Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of N...Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of Newton iteration method was proposed when Newton iteration method was applied to solve the partial differential equations.This scheme could make the X-DIC method suitable for the large deformation measurement and avoid the non-convergence phenomenon effectively.The performance of the X-DIC method was verified by simulated images.Since the pixel point with the maximum absolute error occurred mainly at the corner or on the interface of the region of interest(ROI,region used for correlation calculation),measured deformation of the core area(area surrounding the center point of the ROI with a smaller size) was taken as the reliable measured value.The measurement accuracy of the X-DIC method could be improved greatly by using the core area.Combined with a long-distance microscope,the X-DIC method could be used in the deformation measurement of the micro-region.Zero deformation experiment was done to test the precision of the measurement system.Then,the X-DIC method was applied to measure the micro-region deformation of the specimen with a crack.Test value was proved to be in accordance with the actual deformation,showing that the X-DIC method is suitable for the research of microscale mechanical behavior of materials.展开更多
Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced ceme...Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.展开更多
Uniaxial tensile testing at strain rates ranging from 10-3 to 10-1 s-1 was carried out to study the rate-dependent me-chanical behavior for poly(ethylene terephthalate) (PET) used in the packaging industry. The experi...Uniaxial tensile testing at strain rates ranging from 10-3 to 10-1 s-1 was carried out to study the rate-dependent me-chanical behavior for poly(ethylene terephthalate) (PET) used in the packaging industry. The experimental results show that a rate-dependent plastic behavior exists for PET material. The value of the yield strength was found to increase with the increasing strain rate. A new constitutive model based on the improved Cowper-Symonds rate-dependent constitutive model is proposed to describe the mechanical behavior of PET material in the strain rate ranging from 10-3 to 10-1 s-1, providing more accurate material data for the subsequent simulation analysis of drop test and dynamic buckling. The predictions obtained using the proposed model are compared with experimental results of the improved Cowper-Symonds model. The simulating results of the proposed model agree well with the experimental data. For a low strain rate, the predictions of this model are more precise than those obtained using the improved Cowper-Symonds model. This confirms that the new constitutive model is suitable for describing the me-chanical behavior of PET material at a low strain rate and modeling impact problem.展开更多
The design of high irradiation-resistant materials is very important for the development of next-generation nuclear reactors. Grain boundaries acting as effective defect sinks are thought to be able to moderate the de...The design of high irradiation-resistant materials is very important for the development of next-generation nuclear reactors. Grain boundaries acting as effective defect sinks are thought to be able to moderate the deterioration of mechanical behaviors of irradiated materials, and have drawn increasing attention in recent years. The study of the effect of grain boundaries on the mechanical behaviors of irradiated materials is a multi-scale problem. At the atomic level, grain boundaries can effectively affect the production and formation of irradiation-induced point defects in grain interiors, which leads to the change of density, size distribution and evolution of defect clusters at grain level. The change of microstructure would influence the macroscopic mechanical properties of the irradiated polycrystal. Here we give a brief review about the effect of grain boundaries on the mechanical behaviors of irradiated metals from three scales: microscopic scale, mesoscopic scale and macroscopic scale.展开更多
稳健的铁磁性在稀土和过渡金属共掺杂ZnO纳米颗粒中应用于自旋电子学领域:磁性材料题目:Robust ferromagnetism in rare-earth and transition metal co-doped ZnO nanoparticles for spintronics applications团队:西安交通大学物理学...稳健的铁磁性在稀土和过渡金属共掺杂ZnO纳米颗粒中应用于自旋电子学领域:磁性材料题目:Robust ferromagnetism in rare-earth and transition metal co-doped ZnO nanoparticles for spintronics applications团队:西安交通大学物理学院,凝聚态非平衡合成与调制教育部重点实验室,材料力学行为国家重点实验室,先进功能材料与介观物理重点实验室期刊:Materials Letters(impact factor:3.423)2区进展.展开更多
Yu Qian,a postgraduate of Micro-Nano-Scale Materials Behavior Research Center of the State Key Laboratory of Mechanical Behavior of Metal Materials,Xi'an Jiaotong University,with the cooperation with Prof.Li Ju of...Yu Qian,a postgraduate of Micro-Nano-Scale Materials Behavior Research Center of the State Key Laboratory of Mechanical Behavior of Metal Materials,Xi'an Jiaotong University,with the cooperation with Prof.Li Ju of Pennsylvania University of USA,Dr.Huang Xiaoxu of Raith National Laboratory of Den-展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10772133 and 11072172)the Doctoral Fund of Ministry of Education of China (Grant No. 20090032110006)
文摘Extended digital image correlation(X-DIC) method is one novel test method in experimental mechanics.In this paper,the principle of the X-DIC method was introduced in detail.A selection scheme of the initial value of Newton iteration method was proposed when Newton iteration method was applied to solve the partial differential equations.This scheme could make the X-DIC method suitable for the large deformation measurement and avoid the non-convergence phenomenon effectively.The performance of the X-DIC method was verified by simulated images.Since the pixel point with the maximum absolute error occurred mainly at the corner or on the interface of the region of interest(ROI,region used for correlation calculation),measured deformation of the core area(area surrounding the center point of the ROI with a smaller size) was taken as the reliable measured value.The measurement accuracy of the X-DIC method could be improved greatly by using the core area.Combined with a long-distance microscope,the X-DIC method could be used in the deformation measurement of the micro-region.Zero deformation experiment was done to test the precision of the measurement system.Then,the X-DIC method was applied to measure the micro-region deformation of the specimen with a crack.Test value was proved to be in accordance with the actual deformation,showing that the X-DIC method is suitable for the research of microscale mechanical behavior of materials.
基金supported by the National Natural Science Foundation of China (Grant No. 51278118)the National Basic Research Program of China ("973" Program) (Grant No. 2009CB623200)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.
基金Project (No 2008C11005) supported by the Key Science and Technology Program of Zhejiang Province, China
文摘Uniaxial tensile testing at strain rates ranging from 10-3 to 10-1 s-1 was carried out to study the rate-dependent me-chanical behavior for poly(ethylene terephthalate) (PET) used in the packaging industry. The experimental results show that a rate-dependent plastic behavior exists for PET material. The value of the yield strength was found to increase with the increasing strain rate. A new constitutive model based on the improved Cowper-Symonds rate-dependent constitutive model is proposed to describe the mechanical behavior of PET material in the strain rate ranging from 10-3 to 10-1 s-1, providing more accurate material data for the subsequent simulation analysis of drop test and dynamic buckling. The predictions obtained using the proposed model are compared with experimental results of the improved Cowper-Symonds model. The simulating results of the proposed model agree well with the experimental data. For a low strain rate, the predictions of this model are more precise than those obtained using the improved Cowper-Symonds model. This confirms that the new constitutive model is suitable for describing the me-chanical behavior of PET material at a low strain rate and modeling impact problem.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11225208 and 11521202)
文摘The design of high irradiation-resistant materials is very important for the development of next-generation nuclear reactors. Grain boundaries acting as effective defect sinks are thought to be able to moderate the deterioration of mechanical behaviors of irradiated materials, and have drawn increasing attention in recent years. The study of the effect of grain boundaries on the mechanical behaviors of irradiated materials is a multi-scale problem. At the atomic level, grain boundaries can effectively affect the production and formation of irradiation-induced point defects in grain interiors, which leads to the change of density, size distribution and evolution of defect clusters at grain level. The change of microstructure would influence the macroscopic mechanical properties of the irradiated polycrystal. Here we give a brief review about the effect of grain boundaries on the mechanical behaviors of irradiated metals from three scales: microscopic scale, mesoscopic scale and macroscopic scale.
文摘稳健的铁磁性在稀土和过渡金属共掺杂ZnO纳米颗粒中应用于自旋电子学领域:磁性材料题目:Robust ferromagnetism in rare-earth and transition metal co-doped ZnO nanoparticles for spintronics applications团队:西安交通大学物理学院,凝聚态非平衡合成与调制教育部重点实验室,材料力学行为国家重点实验室,先进功能材料与介观物理重点实验室期刊:Materials Letters(impact factor:3.423)2区进展.
基金financial support from the National Natural Science Fund,"973"projectthe first batch of Innovation & Talents Projects of the State Foreign Experts Bureau/Ministry of Education, respectively
文摘Yu Qian,a postgraduate of Micro-Nano-Scale Materials Behavior Research Center of the State Key Laboratory of Mechanical Behavior of Metal Materials,Xi'an Jiaotong University,with the cooperation with Prof.Li Ju of Pennsylvania University of USA,Dr.Huang Xiaoxu of Raith National Laboratory of Den-
