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Jitladda Sakdapipanich - One of the best experts on this subject based on the ideXlab platform.
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entanglements and networks to strain induced crystallization and stress strain Relations in natural rubber and synthetic polyisoprene at various temperatures
Macromolecules, 2013Co-Authors: Shigeyuki Toki, Justin Che, Lixia Rong, Benjamin S Hsiao, Sureerut Amnuaypornsri, Adul Nimpaiboon, Jitladda SakdapipanichAbstract:Stress–strain Relations and strain-induced crystallization (SIC) of unvulcanized and vulcanized states of natural rubber (NR) and synthetic polyisoprene (IR) were studied using synchrotron X-ray at various temperatures from −50 to +75 °C. Unvulcanized IR is a polymer melt that shows a viscous response with yield stress that is related to entanglement and no SIC at 25 °C. However, unvulcanized IR shows SIC at 0, −25, and −50 °C. Entanglements in unvulcanized IR become pivots to align chains and induce crystals at low temperatures. On the other hand, unvulcanized NR shows SIC and stress upturns in stress–strain Relations at 25 °C. Since a permanent set is observed after large extension and retraction, unvulcanized NR has a pseudo end-linked network. The pseudo end-linked networks make entanglements as permanent entanglements and show stress upturn and SIC. Vulcanization makes IR to a rubber which shows a stress upturn and SIC by chemical bond network. The stress of vulcanized NR and IR appear almost the sam...
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Entanglements and Networks to Strain-Induced Crystallization and Stress–Strain Relations in Natural Rubber and Synthetic Polyisoprene at Various Temperatures
Macromolecules, 2013Co-Authors: Shigeyuki Toki, Justin Che, Lixia Rong, Benjamin S Hsiao, Sureerut Amnuaypornsri, Adul Nimpaiboon, Jitladda SakdapipanichAbstract:Stress–strain Relations and strain-induced crystallization (SIC) of unvulcanized and vulcanized states of natural rubber (NR) and synthetic polyisoprene (IR) were studied using synchrotron X-ray at various temperatures from −50 to +75 °C. Unvulcanized IR is a polymer melt that shows a viscous response with yield stress that is related to entanglement and no SIC at 25 °C. However, unvulcanized IR shows SIC at 0, −25, and −50 °C. Entanglements in unvulcanized IR become pivots to align chains and induce crystals at low temperatures. On the other hand, unvulcanized NR shows SIC and stress upturns in stress–strain Relations at 25 °C. Since a permanent set is observed after large extension and retraction, unvulcanized NR has a pseudo end-linked network. The pseudo end-linked networks make entanglements as permanent entanglements and show stress upturn and SIC. Vulcanization makes IR to a rubber which shows a stress upturn and SIC by chemical bond network. The stress of vulcanized NR and IR appear almost the sam...
Yunqiang Peng - One of the best experts on this subject based on the ideXlab platform.
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A Theoretical Model for Predicting Uniaxial Stress–Strain Relations of Ductile Materials by Small Disk Experiments Based on Equivalent Energy Method
Transactions of the Indian Institute of Metals, 2018Co-Authors: Yunqiang Peng, Lixun Cai, Chen Hui, Bao ChenAbstract:In this study, a constitutive relation parameters (CRP) model for mini-Brazilian disk (MBD) experiment and small punch testing (SPT) experiment have been put forward according to equivalent energy method, which can be expediently used to determine the uniaxial stress–strain Relationships of ductile materials by small disks. Moreover, the ultimate tensile stress of ductile materials can be determined via a classical derivation. In order to verify the CRP model, lots of finite element analyses were carried out by ANSYS 14.5 based on the imaginary power-law stress–strain Relations generating different elasticity modulus, yield stress and strain hardening exponent, and the results indicate that the stress–strain Relations determined from MBD and SPT experiments by CRP model are in excellent agreement with the Relations with inputs from FEA. Further, two kinds of experiments on P92 and DP600 were conducted, respectively, and the stress–strain Relationships and the corresponding ultimate stress determined by CRP model were in accord with the standard tension results.
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a new method based on energy principle to predict uniaxial stress strain Relations of ductile materials by small punch testing
International Journal of Mechanical Sciences, 2018Co-Authors: Yunqiang Peng, Lixun Cai, Hui Chen, Chen BaoAbstract:Abstract Uniaxial stress–strain Relations of ductile materials are the most fundamental requirement for the design and safety assessment of structures. In this paper, a novel small punch testing (SPT)-related stress–strain relation (SPT-SR) model is proposed to predict the stress–strain Relations of materials on the basis of equivalent energy principle. To examine the validity of the model, numerical simulations by finite element analysis (FEA) with a series of hypothetical materials with different Hollomon's material parameters were carried out. The results demonstrate that the uniaxial stress–strain Relations predicted by SPT-SR model from simulated load-displacement curves are in good agreement with the properties of hypothetical materials used in FEA. Furthermore, SPT experiments and tensile tests for four steels (P92, DP600, Q345B, A508-III) at room temperature and 300 °C were conducted. The stress–strain Relations predicted by SPT-SR model agree well with the tensile results generated from finite-element-analysis aided testing (FAT) method. Compared with the tensile strengths obtained by uniaxial tensile tests, they can also be well determined based on the strength coefficient and strain hardening exponent predicted by SPT-SR model.
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A new method based on energy principle to predict uniaxial stress–strain Relations of ductile materials by small punch testing
International Journal of Mechanical Sciences, 2018Co-Authors: Yunqiang Peng, Lixun Cai, Hui Chen, Bao ChenAbstract:Abstract Uniaxial stress–strain Relations of ductile materials are the most fundamental requirement for the design and safety assessment of structures. In this paper, a novel small punch testing (SPT)-related stress–strain relation (SPT-SR) model is proposed to predict the stress–strain Relations of materials on the basis of equivalent energy principle. To examine the validity of the model, numerical simulations by finite element analysis (FEA) with a series of hypothetical materials with different Hollomon's material parameters were carried out. The results demonstrate that the uniaxial stress–strain Relations predicted by SPT-SR model from simulated load-displacement curves are in good agreement with the properties of hypothetical materials used in FEA. Furthermore, SPT experiments and tensile tests for four steels (P92, DP600, Q345B, A508-III) at room temperature and 300 °C were conducted. The stress–strain Relations predicted by SPT-SR model agree well with the tensile results generated from finite-element-analysis aided testing (FAT) method. Compared with the tensile strengths obtained by uniaxial tensile tests, they can also be well determined based on the strength coefficient and strain hardening exponent predicted by SPT-SR model.
William D. Nix - One of the best experts on this subject based on the ideXlab platform.
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A microbeam bending method for studying stress–strain Relations for metal thin films on silicon substrates
Journal of the Mechanics and Physics of Solids, 2005Co-Authors: J.n. Florando, William D. NixAbstract:Abstract We have developed a microbeam bending technique for determining elastic–plastic, stress–strain Relations for thin metal films on silicon substrates. The method is similar to previous microbeam bending techniques, except that triangular silicon microbeams are used in place of rectangular beams. The triangular beam has the advantage that the entire film on the top surface of the beam is subjected to a uniform state of plane strain as the beam is deflected, unlike the standard rectangular geometry where the bending is concentrated at the support. To extract the average stress–strain Relations for the film, we present a method of analysis that requires computation of the neutral plane for bending, which changes as the film deforms plastically. This method can be used to determine the elastic–plastic properties of thin metal films on silicon substrates up to strains of about 1%. Utilizing this technique, both yielding and strain hardening of Cu thin films on silicon substrates have been investigated. Copper films with dual crystallographic textures and different grain sizes, as well as others with strong 〈1 1 1〉 textures have been studied. Three strongly textured 〈1 1 1〉 films were studied to examine the effect of film thickness on the deformation properties of the film. These films show very high rates of work hardening, and an increase in the yield stress and work hardening rate with decreasing film thickness, consistent with current dislocation models.
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A Microbeam Bending Method for Studying Stress-Strain Relations for Metal Thin Films on Silicon Substrates
2004Co-Authors: J.n. Florando, William D. NixAbstract:We have developed a microbeam bending technique for determining elastic-plastic, Stress-Strain Relations for thin metal films on silicon substrates. The method is similar to previous microbeam bending techniques, except that triangular silicon microbeams are used in place of rectangular beams. The triangular beam has the advantage that the entire film on the top surface of the beam is subjected to a uniform state of plane strain as the beam is deflected, unlike the standard rectangular geometry where the bending is concentrated at the support. We present a method of analysis for determining two Ramberg-Osgood parameters for describing the Stress-Strain relation for the film. These parameters are obtained by fitting the elastic-plastic model to the measured load-displacement data, and utilizing the known elastic properties of both film and substrate. As a part of the analysis we compute the position of the neutral plane for bending, which changes as the film deforms plastically. This knowledge, in turn, allows average Stress-Strain Relations to be determined accurately without forcing the film to closely follow the Ramberg-Osgood law. The method we have developed can be used to determine the elastic-plastic properties of thin metal films on silicon substrates up to strains of about 1%. Utilizingmore » this technique, both yielding and strain hardening of Cu thin films on silicon substrates have been investigated. Copper films with dual crystallographic textures and different grain sizes, as well as others with strong textures have been studied. Three strongly textured films were studied to examine the effect of film thickness on the deformation properties of the film. These films show very high rates of work hardening, and an increase in the yield stress and work hardening rate with decreasing film thickness, consistent with current dislocation models.« less
Bao Chen - One of the best experts on this subject based on the ideXlab platform.
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Novel Ring Compression Test Method to Determine the Stress-Strain Relations and Mechanical Preperties of Metallic Materials
2021Co-Authors: Guang-zhao Han, Bao Chen, Cai Lixun, Bo Liang, Mao-bo Huang, Liu XiaokunAbstract:Abstract Although there are methods for testing the stress–strain relation and strength, which are the most fundamental and important properties of metallic materials, their application to small size specimens is limited. In this study, a new dimensionless elastoplastic load–displacement (EPLD-Ring) model for compressed metal rings with isotropy and constitutive power law is proposed to describe the relation between the geometric dimensions, Hollomon law parameters, load, and displacement based on energy density equivalence. Furthermore, a novel test method for the rings is developed to obtain the elastic modulus, stress–strain relation, yield strength, and tensile strength. The universality and accuracy of the model are verified within a wide range of imaginary materials via finite element analysis (FEA), and the results show that the stress–strain Relations obtained with the model are more consistent with those inputted in the FEA software. Additionally, for seven metallic materials, a series of ring compression tests with various dimensions were performed. It was found that the stress–strain Relations and mechanical properties predicted by the model are in agreement with the normal tensile test results. It is believed that the new method is reliable and effective for testing the mechanical properties of small size materials and tube components.
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A Theoretical Model for Predicting Uniaxial Stress–Strain Relations of Ductile Materials by Small Disk Experiments Based on Equivalent Energy Method
Transactions of the Indian Institute of Metals, 2018Co-Authors: Yunqiang Peng, Lixun Cai, Chen Hui, Bao ChenAbstract:In this study, a constitutive relation parameters (CRP) model for mini-Brazilian disk (MBD) experiment and small punch testing (SPT) experiment have been put forward according to equivalent energy method, which can be expediently used to determine the uniaxial stress–strain Relationships of ductile materials by small disks. Moreover, the ultimate tensile stress of ductile materials can be determined via a classical derivation. In order to verify the CRP model, lots of finite element analyses were carried out by ANSYS 14.5 based on the imaginary power-law stress–strain Relations generating different elasticity modulus, yield stress and strain hardening exponent, and the results indicate that the stress–strain Relations determined from MBD and SPT experiments by CRP model are in excellent agreement with the Relations with inputs from FEA. Further, two kinds of experiments on P92 and DP600 were conducted, respectively, and the stress–strain Relationships and the corresponding ultimate stress determined by CRP model were in accord with the standard tension results.
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A new method based on energy principle to predict uniaxial stress–strain Relations of ductile materials by small punch testing
International Journal of Mechanical Sciences, 2018Co-Authors: Yunqiang Peng, Lixun Cai, Hui Chen, Bao ChenAbstract:Abstract Uniaxial stress–strain Relations of ductile materials are the most fundamental requirement for the design and safety assessment of structures. In this paper, a novel small punch testing (SPT)-related stress–strain relation (SPT-SR) model is proposed to predict the stress–strain Relations of materials on the basis of equivalent energy principle. To examine the validity of the model, numerical simulations by finite element analysis (FEA) with a series of hypothetical materials with different Hollomon's material parameters were carried out. The results demonstrate that the uniaxial stress–strain Relations predicted by SPT-SR model from simulated load-displacement curves are in good agreement with the properties of hypothetical materials used in FEA. Furthermore, SPT experiments and tensile tests for four steels (P92, DP600, Q345B, A508-III) at room temperature and 300 °C were conducted. The stress–strain Relations predicted by SPT-SR model agree well with the tensile results generated from finite-element-analysis aided testing (FAT) method. Compared with the tensile strengths obtained by uniaxial tensile tests, they can also be well determined based on the strength coefficient and strain hardening exponent predicted by SPT-SR model.
Shigeyuki Toki - One of the best experts on this subject based on the ideXlab platform.
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entanglements and networks to strain induced crystallization and stress strain Relations in natural rubber and synthetic polyisoprene at various temperatures
Macromolecules, 2013Co-Authors: Shigeyuki Toki, Justin Che, Lixia Rong, Benjamin S Hsiao, Sureerut Amnuaypornsri, Adul Nimpaiboon, Jitladda SakdapipanichAbstract:Stress–strain Relations and strain-induced crystallization (SIC) of unvulcanized and vulcanized states of natural rubber (NR) and synthetic polyisoprene (IR) were studied using synchrotron X-ray at various temperatures from −50 to +75 °C. Unvulcanized IR is a polymer melt that shows a viscous response with yield stress that is related to entanglement and no SIC at 25 °C. However, unvulcanized IR shows SIC at 0, −25, and −50 °C. Entanglements in unvulcanized IR become pivots to align chains and induce crystals at low temperatures. On the other hand, unvulcanized NR shows SIC and stress upturns in stress–strain Relations at 25 °C. Since a permanent set is observed after large extension and retraction, unvulcanized NR has a pseudo end-linked network. The pseudo end-linked networks make entanglements as permanent entanglements and show stress upturn and SIC. Vulcanization makes IR to a rubber which shows a stress upturn and SIC by chemical bond network. The stress of vulcanized NR and IR appear almost the sam...
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Entanglements and Networks to Strain-Induced Crystallization and Stress–Strain Relations in Natural Rubber and Synthetic Polyisoprene at Various Temperatures
Macromolecules, 2013Co-Authors: Shigeyuki Toki, Justin Che, Lixia Rong, Benjamin S Hsiao, Sureerut Amnuaypornsri, Adul Nimpaiboon, Jitladda SakdapipanichAbstract:Stress–strain Relations and strain-induced crystallization (SIC) of unvulcanized and vulcanized states of natural rubber (NR) and synthetic polyisoprene (IR) were studied using synchrotron X-ray at various temperatures from −50 to +75 °C. Unvulcanized IR is a polymer melt that shows a viscous response with yield stress that is related to entanglement and no SIC at 25 °C. However, unvulcanized IR shows SIC at 0, −25, and −50 °C. Entanglements in unvulcanized IR become pivots to align chains and induce crystals at low temperatures. On the other hand, unvulcanized NR shows SIC and stress upturns in stress–strain Relations at 25 °C. Since a permanent set is observed after large extension and retraction, unvulcanized NR has a pseudo end-linked network. The pseudo end-linked networks make entanglements as permanent entanglements and show stress upturn and SIC. Vulcanization makes IR to a rubber which shows a stress upturn and SIC by chemical bond network. The stress of vulcanized NR and IR appear almost the sam...
