In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA f...In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA fibers along with other local ingredients,such as fly ash,cement and sand.In addition to the economic analysis of ECC,the four-point bending test and the optical microscope are employed to investigate the deflection capacity of ECC,its crack width and the occurrence of the self-healing phenomenon.The experimental results suggest that ECC made with domestic ingredients exhibits larger deformability and the average crack width is controlled around 60 μm.Furthermore,the self-healing behavior is observed in cracks of the specimens after cycles of wet and dry curing.The economic analysis shows that the cost of ECC can be greatly reduced via employing domestic PVA fibers.It is,therefore,feasible to produce low cost ECC material employing domestic PVA fibers,while simultaneously retaining high material ductility.展开更多
In order to investigate the effect of microvoids on the mechanical behavior of casting magnesium alloy,a spherical void-cell model of the material was presented.The velocity and strain fields of the model were obtaine...In order to investigate the effect of microvoids on the mechanical behavior of casting magnesium alloy,a spherical void-cell model of the material was presented.The velocity and strain fields of the model were obtained from the assumption that the material matrix is homogeneous and incompressible.The hardening and softening functions,which respectively reflect the deformation-hardening and void-softening behaviors of the material,were presented and introduced to an endochronic constitutive equation for describing the mechanical behavior of the material including microvoids.The corresponding numerical algorithm and finite element procedure were developed and applied to the analyses of the elastoplastic response and the porosity of casting magnesium alloy ZL102.The computed results show satisfactory agreement with experimental data.展开更多
The geometric shapes of specimens are important in impact tensile tests because geometric shapes determine the stress states of the specimens, and precise geometric shapes can obtain proper material properties without...The geometric shapes of specimens are important in impact tensile tests because geometric shapes determine the stress states of the specimens, and precise geometric shapes can obtain proper material properties without non-material factors. The aim of this study was to investigate the 1D form of the stress by changing the length-to-diameter (L/D) ratios of specimens. The experiments were carried out on a split Hopkinson tensile bar (SHTB)-rotating disk indirect bar-bar tensile impact apparatus. The L/D ratios of the LY12CZ specimens used in the test ranged from 1 to 5. Results show that the specimens can be used to obtain exact parameters of materials under the proposed conditions when the L/D ratio is greater than 2. This is because the longer length will reduce or eliminate the effects of the interfaces.展开更多
Room-temperature sodium-ion batteries have attracted increasing interest in recent years because of abundant sodium reserves and the low costs.Grid-scale energy storage applications are particularly relevant to this b...Room-temperature sodium-ion batteries have attracted increasing interest in recent years because of abundant sodium reserves and the low costs.Grid-scale energy storage applications are particularly relevant to this battery technology.Here,we present our recent progress in researching room-temperature sodium-ion batteries,and focus on new electrode materials,including cathodes and anodes,for both non-aqueous and aqueous systems.展开更多
基金The National Natural Science Foundation of China (No.51008071,51278097)the Natural Science Foundation of Jiangsu Province(No.BK2010413)+2 种基金Teaching & Research Excellence Grant for Young Faculty Member at Southeast Universitythe Program for Special Talents in Six Major Fields of Jiangsu Province(No.2011-JZ-011)the Scientific Research Innovation Project for College Graduates in Jiangsu Province(No.CXLX_0136)
文摘In order to reduce the cost of high performance polyvinyl alcohol（PVA） fiber reinforced cementitious material（called engineered cementitious composites,ECC）,a ductile ECC material is developed using domestic PVA fibers along with other local ingredients,such as fly ash,cement and sand.In addition to the economic analysis of ECC,the four-point bending test and the optical microscope are employed to investigate the deflection capacity of ECC,its crack width and the occurrence of the self-healing phenomenon.The experimental results suggest that ECC made with domestic ingredients exhibits larger deformability and the average crack width is controlled around 60 μm.Furthermore,the self-healing behavior is observed in cracks of the specimens after cycles of wet and dry curing.The economic analysis shows that the cost of ECC can be greatly reduced via employing domestic PVA fibers.It is,therefore,feasible to produce low cost ECC material employing domestic PVA fibers,while simultaneously retaining high material ductility.
基金Project(10872221)supported by the National Natural Science Foundation of China
文摘In order to investigate the effect of microvoids on the mechanical behavior of casting magnesium alloy,a spherical void-cell model of the material was presented.The velocity and strain fields of the model were obtained from the assumption that the material matrix is homogeneous and incompressible.The hardening and softening functions,which respectively reflect the deformation-hardening and void-softening behaviors of the material,were presented and introduced to an endochronic constitutive equation for describing the mechanical behavior of the material including microvoids.The corresponding numerical algorithm and finite element procedure were developed and applied to the analyses of the elastoplastic response and the porosity of casting magnesium alloy ZL102.The computed results show satisfactory agreement with experimental data.
文摘The geometric shapes of specimens are important in impact tensile tests because geometric shapes determine the stress states of the specimens, and precise geometric shapes can obtain proper material properties without non-material factors. The aim of this study was to investigate the 1D form of the stress by changing the length-to-diameter (L/D) ratios of specimens. The experiments were carried out on a split Hopkinson tensile bar (SHTB)-rotating disk indirect bar-bar tensile impact apparatus. The L/D ratios of the LY12CZ specimens used in the test ranged from 1 to 5. Results show that the specimens can be used to obtain exact parameters of materials under the proposed conditions when the L/D ratio is greater than 2. This is because the longer length will reduce or eliminate the effects of the interfaces.
基金supported by funding from the National Natural Science Foundation of China(51222210,50972164,11234013,11005161,11205249)One Hundred Talent Project of the Chinese Academy of Sciences
文摘Room-temperature sodium-ion batteries have attracted increasing interest in recent years because of abundant sodium reserves and the low costs.Grid-scale energy storage applications are particularly relevant to this battery technology.Here,we present our recent progress in researching room-temperature sodium-ion batteries,and focus on new electrode materials,including cathodes and anodes,for both non-aqueous and aqueous systems.
