The analysis of plane strain elastic-plastic bending of a linear strain hardening curved beam with a narrow rectangular cross section subjected to couples at its end is conducted based on a unified yield criterion. Th...The analysis of plane strain elastic-plastic bending of a linear strain hardening curved beam with a narrow rectangular cross section subjected to couples at its end is conducted based on a unified yield criterion. The solutions for the mechanical properties of plane strain bending are derived, which are adapted for various kinds of non-strength differential materials and can be degenerated to those based on the Tresca, von Mises, and twin-shear yield criteria. The dependences of the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane on different yield criteria and Poisson’s ratios are discussed. The results show that the influences of different yield criteria and Poisson’s ratio on the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane of the curved beam are significant. Once the value of bis obtained by experiments, the yield criterion and the corresponding solution for the materials of interest are then determined.展开更多
The B4C/2024Al composites were successfully produced by pressureless infiltration method, and the effects of heat treatment on phase content and mechanical properties were investigated by X-ray diffraction （XRD）, sc...The B4C/2024Al composites were successfully produced by pressureless infiltration method, and the effects of heat treatment on phase content and mechanical properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and mechanical properties testing. The results show that phases of BnC/2024Al composites include B4C, Al, Al3BC, AlB2 and Al2Cu. The phase species remain unchanged; however, the phase content of the composites changes significantly after heat treatment at the temperature of 660, 700, 800 or 900 ℃ for 12, 24 or 36 h. It is found that the heat treatment results in not only considerable enhancement in hardness, but also reduction in bending strength of the composites. Heat treatment at 800 ℃ for 36 h does best to hardness of the composites, while at 700 ℃ for 36 h it is the most beneficial to their comprehensive mechanical properties.展开更多
Tungsten heavy alloys(90W-6Ni-4Mn)were prepared through spark plasma sintering(SPS)using micron-sized W,Ni,and Mn powders without ball milling as raw materials.The effects of sintering temperature on the microstructur...Tungsten heavy alloys(90W-6Ni-4Mn)were prepared through spark plasma sintering(SPS)using micron-sized W,Ni,and Mn powders without ball milling as raw materials.The effects of sintering temperature on the microstructure and mechanicalproperties of the90W-6Ni-4Mn alloys were investigated.SPS technology was used to prepare90W-6Ni-4Mn alloys withrelatively high density and excellent comprehensive performance at1150-1250°C for3min.The90W-6Ni-4Mn alloys consistedof the W phase and theγ-(Ni,Mn,and W)binding phase,and the average grain size was less than10μm.The Rockwell hardness andbending strength of alloys first increased and then decreased with increasing sintering temperature.The best comprehensiveperformance was obtained at1200°C,its hardness and bending strength were HRA68.7and1162.72MPa,respectively.展开更多
Gene of animal keratin can be inoculated into cotton fiber and thus get the keratin transgenic cotton fiber through transgenic technology. Handle of two kinds of pure cotton poplin, one of which is made of the keratin...Gene of animal keratin can be inoculated into cotton fiber and thus get the keratin transgenic cotton fiber through transgenic technology. Handle of two kinds of pure cotton poplin, one of which is made of the keratin transgenic cotton while the other is made of the ordinary cotton of the same breed as control group and both with absolutely identical spinning, weaving, and dyeing process, was objectively evaluated with KES system. The result of analysis indicates that the principal changes of keratin transgenic cotton fabric are that the bending and shearing property of the fabric are considerably enhanced, KOSHI (Stiffness) and HARI (Anti-drape stiffness) of the fabric are good, while SHINAYAKASA (Flexibility with soft feeling) and SHARI (Crispness) decline.展开更多
The mechanical characteristics of the weld joint were investigated by tensile test, microstructure test, and microhardness test. The welded tube NC bending tests were carried out to evaluate the weld on the formabilit...The mechanical characteristics of the weld joint were investigated by tensile test, microstructure test, and microhardness test. The welded tube NC bending tests were carried out to evaluate the weld on the formability of the QSTE340 welded tube. The results show that the wall thinning degree, cross-sectional deformation and springback angle increase significantly as the weld line is located on the outside of the bend compared with that located on the middle and inside, and the welded tubes produce nearly identical performance as the weld line is located on the middle and inside. The wall thickening degree decreases much as the weld line is located on the inside of the bend. So the welded tube can acquire good bending formability as the weld line is located in the region away from the outside of the bend.展开更多
基金The Project of the Ministry of Housing and Urban-Rural Development(No.2014-K4-010)
文摘The analysis of plane strain elastic-plastic bending of a linear strain hardening curved beam with a narrow rectangular cross section subjected to couples at its end is conducted based on a unified yield criterion. The solutions for the mechanical properties of plane strain bending are derived, which are adapted for various kinds of non-strength differential materials and can be degenerated to those based on the Tresca, von Mises, and twin-shear yield criteria. The dependences of the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane on different yield criteria and Poisson’s ratios are discussed. The results show that the influences of different yield criteria and Poisson’s ratio on the two critical bending moments, the radii of the interfaces between the elastic and plastic regions and the radial displacements of the points at the symmetrical plane of the curved beam are significant. Once the value of bis obtained by experiments, the yield criterion and the corresponding solution for the materials of interest are then determined.
基金Project(2011CB605805)supported by the National Basic Research Program of China
文摘The B4C/2024Al composites were successfully produced by pressureless infiltration method, and the effects of heat treatment on phase content and mechanical properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and mechanical properties testing. The results show that phases of BnC/2024Al composites include B4C, Al, Al3BC, AlB2 and Al2Cu. The phase species remain unchanged; however, the phase content of the composites changes significantly after heat treatment at the temperature of 660, 700, 800 or 900 ℃ for 12, 24 or 36 h. It is found that the heat treatment results in not only considerable enhancement in hardness, but also reduction in bending strength of the composites. Heat treatment at 800 ℃ for 36 h does best to hardness of the composites, while at 700 ℃ for 36 h it is the most beneficial to their comprehensive mechanical properties.
基金Projects(51464010,51461014)supported by the National Natural Science Foundation of ChinaProject(20165207)supported by the Natural Science Foundation of Hainan Province,China
文摘Tungsten heavy alloys(90W-6Ni-4Mn)were prepared through spark plasma sintering(SPS)using micron-sized W,Ni,and Mn powders without ball milling as raw materials.The effects of sintering temperature on the microstructure and mechanicalproperties of the90W-6Ni-4Mn alloys were investigated.SPS technology was used to prepare90W-6Ni-4Mn alloys withrelatively high density and excellent comprehensive performance at1150-1250°C for3min.The90W-6Ni-4Mn alloys consistedof the W phase and theγ-(Ni,Mn,and W)binding phase,and the average grain size was less than10μm.The Rockwell hardness andbending strength of alloys first increased and then decreased with increasing sintering temperature.The best comprehensiveperformance was obtained at1200°C,its hardness and bending strength were HRA68.7and1162.72MPa,respectively.
文摘Gene of animal keratin can be inoculated into cotton fiber and thus get the keratin transgenic cotton fiber through transgenic technology. Handle of two kinds of pure cotton poplin, one of which is made of the keratin transgenic cotton while the other is made of the ordinary cotton of the same breed as control group and both with absolutely identical spinning, weaving, and dyeing process, was objectively evaluated with KES system. The result of analysis indicates that the principal changes of keratin transgenic cotton fabric are that the bending and shearing property of the fabric are considerably enhanced, KOSHI (Stiffness) and HARI (Anti-drape stiffness) of the fabric are good, while SHINAYAKASA (Flexibility with soft feeling) and SHARI (Crispness) decline.
基金Supported by National Natural Science Foundation of China (No. 50875216)
文摘The mechanical characteristics of the weld joint were investigated by tensile test, microstructure test, and microhardness test. The welded tube NC bending tests were carried out to evaluate the weld on the formability of the QSTE340 welded tube. The results show that the wall thinning degree, cross-sectional deformation and springback angle increase significantly as the weld line is located on the outside of the bend compared with that located on the middle and inside, and the welded tubes produce nearly identical performance as the weld line is located on the middle and inside. The wall thickening degree decreases much as the weld line is located on the inside of the bend. So the welded tube can acquire good bending formability as the weld line is located in the region away from the outside of the bend.
