The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Haixia Zhang - One of the best experts on this subject based on the ideXlab platform.
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STUDY OF THE TRANSVERSAL DEFORMATION OF CORNEAL STRIP UNDER Uniaxial LOADING
Journal of Mechanics in Medicine and Biology, 2018Co-Authors: Haixia Zhang, Di Zhang, Xiao Qin, Hui WangAbstract:Uniaxial Test is easy to access and to obtain accuracy data, but it is difficult to acquire two-dimensional deformation information. We investigated the relationship between the two strain componen...
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STUDY OF THE TRANSVERSAL DEFORMATION OF CORNEAL STRIP UNDER Uniaxial LOADING
Journal of Mechanics in Medicine and Biology, 2018Co-Authors: Haixia Zhang, Di Zhang, Xiao Qin, Hui WangAbstract:Uniaxial Test is easy to access and to obtain accuracy data, but it is difficult to acquire two-dimensional deformation information. We investigated the relationship between the two strain components of corneal strip in Uniaxial Tests, which is the basis for determining of anisotropic strain energy function of cornea via Uniaxial Tests. Nine rabbits were taken. The left and right corneas were cut along superior-inferior (SI) and nasal-temporal (NT) direction, respectively. For each strip the Uniaxial Test was carried out, and the tensile displacements, strip images and loads were recorded. Then the stretching strain, the transversal strains and stress were obtained. Optimization based inverse analysis was utilized to find the best among six fitting models that characterizes the relationship between two strain components in Uniaxial Tests. All models fitted well the experimental data gathered for corneal strips ([Formula: see text]). According to the model selection index, the power model achieved the best performance index: 0.1268 for SI strips and 0.1063 for NT strips versus 0.151 (SI strips) and 0.107 (NT strips) found at most by other models. Thus, it is the most suitable one for describing the relationship between the two strain components of corneal strip during Uniaxial stretching.
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UNDERSTANDING THE VISCOELASTIC PROPERTIES OF RABBIT CORNEA BASED ON STRESS RELAXATION TestS AND CYCLIC Uniaxial TestS
Journal of Mechanics in Medicine and Biology, 2017Co-Authors: Haixia Zhang, Xiuqing Qian, Zhicheng LiuAbstract:Background: Determining the viscoelastic properties of cornea is important in the fields of understanding of the tissue’s response to mechanical actions and the accurate numerical simulation of corneal biomechanical behavior under the effects of keratoconus and refractive surgery. To address this need, we present an approach to model the viscoelastic response of rabbit cornea from Uniaxial Test data. Methods: The corneal strip samples from six rabbits were obtained to perform cyclic Uniaxial tension Tests and stress relaxation Tests. We investigated the suitability of six constitutive models, including empirical models and hyperelastic models, by a quasi-linear viscoelastic law. Applying non-linear optimization techniques, we found material parameters for each different strip sample. Results and conclusions: The model gave a better fit to loading data with [Formula: see text], and predicted the unloading data in the cyclic Uniaxial Tests with errors-of-fit ranging from 0.03 to 0.06. The results indicate that the best model is the power of the first invariant of strain with Prony form relaxation model, and that the method to identify the material parameters are valid for modeling the visoelastic response of cornea from Uniaxial Test data.
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UNDERSTANDING THE VISCOELASTIC PROPERTIES OF RABBIT CORNEA BASED ON STRESS RELAXATION TestS AND CYCLIC Uniaxial TestS
Journal of Mechanics in Medicine and Biology, 2017Co-Authors: Haixia Zhang, Xiuqing Qian, Zhicheng LiuAbstract:Background: Determining the viscoelastic properties of cornea is important in the fields of understanding of the tissue’s response to mechanical actions and the accurate numerical simulation of corneal biomechanical behavior under the effects of keratoconus and refractive surgery. To address this need, we present an approach to model the viscoelastic response of rabbit cornea from Uniaxial Test data. Methods: The corneal strip samples from six rabbits were obtained to perform cyclic Uniaxial tension Tests and stress relaxation Tests. We investigated the suitability of six constitutive models, including empirical models and hyperelastic models, by a quasi-linear viscoelastic law. Applying non-linear optimization techniques, we found material parameters for each different strip sample. Results and conclusions: The model gave a better fit to loading data with R2>0.99, and predicted the unloading data in the cyclic Uniaxial Tests with errors-of-fit ranging from 0.03 to 0.06. The results indicate that the best model is the power of the first invariant of strain with Prony form relaxation model, and that the method to identify the material parameters are valid for modeling the visoelastic response of cornea from Uniaxial Test data.
Piotr Witakowski - One of the best experts on this subject based on the ideXlab platform.
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Strength development dynamic of cement paste: Testing and control
Cement and Concrete Research, 1998Co-Authors: Piotr WitakowskiAbstract:Abstract Compressive strength obtained from Uniaxial Test of concrete samples cured for 28 days under standard conditions is the basis for designing concrete structures. To design and construct concrete structures, one needs to know not only the strength of the material but also the full σ–e function and its development history. The computerized DNW (Dynamika Narastania Wytrzymalości) Testing system was designed specifically to examine material strength development. The system assures objective results and high accuracy of σ–e function regardless of the age of the Test sample. The study also offers examples of σ–e functions and results of strength development research.
Zhicheng Liu - One of the best experts on this subject based on the ideXlab platform.
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UNDERSTANDING THE VISCOELASTIC PROPERTIES OF RABBIT CORNEA BASED ON STRESS RELAXATION TestS AND CYCLIC Uniaxial TestS
Journal of Mechanics in Medicine and Biology, 2017Co-Authors: Haixia Zhang, Xiuqing Qian, Zhicheng LiuAbstract:Background: Determining the viscoelastic properties of cornea is important in the fields of understanding of the tissue’s response to mechanical actions and the accurate numerical simulation of corneal biomechanical behavior under the effects of keratoconus and refractive surgery. To address this need, we present an approach to model the viscoelastic response of rabbit cornea from Uniaxial Test data. Methods: The corneal strip samples from six rabbits were obtained to perform cyclic Uniaxial tension Tests and stress relaxation Tests. We investigated the suitability of six constitutive models, including empirical models and hyperelastic models, by a quasi-linear viscoelastic law. Applying non-linear optimization techniques, we found material parameters for each different strip sample. Results and conclusions: The model gave a better fit to loading data with [Formula: see text], and predicted the unloading data in the cyclic Uniaxial Tests with errors-of-fit ranging from 0.03 to 0.06. The results indicate that the best model is the power of the first invariant of strain with Prony form relaxation model, and that the method to identify the material parameters are valid for modeling the visoelastic response of cornea from Uniaxial Test data.
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UNDERSTANDING THE VISCOELASTIC PROPERTIES OF RABBIT CORNEA BASED ON STRESS RELAXATION TestS AND CYCLIC Uniaxial TestS
Journal of Mechanics in Medicine and Biology, 2017Co-Authors: Haixia Zhang, Xiuqing Qian, Zhicheng LiuAbstract:Background: Determining the viscoelastic properties of cornea is important in the fields of understanding of the tissue’s response to mechanical actions and the accurate numerical simulation of corneal biomechanical behavior under the effects of keratoconus and refractive surgery. To address this need, we present an approach to model the viscoelastic response of rabbit cornea from Uniaxial Test data. Methods: The corneal strip samples from six rabbits were obtained to perform cyclic Uniaxial tension Tests and stress relaxation Tests. We investigated the suitability of six constitutive models, including empirical models and hyperelastic models, by a quasi-linear viscoelastic law. Applying non-linear optimization techniques, we found material parameters for each different strip sample. Results and conclusions: The model gave a better fit to loading data with R2>0.99, and predicted the unloading data in the cyclic Uniaxial Tests with errors-of-fit ranging from 0.03 to 0.06. The results indicate that the best model is the power of the first invariant of strain with Prony form relaxation model, and that the method to identify the material parameters are valid for modeling the visoelastic response of cornea from Uniaxial Test data.
Nagahisa Ogasawara - One of the best experts on this subject based on the ideXlab platform.
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Critical strain of the sharp indentation through serration behavior with strain rate
International Journal of Mechanical Sciences, 2019Co-Authors: Tsuyoshi Kami, Hiroyuki Yamada, Nagahisa OgasawaraAbstract:Abstract The indentation Test is often used to determine the mechanical properties of materials, and its results are typically compared with Uniaxial Test results. However, the relationship between the indentation and Uniaxial Tests is unclear. Previously, the limit at which the indentation and Uniaxial Tests can be related has been determined by finite element simulation and termed the critical strain of indentation. In the critical strain concept, the high strain of the stress–strain curve has a negligible effect on the indentation load–displacement curve. To date, the effect of critical strain has not been addressed in indentation experiments. In this study, the serration behavior of an Al-Zn-Mg alloy during natural aging was investigated using Uniaxial tensile and indentation Tests in order to clarify (i) the relationship between these Tests and (ii) the critical strain of indentation. Similar to Uniaxial Tests, the serration behavior of indentation was affected by the strain rate effect. However, it was found that the serration behavior observed at high strain in the Uniaxial Test could not be observed in the indentation Test, as indicated by the concept of critical strain. With aging, the serrations of the indentation disappeared; however, they were observed in the Uniaxial Tests. It was confirmed that the migration of Mg atoms affected the serration behavior of indentation. The critical strain was experimentally found by comparing Uniaxial Test and indentation Test results.
S. Thiruvarudchelvan - One of the best experts on this subject based on the ideXlab platform.
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Cavitation phenomenon of commercially pure titanium
Journal of Materials Processing Technology, 2007Co-Authors: M. J. Tan, X. J. Zhu, S. ThiruvarudchelvanAbstract:Abstract Cavitation caused during superplastic straining of a commercially pure titanium alloy under Uniaxial Test was studied. Tensile Tests were conducted with a constant strain rate of 0.01 s −1 at different temperatures. Studies show that commercially pure titanium alloy does not show good superplasticity due to cavitation. Many cavitations are formed at the grain boundary of triple points during tensile Test at relatively low temperatures (below 600 °C). As strain increase, both the number of cavities and the average cavity diameter increase. However, no such phenomena can be found when the alloy deformed at higher temperatures (750 and 800 °C). Studies also show that the pre-existing defects are the main cause for cavitation formation. These defects can be sintered when deformed at temperature above 750 °C.
