The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Eugene M. Terentjev - One of the best experts on this subject based on the ideXlab platform.
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precise determination of the poisson ratio in soft materials with 2d digital image correlation
Soft Matter, 2013Co-Authors: Robyn H. Pritchard, Dimitri Debruyne, Pascal Lava, Eugene M. TerentjevAbstract:In this article, we demonstrate the application of digital image correlation (DIC) in evaluating the strains and Poisson ratio of a range of soft materials in terms of their spatial and temporal resolutions. Homogeneous samples of polydimethylsiloxane (PDMS) elastomer were used as control substance and were measured to have Poisson ratios of 0.498, 0.503, 0.500, and 0.499, in agreement with the reported Incompressible Value of 0.50. Two carbon nanotube (CNT) elastomer composites of identical composition, but one of a homogeneous and the other of a highly inhomogeneous CNT distribution, were used to determine the spatial resolution with good results. The relaxation of a polydomain liquid crystal elastomer (3D-LCE), a cholesteric liquid crystal elastomer (CLCE), and a polyacrylamide gel (PAAm) in water, were used to determine the temporal resolution of the technique. A video at 25 fps was used to evaluate the time dependence of the 3D-LCE over which time an increase in the Poisson ratio was observed. The 3D-LCE relaxes from its initial state at 0.42 to 0.50, converging towards incompressibility at equilibrium. The CLCE was found to have a similar initial Value of 0.44 but converged to ∼0.60, a consequence of its anisotropic elastic nature. PAAm gel relaxation in water was studied over a time period of 7 hours with digital images taken periodically every minute. Its Poisson ratio was found to decrease smoothly from 0.50 to 0.26, with an accompanying reduction in force. The equilibrium result compares well to the 0.25 Value predicted by a theory of the strain-induced swelling of dilute gels. In summary, we find DIC to be a powerful and easy to implement method of accurately measuring local strains in a range of soft materials.
Guo Jin Tang - One of the best experts on this subject based on the ideXlab platform.
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determination of viscoelastic poisson s ratio of solid propellants using an accuracy enhanced 2d digital image correlation technique
Propellants Explosives Pyrotechnics, 2015Co-Authors: Liping Yu, Jieyu Yuan, Zhi Bin Shen, Guo Jin TangAbstract:Poisson’s ratio plays a significant role in the structural response of solid propellants, which is, in essence, a nearly Incompressible viscoelastic material. Numerical models that assume a constant Poisson’s ratio generally cannot achieve good results, thus requiring an accurate knowledge of time-dependent viscoelastic Poisson’s ratio of solid propellants. In this work, accurate determination of tensile strains and viscoelastic Poisson’s ratio of solid propellants using an accuracy-enhanced 2D digital image correlation (DIC) technique is described. To achieve high-accuracy measurement, great improvements were made to regular 2D-DIC technique to maximally eliminate the errors caused by non-ideal loading conditions, specimen deformation and lens distortion. Rigid body translation tests with zero strain state are first performed to verify the accuracy of the proposed DIC technique. Then application of the proposed technique for determining the time-varying viscoelastic Poisson’s ratios of solid propellants in stress relaxation tests are demonstrated. The results reveal that, by adequately eliminating the measurement errors associated with the unavoidable out-of-plane displacements and lens distortion, the present DIC technique can be used for precise determination of viscoelastic Poisson’s ratio of solid propellants, which is found to be increasing nonlinearly to the Incompressible Value of 0.50 as time increases.
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Determination of Viscoelastic Poisson’s Ratio of Solid Propellants using an Accuracy‐enhanced 2D Digital Image Correlation Technique
Propellants Explosives Pyrotechnics, 2015Co-Authors: Bing Pan, Jieyu Yuan, Zhi Bin Shen, Guo Jin TangAbstract:Poisson’s ratio plays a significant role in the structural response of solid propellants, which is, in essence, a nearly Incompressible viscoelastic material. Numerical models that assume a constant Poisson’s ratio generally cannot achieve good results, thus requiring an accurate knowledge of time-dependent viscoelastic Poisson’s ratio of solid propellants. In this work, accurate determination of tensile strains and viscoelastic Poisson’s ratio of solid propellants using an accuracy-enhanced 2D digital image correlation (DIC) technique is described. To achieve high-accuracy measurement, great improvements were made to regular 2D-DIC technique to maximally eliminate the errors caused by non-ideal loading conditions, specimen deformation and lens distortion. Rigid body translation tests with zero strain state are first performed to verify the accuracy of the proposed DIC technique. Then application of the proposed technique for determining the time-varying viscoelastic Poisson’s ratios of solid propellants in stress relaxation tests are demonstrated. The results reveal that, by adequately eliminating the measurement errors associated with the unavoidable out-of-plane displacements and lens distortion, the present DIC technique can be used for precise determination of viscoelastic Poisson’s ratio of solid propellants, which is found to be increasing nonlinearly to the Incompressible Value of 0.50 as time increases.
Robyn H. Pritchard - One of the best experts on this subject based on the ideXlab platform.
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precise determination of the poisson ratio in soft materials with 2d digital image correlation
Soft Matter, 2013Co-Authors: Robyn H. Pritchard, Dimitri Debruyne, Pascal Lava, Eugene M. TerentjevAbstract:In this article, we demonstrate the application of digital image correlation (DIC) in evaluating the strains and Poisson ratio of a range of soft materials in terms of their spatial and temporal resolutions. Homogeneous samples of polydimethylsiloxane (PDMS) elastomer were used as control substance and were measured to have Poisson ratios of 0.498, 0.503, 0.500, and 0.499, in agreement with the reported Incompressible Value of 0.50. Two carbon nanotube (CNT) elastomer composites of identical composition, but one of a homogeneous and the other of a highly inhomogeneous CNT distribution, were used to determine the spatial resolution with good results. The relaxation of a polydomain liquid crystal elastomer (3D-LCE), a cholesteric liquid crystal elastomer (CLCE), and a polyacrylamide gel (PAAm) in water, were used to determine the temporal resolution of the technique. A video at 25 fps was used to evaluate the time dependence of the 3D-LCE over which time an increase in the Poisson ratio was observed. The 3D-LCE relaxes from its initial state at 0.42 to 0.50, converging towards incompressibility at equilibrium. The CLCE was found to have a similar initial Value of 0.44 but converged to ∼0.60, a consequence of its anisotropic elastic nature. PAAm gel relaxation in water was studied over a time period of 7 hours with digital images taken periodically every minute. Its Poisson ratio was found to decrease smoothly from 0.50 to 0.26, with an accompanying reduction in force. The equilibrium result compares well to the 0.25 Value predicted by a theory of the strain-induced swelling of dilute gels. In summary, we find DIC to be a powerful and easy to implement method of accurately measuring local strains in a range of soft materials.
Dimitri Debruyne - One of the best experts on this subject based on the ideXlab platform.
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precise determination of the poisson ratio in soft materials with 2d digital image correlation
Soft Matter, 2013Co-Authors: Robyn H. Pritchard, Dimitri Debruyne, Pascal Lava, Eugene M. TerentjevAbstract:In this article, we demonstrate the application of digital image correlation (DIC) in evaluating the strains and Poisson ratio of a range of soft materials in terms of their spatial and temporal resolutions. Homogeneous samples of polydimethylsiloxane (PDMS) elastomer were used as control substance and were measured to have Poisson ratios of 0.498, 0.503, 0.500, and 0.499, in agreement with the reported Incompressible Value of 0.50. Two carbon nanotube (CNT) elastomer composites of identical composition, but one of a homogeneous and the other of a highly inhomogeneous CNT distribution, were used to determine the spatial resolution with good results. The relaxation of a polydomain liquid crystal elastomer (3D-LCE), a cholesteric liquid crystal elastomer (CLCE), and a polyacrylamide gel (PAAm) in water, were used to determine the temporal resolution of the technique. A video at 25 fps was used to evaluate the time dependence of the 3D-LCE over which time an increase in the Poisson ratio was observed. The 3D-LCE relaxes from its initial state at 0.42 to 0.50, converging towards incompressibility at equilibrium. The CLCE was found to have a similar initial Value of 0.44 but converged to ∼0.60, a consequence of its anisotropic elastic nature. PAAm gel relaxation in water was studied over a time period of 7 hours with digital images taken periodically every minute. Its Poisson ratio was found to decrease smoothly from 0.50 to 0.26, with an accompanying reduction in force. The equilibrium result compares well to the 0.25 Value predicted by a theory of the strain-induced swelling of dilute gels. In summary, we find DIC to be a powerful and easy to implement method of accurately measuring local strains in a range of soft materials.
Pascal Lava - One of the best experts on this subject based on the ideXlab platform.
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precise determination of the poisson ratio in soft materials with 2d digital image correlation
Soft Matter, 2013Co-Authors: Robyn H. Pritchard, Dimitri Debruyne, Pascal Lava, Eugene M. TerentjevAbstract:In this article, we demonstrate the application of digital image correlation (DIC) in evaluating the strains and Poisson ratio of a range of soft materials in terms of their spatial and temporal resolutions. Homogeneous samples of polydimethylsiloxane (PDMS) elastomer were used as control substance and were measured to have Poisson ratios of 0.498, 0.503, 0.500, and 0.499, in agreement with the reported Incompressible Value of 0.50. Two carbon nanotube (CNT) elastomer composites of identical composition, but one of a homogeneous and the other of a highly inhomogeneous CNT distribution, were used to determine the spatial resolution with good results. The relaxation of a polydomain liquid crystal elastomer (3D-LCE), a cholesteric liquid crystal elastomer (CLCE), and a polyacrylamide gel (PAAm) in water, were used to determine the temporal resolution of the technique. A video at 25 fps was used to evaluate the time dependence of the 3D-LCE over which time an increase in the Poisson ratio was observed. The 3D-LCE relaxes from its initial state at 0.42 to 0.50, converging towards incompressibility at equilibrium. The CLCE was found to have a similar initial Value of 0.44 but converged to ∼0.60, a consequence of its anisotropic elastic nature. PAAm gel relaxation in water was studied over a time period of 7 hours with digital images taken periodically every minute. Its Poisson ratio was found to decrease smoothly from 0.50 to 0.26, with an accompanying reduction in force. The equilibrium result compares well to the 0.25 Value predicted by a theory of the strain-induced swelling of dilute gels. In summary, we find DIC to be a powerful and easy to implement method of accurately measuring local strains in a range of soft materials.
