The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compr...The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.展开更多
[Objective] The paper was to study the adaptability of Australian Merino sheep in the alpine pastoral areas. [Method]Through introduction of Australian Merino sheep for hybridizing with Gansu alpine fine wool sheep,th...[Objective] The paper was to study the adaptability of Australian Merino sheep in the alpine pastoral areas. [Method]Through introduction of Australian Merino sheep for hybridizing with Gansu alpine fine wool sheep,the improvement effect of offspring was observed. [Result]The introduced Australian Merino sheep had good adaptability in the alpine pastoral areas with good hair quality,strong cold resistance and disease resistance,and they could grow and reproduce healthily in the alpine pastoral areas. The application effect of the ram was outstanding,showing large breeding amount,high conception rate and survival rate.[Conclusion]The improvement effect of offspring of Australian Merino sheep and Gansu alpine fine wool sheep was significant,and the growth performance was improved greatly.展开更多
基金Funded by the National Basic Research Program of China(No.2009CB724401)the Major Science and Technology Program of High-end CNC Machine Tools and Basic Manufacturing Equipment(No.2012ZX04003-041)
文摘The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.
基金Supported by Special Fund for Construction of National Wool-purpose Sheep Industry Research System(CARS-40-33)
文摘[Objective] The paper was to study the adaptability of Australian Merino sheep in the alpine pastoral areas. [Method]Through introduction of Australian Merino sheep for hybridizing with Gansu alpine fine wool sheep,the improvement effect of offspring was observed. [Result]The introduced Australian Merino sheep had good adaptability in the alpine pastoral areas with good hair quality,strong cold resistance and disease resistance,and they could grow and reproduce healthily in the alpine pastoral areas. The application effect of the ram was outstanding,showing large breeding amount,high conception rate and survival rate.[Conclusion]The improvement effect of offspring of Australian Merino sheep and Gansu alpine fine wool sheep was significant,and the growth performance was improved greatly.
