The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Dean L. Preston - One of the best experts on this subject based on the ideXlab platform.
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More on Shear Modulus collapse of lattices at high pressure
Solid State Communications, 2006Co-Authors: Leonid Burakovsky, Carl W. Greef, Dean L. PrestonAbstract:Abstract In his recent paper, Shear Modulus collapse of lattices at high pressure, J. Phys. Cond. Matt. 16 (2004) L125, V.V. Kechin claims that the zero temperature Shear Modulus of a metallic solid vanishes at a high critical pressure, and the critical pressures for this Shear Modulus collapse lie in the range 0–250 Mbar for elemental metals. Here we demonstrate that Kechin's arguments contain an erroneous assumption, and therefore, do not prove that all metals become mechanically unstable at high pressures. Ab initio calculations and experimental results on a number of solids are analyzed to confirm our conclusion.
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Generalized guinan-steinberg formula for the Shear Modulus at all pressures
Physical Review B, 2005Co-Authors: Leonid Burakovsky, Dean L. PrestonAbstract:The Guinan-Steinberg (GS) formula for the Shear Modulus at all pressures is widely used in material strength studies. As we demonstrate here, the GS formula predicts a value for the Shear Modulus that is higher than its actual value at low to moderate compressions, even if it has the correct ultrahigh-pressure limit. We show that the reason for this shortcoming is insufficient negative curvature in the GS Shear Modulus as a function of pressure and propose a generalized GS formula that is accurate at all pressures.
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Analytic model of the Shear Modulus at all temperatures and densities
Physical Review B, 2003Co-Authors: Leonid Burakovsky, Carl Greeff, Dean L. PrestonAbstract:An analytic model of the Shear Modulus applicable at temperatures up to melt and at all densities is presented. It is based in part on a relation between the melting temperature and the Shear Modulus at melt. Experimentaldata on argon are shown to agree with this relation to within 1%. The model of the Shear Modulus involves seven parameters, all of which can be determined from zero-pressure experimental data. We obtain the values of these parameters for 11 elemental solids. Both the experimental data on the room-temperature Shear Modulus of argon to compressions of ∼2.5, and theoretical calculations of the zero-temperature Shear Modulus of aluminum to compressions of ∼3.5 are in good agreement with the model. Electronic-structure calculations of the Shear moduli of copper and gold to compressions of 2, performed by us, agree with the model to within uncertainties.
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A model of the Shear Modulus
Solid State Communications, 1992Co-Authors: Dean L. Preston, Duane C. WallaceAbstract:The Shear Modulus is modeled at all temperatures and densities. Parameters are provided for twenty-two metals.
Leonid Burakovsky - One of the best experts on this subject based on the ideXlab platform.
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More on Shear Modulus collapse of lattices at high pressure
Solid State Communications, 2006Co-Authors: Leonid Burakovsky, Carl W. Greef, Dean L. PrestonAbstract:Abstract In his recent paper, Shear Modulus collapse of lattices at high pressure, J. Phys. Cond. Matt. 16 (2004) L125, V.V. Kechin claims that the zero temperature Shear Modulus of a metallic solid vanishes at a high critical pressure, and the critical pressures for this Shear Modulus collapse lie in the range 0–250 Mbar for elemental metals. Here we demonstrate that Kechin's arguments contain an erroneous assumption, and therefore, do not prove that all metals become mechanically unstable at high pressures. Ab initio calculations and experimental results on a number of solids are analyzed to confirm our conclusion.
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Generalized guinan-steinberg formula for the Shear Modulus at all pressures
Physical Review B, 2005Co-Authors: Leonid Burakovsky, Dean L. PrestonAbstract:The Guinan-Steinberg (GS) formula for the Shear Modulus at all pressures is widely used in material strength studies. As we demonstrate here, the GS formula predicts a value for the Shear Modulus that is higher than its actual value at low to moderate compressions, even if it has the correct ultrahigh-pressure limit. We show that the reason for this shortcoming is insufficient negative curvature in the GS Shear Modulus as a function of pressure and propose a generalized GS formula that is accurate at all pressures.
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Analytic model of the Shear Modulus at all temperatures and densities
Physical Review B, 2003Co-Authors: Leonid Burakovsky, Carl Greeff, Dean L. PrestonAbstract:An analytic model of the Shear Modulus applicable at temperatures up to melt and at all densities is presented. It is based in part on a relation between the melting temperature and the Shear Modulus at melt. Experimentaldata on argon are shown to agree with this relation to within 1%. The model of the Shear Modulus involves seven parameters, all of which can be determined from zero-pressure experimental data. We obtain the values of these parameters for 11 elemental solids. Both the experimental data on the room-temperature Shear Modulus of argon to compressions of ∼2.5, and theoretical calculations of the zero-temperature Shear Modulus of aluminum to compressions of ∼3.5 are in good agreement with the model. Electronic-structure calculations of the Shear moduli of copper and gold to compressions of 2, performed by us, agree with the model to within uncertainties.
Alexander V. Balatsky - One of the best experts on this subject based on the ideXlab platform.
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Shear Modulus in Viscoelastic Solid 4He
Journal of Low Temperature Physics, 2010Co-Authors: Matthias J. Graf, Alexander V. BalatskyAbstract:The complex Shear Modulus of solid 4He exhibits an anomaly in the same temperature region where torsion oscillators show a change in period. We propose that the observed stiffening of the Shear Modulus with decreasing temperature can be well described by the response of glassy components inside of solid 4He. Since glass is an anelastic material, we utilize the viscoelastic approach to describe its dynamics. The viscoelastic component possesses an increasing relaxation as temperature decreases. The response functions thus derived are identical to those obtained for a glassy, time-delayed restoring back-action. By generalizing the viscoelastic equations for stress and strain to a multiphase system of constituents, composed of patches with different damping and relaxation properties, we predict that the maximum change of the magnitude of the Shear Modulus and the maximum height of the dissipation peak are independent of an applied external frequency. The same response expressions allow us to calculate the temperature dependence of the Shear Modulus’ amplitude and dissipation. Finally, we demonstrate that a Vogel-Fulcher-Tammann (VFT) relaxation time is in agreement with available experimental data.
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Glass anomaly in the Shear Modulus of solid 4He.
Physical review letters, 2010Co-Authors: Matthias J. Graf, Alexander V. BalatskyAbstract:The Shear Modulus of solid H 4 e exhibits an anomalous increase at low temperatures that behaves qualitatively similar to the frequency change in torsional oscillator experiments. We propose that this stiffening of the Shear Modulus with decreasing temperature can be described with a glass susceptibility assuming a temperature-dependent relaxation time τ(T). Below a characteristic crossover temperature T x , where ωτ-(T x ) ∼ 1, a significant slowing down of dynamics leads to an increase in the Shear Modulus. We predict that the maximum change of the amplitude of the Shear Modulus and the height of the dissipation peak are independent of the applied frequency ω. Our calculations also show a qualitative difference in behavior of the Shear Modulus depending on the temperature dependence of τ(T).
Ali Pak - One of the best experts on this subject based on the ideXlab platform.
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Small-Strain Shear Modulus of Cement-Admixed Kaolinite
Geotechnical and Geological Engineering, 2011Co-Authors: M. Bahador, Ali PakAbstract:An experimental study is conducted to measure small-strain Shear Modulus of clay-cement mixture using bender element apparatus setup in a triaxial cell. Bender element tests were conducted on cement-treated soils and the results were analyzed to study the variation of Shear Modulus properties of soil specimens at different cement contents, confining pressures, curing times, and compaction moisture contents. Based on the obtained results increasing the cement ratio has a significant effect on the small-strain Shear Modulus of the treated soils, and this effect signifies with increasing the moisture content and curing time. Rates of Shear Modulus enhancements due to cement content, curing time, and compaction moisture content are quantified and presented. In this study, a clay–cement–water ratio formulation is proposed that enables one to calculate cement and water contents required to obtain specific small-strain Shear Modulus.
Matthias J. Graf - One of the best experts on this subject based on the ideXlab platform.
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Shear Modulus in Viscoelastic Solid 4He
Journal of Low Temperature Physics, 2010Co-Authors: Matthias J. Graf, Alexander V. BalatskyAbstract:The complex Shear Modulus of solid 4He exhibits an anomaly in the same temperature region where torsion oscillators show a change in period. We propose that the observed stiffening of the Shear Modulus with decreasing temperature can be well described by the response of glassy components inside of solid 4He. Since glass is an anelastic material, we utilize the viscoelastic approach to describe its dynamics. The viscoelastic component possesses an increasing relaxation as temperature decreases. The response functions thus derived are identical to those obtained for a glassy, time-delayed restoring back-action. By generalizing the viscoelastic equations for stress and strain to a multiphase system of constituents, composed of patches with different damping and relaxation properties, we predict that the maximum change of the magnitude of the Shear Modulus and the maximum height of the dissipation peak are independent of an applied external frequency. The same response expressions allow us to calculate the temperature dependence of the Shear Modulus’ amplitude and dissipation. Finally, we demonstrate that a Vogel-Fulcher-Tammann (VFT) relaxation time is in agreement with available experimental data.
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Glass anomaly in the Shear Modulus of solid 4He.
Physical review letters, 2010Co-Authors: Matthias J. Graf, Alexander V. BalatskyAbstract:The Shear Modulus of solid H 4 e exhibits an anomalous increase at low temperatures that behaves qualitatively similar to the frequency change in torsional oscillator experiments. We propose that this stiffening of the Shear Modulus with decreasing temperature can be described with a glass susceptibility assuming a temperature-dependent relaxation time τ(T). Below a characteristic crossover temperature T x , where ωτ-(T x ) ∼ 1, a significant slowing down of dynamics leads to an increase in the Shear Modulus. We predict that the maximum change of the amplitude of the Shear Modulus and the height of the dissipation peak are independent of the applied frequency ω. Our calculations also show a qualitative difference in behavior of the Shear Modulus depending on the temperature dependence of τ(T).
