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J Van Humbeeck - One of the best experts on this subject based on the ideXlab platform.
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anelasticity of b19 martensitic phase in ni ti and ni ti cu alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: K Sapozhnikov, S Golyandin, S Kustov, R Schaller, J Van HumbeeckAbstract:Abstract Anelastic properties of the B19′ martensitic phase have been studied in two polycrystalline alloys: Ni Ti with nearly equiatomic composition and Ni Ti Cu (about 49 at.% Ti, 46 at.% Ni, and 5 at.% Cu). Internal Friction, Dynamic shear modulus and torsional strain at zero applied stress were measured in a forced torsion pendulum for strain amplitudes of 2 × 10 −5 to 2 × 10 −4 , temperatures of 6–300 K, temperature change rates of 1–5 K/min and frequencies of 0.001–10 Hz. Several peculiarities have been found during thermal cycling: dependence of the internal Friction on the temperature change rate and frequency of oscillation, which disappears with isothermal exposure, temperature hysteresis of the internal Friction and Dynamic shear modulus, and low-temperature anomalies in the temperature dependence of the Dynamic shear modulus. The observed peculiarities result from reversible microplastic straining of the martensitic phase under the action of thermal stresses arising from anisotropy of thermal expansion of the B19′ phase. A relaxation peak in internal Friction has been found in both alloys at temperatures of about 200 K. The temperature and the shape of the peak are influenced by the thermal stresses. The activation enthalpy of the relaxation has been evaluated both in isothermal and in nonisothermal conditions.
K Sapozhnikov - One of the best experts on this subject based on the ideXlab platform.
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anelasticity of b19 martensitic phase in ni ti and ni ti cu alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: K Sapozhnikov, S Golyandin, S Kustov, R Schaller, J Van HumbeeckAbstract:Abstract Anelastic properties of the B19′ martensitic phase have been studied in two polycrystalline alloys: Ni Ti with nearly equiatomic composition and Ni Ti Cu (about 49 at.% Ti, 46 at.% Ni, and 5 at.% Cu). Internal Friction, Dynamic shear modulus and torsional strain at zero applied stress were measured in a forced torsion pendulum for strain amplitudes of 2 × 10 −5 to 2 × 10 −4 , temperatures of 6–300 K, temperature change rates of 1–5 K/min and frequencies of 0.001–10 Hz. Several peculiarities have been found during thermal cycling: dependence of the internal Friction on the temperature change rate and frequency of oscillation, which disappears with isothermal exposure, temperature hysteresis of the internal Friction and Dynamic shear modulus, and low-temperature anomalies in the temperature dependence of the Dynamic shear modulus. The observed peculiarities result from reversible microplastic straining of the martensitic phase under the action of thermal stresses arising from anisotropy of thermal expansion of the B19′ phase. A relaxation peak in internal Friction has been found in both alloys at temperatures of about 200 K. The temperature and the shape of the peak are influenced by the thermal stresses. The activation enthalpy of the relaxation has been evaluated both in isothermal and in nonisothermal conditions.
Zili Xu - One of the best experts on this subject based on the ideXlab platform.
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a Friction contact stiffness model of fractal geometry in forced response analysis of a shrouded blade
Nonlinear Dynamics, 2012Co-Authors: Bo Shangguan, Zili XuAbstract:To investigate the nonlinear vibration behavior of a shrouded blade with Friction Dynamic contact interface, a Friction contact stiffness model is proposed to describe the Friction force at different rough interfaces and different normal loads. In the proposed model, the Friction contact interface is discretized to a series of Friction contact pairs and each of them can experience stick, slip, or separate states. Fractal geometry is used to simulate the topography of contact surfaces. The contact stiffness is calculated using the Hertz contact theory and fractal geometry, which is related to contact interfaces parameters including normal load, roughness, Young’s modulus, and Poisson’s ratio. The trajectory tracking method is used to predict the Friction force and it is not necessary to judge the transition condition among stick, slip, and separate states. It is suitable for complicated periodic motion of the contact interfaces. The forced response of a real shrouded blade is predicted using the proposed model and the multi-harmonic balance method. The effect of surface roughness, initial normal load, and contact area on the forced response of a shrouded blade is studied. It is shown that contact stiffness increases with normal load and fractal dimension. The resonant amplitude is sensitive to the initial normal load and contact surface roughness. The response can be influenced by the contact area, which is an important parameter for blade designers.
S Kustov - One of the best experts on this subject based on the ideXlab platform.
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anelasticity of b19 martensitic phase in ni ti and ni ti cu alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: K Sapozhnikov, S Golyandin, S Kustov, R Schaller, J Van HumbeeckAbstract:Abstract Anelastic properties of the B19′ martensitic phase have been studied in two polycrystalline alloys: Ni Ti with nearly equiatomic composition and Ni Ti Cu (about 49 at.% Ti, 46 at.% Ni, and 5 at.% Cu). Internal Friction, Dynamic shear modulus and torsional strain at zero applied stress were measured in a forced torsion pendulum for strain amplitudes of 2 × 10 −5 to 2 × 10 −4 , temperatures of 6–300 K, temperature change rates of 1–5 K/min and frequencies of 0.001–10 Hz. Several peculiarities have been found during thermal cycling: dependence of the internal Friction on the temperature change rate and frequency of oscillation, which disappears with isothermal exposure, temperature hysteresis of the internal Friction and Dynamic shear modulus, and low-temperature anomalies in the temperature dependence of the Dynamic shear modulus. The observed peculiarities result from reversible microplastic straining of the martensitic phase under the action of thermal stresses arising from anisotropy of thermal expansion of the B19′ phase. A relaxation peak in internal Friction has been found in both alloys at temperatures of about 200 K. The temperature and the shape of the peak are influenced by the thermal stresses. The activation enthalpy of the relaxation has been evaluated both in isothermal and in nonisothermal conditions.
S Golyandin - One of the best experts on this subject based on the ideXlab platform.
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anelasticity of b19 martensitic phase in ni ti and ni ti cu alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: K Sapozhnikov, S Golyandin, S Kustov, R Schaller, J Van HumbeeckAbstract:Abstract Anelastic properties of the B19′ martensitic phase have been studied in two polycrystalline alloys: Ni Ti with nearly equiatomic composition and Ni Ti Cu (about 49 at.% Ti, 46 at.% Ni, and 5 at.% Cu). Internal Friction, Dynamic shear modulus and torsional strain at zero applied stress were measured in a forced torsion pendulum for strain amplitudes of 2 × 10 −5 to 2 × 10 −4 , temperatures of 6–300 K, temperature change rates of 1–5 K/min and frequencies of 0.001–10 Hz. Several peculiarities have been found during thermal cycling: dependence of the internal Friction on the temperature change rate and frequency of oscillation, which disappears with isothermal exposure, temperature hysteresis of the internal Friction and Dynamic shear modulus, and low-temperature anomalies in the temperature dependence of the Dynamic shear modulus. The observed peculiarities result from reversible microplastic straining of the martensitic phase under the action of thermal stresses arising from anisotropy of thermal expansion of the B19′ phase. A relaxation peak in internal Friction has been found in both alloys at temperatures of about 200 K. The temperature and the shape of the peak are influenced by the thermal stresses. The activation enthalpy of the relaxation has been evaluated both in isothermal and in nonisothermal conditions.
