical probes. We conclude that it is possible to describe the elastic properties of the cell body by means of an effective elastic modulus, used in a self-consistent way, when using the brush model to analyze data collected with a dull AFM probe. The nature of these results is discussed. PMID:25099796
Bindo, Márcio José Fraxino; Nakamae, Atlas Edson Moleros; Santos, Lydia de Brito; Ishikawa, Karin Hitomi; Guarnieri, Tatiana de Carvalho; Tamaki, Regina
2009-01-01
The aim of this study was to evaluate the following acrylic resins: Clássico, QC-20 and Lucitone, recommended specifically for thermal polymerization, and Acron MC and VIPI-WAVE, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.
Microhardness and Young's modulus of high burn-up UO{sub 2} fuel
Energy Technology Data Exchange (ETDEWEB)
Cappia, F. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany); Technische Universität München, Faculty of Mechanical Engineering, Department of Nuclear Engineering, D-85748, Garching bei München (Germany); Pizzocri, D. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany); Politecnico di Milano, Department of Energy, Nuclear Engineering Division, 20156, Milano (Italy); Marchetti, M. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany); Université Montpellier 2, Institut d’Electronique du Sud UMR CNRS 5214, 34095, Montpellier (France); Schubert, A.; Van Uffelen, P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany); Luzzi, L. [Politecnico di Milano, Department of Energy, Nuclear Engineering Division, 20156, Milano (Italy); Papaioannou, D. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany); Macián-Juan, R. [Technische Universität München, Faculty of Mechanical Engineering, Department of Nuclear Engineering, D-85748, Garching bei München (Germany); Rondinella, V.V., E-mail: Vincenzo.RONDINELLA@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125, Karlsruhe (Germany)
2016-10-15
Vickers microhardness (HV{sub 0.1}) and Young's modulus (E) measurements of LWR UO{sub 2} fuel at burn-up ≥60 GWd/tHM are presented. Their ratio HV{sub 0.1}/E was found constant in the range 60–110 GWd/tHM. From the ratio and the microhardness values vs porosity, the Young's modulus dependence on porosity was derived and extended to the full radial profile, including the high burn-up structure (HBS). The dependence is well represented by a linear correlation. The data were compared to fuel performance codes correlations. A burn-up dependent factor was introduced in the Young's modulus expression. The modifications extend the experimental validation range of the TRANSURANUS correlation from un-irradiated to irradiated UO{sub 2} and up to 20% porosity. First simulations of LWR fuel rod irradiations were performed in order to illustrate the impact on fuel performance. In the specific cases selected, the simulations suggest a limited effect of the Young's modulus decrease due to burn-up on integral fuel performance. - Highlights: • Vickers microhardness and Young's modulus data of high burnup fuels are presented. • The data are compared to fuel performance codes' correlations. • A burn-up dependent factor is introduced for the Young's modulus of irradiated fuel. • The modification extends ranges of experimental validation of the code correlation. • The new burn-up dependent factor has limited effect on integral fuel performance.
2014-08-01
The University of New Orleans Transportation Institute was tasked by the Louisiana Transportation Research Center (LTRC) in mid-2012 to assess the use of containers to transport bulk and break bulk commodities and to determine what their impact would...
CSIR Research Space (South Africa)
Anochie-Boateng, Joseph
2010-11-01
Full Text Available -1 Technical Paper ISSN 1997-1400 Int. J. Pavement Res. Technol. 3(6):286-294 Copyright @ Chinese Society of Pavement Engineering Vol.3 No.6 Nov. 2010 International..., Alberta, Canada. 18. AASHTO, (2005). Standard Method of Test for Bulk Specific Gravity of Compacted Hot Mix Asphalt (HMA) Using Saturated Surface-Dry Specimens, AASHTO T 166, AASHTO, USA. 19. AASHTO, (2009). Standard Method of Test for Theoretical...
Bulk magnetic domain stability controls paleointensity fidelity
Paterson, Greig A.; Muxworthy, Adrian R.; Yamamoto, Yuhji; Pan, Yongxin
2017-12-01
Nonideal, nonsingle-domain magnetic grains are ubiquitous in rocks; however, they can have a detrimental impact on the fidelity of paleomagnetic records—in particular the determination of ancient magnetic field strength (paleointensity), a key means of understanding the evolution of the earliest geodynamo and the formation of the solar system. As a consequence, great effort has been expended to link rock magnetic behavior to paleointensity results, but with little quantitative success. Using the most comprehensive rock magnetic and paleointensity data compilations, we quantify a stability trend in hysteresis data that characterizes the bulk domain stability (BDS) of the magnetic carriers in a paleomagnetic specimen. This trend is evident in both geological and archeological materials that are typically used to obtain paleointensity data and is therefore pervasive throughout most paleomagnetic studies. Comparing this trend to paleointensity data from both laboratory and historical experiments reveals a quantitative relationship between BDS and paleointensity behavior. Specimens that have lower BDS values display higher curvature on the paleointensity analysis plot, which leads to more inaccurate results. In-field quantification of BDS therefore reflects low-field bulk remanence stability. Rapid hysteresis measurements can be used to provide a powerful quantitative method for preselecting paleointensity specimens and postanalyzing previous studies, further improving our ability to select high-fidelity recordings of ancient magnetic fields. BDS analyses will enhance our ability to understand the evolution of the geodynamo and can help in understanding many fundamental Earth and planetary science questions that remain shrouded in controversy.
Boundary-bulk relation in topological orders
Directory of Open Access Journals (Sweden)
Liang Kong
2017-09-01
Full Text Available In this paper, we study the relation between an anomaly-free n+1D topological order, which are often called n+1D topological order in physics literature, and its nD gapped boundary phases. We argue that the n+1D bulk anomaly-free topological order for a given nD gapped boundary phase is unique. This uniqueness defines the notion of the “bulk” for a given gapped boundary phase. In this paper, we show that the n+1D “bulk” phase is given by the “center” of the nD boundary phase. In other words, the geometric notion of the “bulk” corresponds precisely to the algebraic notion of the “center”. We achieve this by first introducing the notion of a morphism between two (potentially anomalous topological orders of the same dimension, then proving that the notion of the “bulk” satisfies the same universal property as that of the “center” of an algebra in mathematics, i.e. “bulk = center”. The entire argument does not require us to know the precise mathematical description of a (potentially anomalous topological order. This result leads to concrete physical predictions.
Substantial bulk photovoltaic effect enhancement via nanolayering
Wang, Fenggong; Young, Steve M.; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M.
2016-01-01
Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials' responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1-x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. This opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition.
Perovskite oxides: Oxygen electrocatalysis and bulk structure
Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, Ernest
1987-01-01
Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.
A Fiber-Coupled Self-Mixing Laser Diode for the Measurement of Young’s Modulus
Directory of Open Access Journals (Sweden)
Ke Lin
2016-06-01
Full Text Available This paper presents the design of a fiber-coupled self-mixing laser diode (SMLD for non-contact and non-destructive measurement of Young’s modulus. By the presented measuring system, the Young’s modulus of aluminum 6061 and brass are measured as 70.0 GPa and 116.7 GPa, respectively, showing a good agreement within the standards in the literature and yielding a much smaller deviation and a higher repeatability compared with traditional tensile testing. Its fiber-coupled characteristics make the system quite easy to be installed in many application cases.
Youssef, Hamdy M.; El-Bary, Alaa A.
2017-09-01
This work is concerning with the study of the thermoelastic damping of a nanobeam resonator in the context of the two-temperature generalized thermoelasticity theory. An explicit formula of thermoelastic damping has been derived when Young's modulus is a function of the reference temperature. Influences of the beam height and Young's modulus have been studied with some comparisons between the Biot model and the Lord-Shulman model (L-S) for one- and two-temperature types. Numerical results show that the values of the thermal relaxation parameter and the two-temperature parameter have a strong influence on thermoelastic damping at nanoscales.
Li, Hai-xia; Zare, Yasser; Rhee, Kyong Yop
2017-09-01
The Tandon-Weng expression of the Mori-Tanaka theory comprises some complex terms for estimating Young's modulus in composites, which limit its application to polymer nanocomposites. In this article, this model is simplified for clay/polymer nanocomposites (CPNs). The original model demonstrates that the Poisson ratio and modulus of the matrix, as well as the aspect ratio, modulus, and concentration of the filler, play chief roles in determining the modulus. However, the simplified Tandon-Weng model shows that some parameters, such as the modulus of nanoparticles, do not affect the modulus of CPNs. The moduli calculated by the simplified model are compared with experimental measurements of several samples as well as to predictions made by other known models (e.g., the Halpin-Tsai model).
2010-06-17
... IAEA International Atomic Energy Agency IMDG Code International Maritime Dangerous Goods Code IMO... authorized for bulk transportation by vessel and include special handling procedures based on the IMSBC Code... Management Facility (M-30), U.S. Department of Transportation, West Building Ground Floor, Room W12-140, 1200...
Static modulus of elasticity of concrete measured by the ultrasonic method
Directory of Open Access Journals (Sweden)
Sena Rodrigues, S.
2003-12-01
Full Text Available Lately, a huge number of accidents caused by problems found in the durability of concrete structures due to inappropriate project design, lack of control of quality during the project s execution, inadequate maintenance practices and an aggressive environment has been reported. This finding has required from the professionals constant inspections and evaluations of the real conditions of all concrete structures. In order to perform those inspections, one should know not only the elastic modulus to analyze the concrete structural behaviour but also to investigate its performance, since the strains may yield cracks able to compromise the durability- of structures. Non-destructive testing techniques, particularly the ultrasonic testing, are performed to evaluate and determine the quality of a concrete structure or element. Currently, such essays have been widely researched and analyzed all over the world because they enable the examination of structures without damaging them. The purpose of the present study was to correlate the ultrasonic pulse velocity and the elastic modulus of several concrete specimens molded with a range of water-cement ratios, different kinds of aggregates and curing methods. All the concrete specimens were tested in different ages to determine the pulse velocity and the static modulus of elasticity standardized according to KBR 8522, through mechanical extensometers, electrical strain gauge and LVTD inductive transducer.
Recientemente se ha registrado un gran número de accidentes causados por problemas relacionados con la durabilidad de las estructuras de hormigón y debidos a un inadecuado proyecto de diseño, ausencia de control de calidad durante la ejecución del proyecto, prácticas inadecuadas de construcción y un ambiente agresivo. Este hallazgo ha dado lugar a que los ingenieros realicen constantes inspecciones y evaluaciones de la condición real de todas las estructuras de hormigón. Para llevar a cabo
Contributions crumb rubber in hot mix asphalt to the resilient modulus
Ariyapijati, Raden Hendra; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal
2017-06-01
Pavement on the structure of the surface layer receives direct load from the vehicles. Road surfaces are designed to withstand the wear from vehicle loads. Therefore, we need a way to improve the durability of the pavement. Road damage may reduce the life of roads and increase the maintenance costs. The retention rate of road surface material is affected by the environmental conditions, one of them is temperature. To overcome the issues related to temperature, material additives are added to the asphalt mixture. These additive materials would change the binding properties of bitumen and the characteristics of strain and stress before the damage due to repeated traffic loading. Crumb rubber (CR) is a type of polymer additives and thermoplastic elastomers are obtained from scrap tires and rubber waste that is utilized in order to preserve the environment. This study investigated the contribution of the crumb rubber in terms of the value of resilient modulus and resistance to deformation. Hot mix asphalt used was asphalt Pen 60/70, coarse aggregate, fine aggregate and filler. Crumb rubber was made from scrap tire rubber, in the form of fine powder with sieve no. 30 (0.6 mm). CR additive was added to the base asphalt at several rates of 5%, 10%, 15%, and 20% at a temperature of 177° C. The test data used the indirect tensile test with a tool UMATTA at temperatures of 25°, 35°, and 45° C. The test results showed that the levels of crumb rubber on the asphalt decreased the penetration rate, increased the bitumen softening point, and improved the resistance to permanent deformation. The addition of additive materials was evidenced to improve the penetration index, reduce the temperature sensitivity, and increase the viscosity. Subsequently, it can extend the temperature range of viscoelasticity. The contributions of crumb rubber in hot mix asphalt included the increase of the recoverable deformation and the decrease of the value of resilient modulus. This study
Diffusion and bulk flow in phloem loading
DEFF Research Database (Denmark)
Dölger, Julia; Rademaker, Hanna; Liesche, Johannes
2014-01-01
diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across......%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all...... of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10...
Organoboron polymers for photovoltaic bulk heterojunctions.
Cataldo, Sebastiano; Fabiano, Simone; Ferrante, Francesco; Previti, Francesco; Patanè, Salvatore; Pignataro, Bruno
2010-07-15
We report on the application of three-coordinate organoboron polymers, inherently strong electron acceptors, in flexible photovoltaic (PV) cells. Poly[(1,4-divinylenephenylene)(2,4,6-triisopropylphenylborane)] (PDB) has been blended with poly(3-hexylthiophene-2,5-diyl) (P3HT) to form a thin film bulk heterojunction (BHJ) on PET/ITO substrates. Morphology may be modulated to give a high percentage of domains (10-20 nm in size) allowing exciton separation. The photoelectric properties of the BHJs in devices with aluminium back electrodes were imaged by light beam induced current (LBIC) and light beam induced voltage (LBIV) techniques. Open circuit voltages, short circuit currents and overall external quantum efficiencies obtained are among the highest reported for all-polymer PV cells. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A route to transparent bulk metals
Schwingenschlögl, Udo
2012-07-23
Hypothetical compounds based on a sapphire host are investigated with respect to their structural as well as electronic features. The results are obtained by electronic structure calculations within density functional theory and the generalized gradient approximation. A quarter of the Al atoms in Al 2O 3 is replaced by a 4d transition metal M ion, with d 0 to d 9 electronic configuration. We perform structure optimizations for all the compounds and analyze the electronic states. Due to the sizeable band gap of the Al 2O 3 host, we can identify promising candidates for transparent bulk metals. We explain the mechanisms leading to this combination of materials properties. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Holographic bulk viscosity: GPR vs EO
Buchel, Alex; Kiritsis, Elias
2011-01-01
Recently Eling and Oz (EO) proposed a formula for the holographic bulk viscosity, in arXiv:1103.1657, derived from the null horizon focusing equation. This formula seems different from that obtained earlier by Gubser, Pufu and Rocha (GPR) in arXiv:0806.0407 calculated from the IR limit of the two-point function of the trace of the stress tensor. The two were shown to agree only for some simple scaling cases. We point out that the two formulae agree in two non-trivial holographic theories describing RG flows. The first is the strongly coupled N=2* gauge theory plasma. The second is the semi-phenomenological model of Improved Holographic QCD.
Tuneable film bulk acoustic wave resonators
Gevorgian, Spartak Sh; Vorobiev, Andrei K
2013-01-01
To handle many standards and ever increasing bandwidth requirements, large number of filters and switches are used in transceivers of modern wireless communications systems. It makes the cost, performance, form factor, and power consumption of these systems, including cellular phones, critical issues. At present, the fixed frequency filter banks based on Film Bulk Acoustic Resonators (FBAR) are regarded as one of the most promising technologies to address performance -form factor-cost issues. Even though the FBARs improve the overall performances the complexity of these systems remains high. Attempts are being made to exclude some of the filters by bringing the digital signal processing (including channel selection) as close to the antennas as possible. However handling the increased interference levels is unrealistic for low-cost battery operated radios. Replacing fixed frequency filter banks by one tuneable filter is the most desired and widely considered scenario. As an example, development of the softwa...
Interface control of bulk ferroelectric polarization
Energy Technology Data Exchange (ETDEWEB)
Yu, P [University of California, Berkeley; Luo, Weidong [ORNL; Yi, D. [University of California, Berkeley; Zhang, J.-X. [University of California, Berkeley; Rossell, M.D. [Lawrence Berkeley National Laboratory (LBNL); Yang, C.-H. [Korea Advanced Institute of Science and Technology; You, L. [University of California, Berkeley; Singh-Bhalla, G. B. [University of California, Berkeley & LBNL; Yang, S.Y [University of California, Berkeley; He, Q [University of California, Berkeley; Ramasse, Q. M. [Lawrence Berkeley National Laboratory (LBNL); Erni, R. [Lawrence Berkeley National Laboratory (LBNL); Martin, L. W. [University of Illinois, Urbana-Champaign; Chu, Y. H. [University of California, Berkeley; Pantelides, Sokrates T [ORNL; Pennycook, Stephen J [ORNL; Ramesh, R. [University of California, Berkeley
2012-01-01
The control of material interfaces at the atomic level has led to no- vel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we em- ploy a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectric hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite un- derlayers extends the generality of this phenomenon.