Volumetric defects in high-strength aluminum alloy components were repaired via friction stir remanufacturing(FSR).Various consumable pins made of AA7075-T6 were designed.Top diameters of the consumable pins afected m...Volumetric defects in high-strength aluminum alloy components were repaired via friction stir remanufacturing(FSR).Various consumable pins made of AA7075-T6 were designed.Top diameters of the consumable pins afected material fow,which ensured that the materials at the repairing interface were forged to metallurgical bonding.Conical angles determined load transfer besides material fow,which afected the fracture of the pins before the dwelling stage.Sound repaired components were achieved when the conical angle of the consumable pin was 1°larger than that of the volumetric defect.The ultimate tensile strength and elongation of the repaired components reached 445.9 MPa and 9.6%,respectively.The design criteria of the consumable pin in the FSR was established,which provided valuable references to repair volumetric defects in high-strength aluminum components.展开更多
Hydrogen bonding is considered to have significant effect on the interaction between polymeric chains and on the viscoelasticity of the polymeric materials. In this paper, we attempt to discuss the relationship betwee...Hydrogen bonding is considered to have significant effect on the interaction between polymeric chains and on the viscoelasticity of the polymeric materials. In this paper, we attempt to discuss the relationship between hydrogen bonding density and damping behavior and mechanical properties of polyethylene-based polymeric materials. For this reason, a series of pendant chain hydrogen bonding polymers （PCHBP） with different hydrogen bonding density （HBD） were prepared by quantitatively changing the content of pendent hydroxyl groups on the main chain of polyethylene. It was found that PCItBP with low HBD showed similar properties to polyethylene, indicating that the property of the materials was dependent mainly on the structure of the main chain. However, PCHBP with high HBD exhibited two tandpeaks and a platform of loss modulus as well as a high storage modulus （about 400 MPa） at the second tand peak temperature, demonstrating that a polymeric material with high strength and damping properties was obtained. More importantly, the maximum of loss modulus showed a linear increase with the HBD, indicating that a higher HBD greatly improved the damping properties of the polymeric materials.展开更多
交错网格物质点法(Staggered Grid Material Point Method,SGMP)有效地消除了物质点法(Material Point Method,MPM)的跨网格数值误差,是模拟冲击爆炸等涉及大变形与材料破坏问题的一种有效数值分析方法.为了研究层裂问题,论文将质点失...交错网格物质点法(Staggered Grid Material Point Method,SGMP)有效地消除了物质点法(Material Point Method,MPM)的跨网格数值误差,是模拟冲击爆炸等涉及大变形与材料破坏问题的一种有效数值分析方法.为了研究层裂问题,论文将质点失效模型引入交错网格物质点法中,对Hopkinson杆碰撞、飞片撞击靶板碰撞和混凝土受爆炸载荷冲击等层裂问题进行了数值模拟研究,结果表明SGMP可以很好地模拟层裂问题.展开更多
Railfan gets up at 4:30 a.m.to get on the first train"I got up at 4:30 this morning and took a taxi from my home to the Wuhan East Railway Station.I just wanted to be on the first train departing there,"said...Railfan gets up at 4:30 a.m.to get on the first train"I got up at 4:30 this morning and took a taxi from my home to the Wuhan East Railway Station.I just wanted to be on the first train departing there,"said Xia Fengzhang,a sophomore at Wuhan Railway Bridge Vocational College.He arrived at the station's waiting hall at 5:30 a.m.展开更多
At Lingshan Hill,Jiangxia District,there is a flying waterfall as well as rapeseed fields,and a lake in a scenic area that will open for trial operation in March.It is said that the place was once the location of an a...At Lingshan Hill,Jiangxia District,there is a flying waterfall as well as rapeseed fields,and a lake in a scenic area that will open for trial operation in March.It is said that the place was once the location of an abandoned mine.How did it turn into such a beautiful location?Come and learn about its story.展开更多
From April 20,passengers have been able to use.WeChat's Public Transit Cards function to take buses on more than 500 routes,covering more than 8,000 buses.Passengers simply need to open the WeChat mini-program&qu...From April 20,passengers have been able to use.WeChat's Public Transit Cards function to take buses on more than 500 routes,covering more than 8,000 buses.Passengers simply need to open the WeChat mini-program"乘车码"(cheng che ma),activate the"武汉公交乘车码"(wu han gong jiao cheng che m),then scan the QR code to take a bus.The fare will be automatically deducted from the passenger's WeChat wallet.展开更多
At the Hanyang Test Site of the Institute of Hydroecology under the Ministry of Water Resources and the Chinese Academy of Sciences,many baby Chinese sturgeons,several centimeters long,are happily swimming about and f...At the Hanyang Test Site of the Institute of Hydroecology under the Ministry of Water Resources and the Chinese Academy of Sciences,many baby Chinese sturgeons,several centimeters long,are happily swimming about and feeding.Dr.Liao Xiaolin at the institute said that this batch of 65,000 Chinese sturgeons was born over 50 days ago and were growing steadily.This is the first time that the 2.5-generation of Chinese sturgeons have been bred in an artificial environment in China,and marks a major step for the protection of this variety。展开更多
基金supported by the China Postdoctoral Science Foundation(Nos.2021T140151,2021M690820)the National Natural Science Foundation of China(No.52001099)the Shanghai Aerospace Science and Technology Innovation Fund,China(No.SAST2020-108).
文摘Volumetric defects in high-strength aluminum alloy components were repaired via friction stir remanufacturing(FSR).Various consumable pins made of AA7075-T6 were designed.Top diameters of the consumable pins afected material fow,which ensured that the materials at the repairing interface were forged to metallurgical bonding.Conical angles determined load transfer besides material fow,which afected the fracture of the pins before the dwelling stage.Sound repaired components were achieved when the conical angle of the consumable pin was 1°larger than that of the volumetric defect.The ultimate tensile strength and elongation of the repaired components reached 445.9 MPa and 9.6%,respectively.The design criteria of the consumable pin in the FSR was established,which provided valuable references to repair volumetric defects in high-strength aluminum components.
基金supported by the National Natural Science Foundation of China(Nos.51003018 and 21374009)Program of International S&T Cooperation Special Project(No.2011DFR50770)the Fundamental Research Funds of the Central University(No.HEUCFJ161003)
文摘Hydrogen bonding is considered to have significant effect on the interaction between polymeric chains and on the viscoelasticity of the polymeric materials. In this paper, we attempt to discuss the relationship between hydrogen bonding density and damping behavior and mechanical properties of polyethylene-based polymeric materials. For this reason, a series of pendant chain hydrogen bonding polymers （PCHBP） with different hydrogen bonding density （HBD） were prepared by quantitatively changing the content of pendent hydroxyl groups on the main chain of polyethylene. It was found that PCItBP with low HBD showed similar properties to polyethylene, indicating that the property of the materials was dependent mainly on the structure of the main chain. However, PCHBP with high HBD exhibited two tandpeaks and a platform of loss modulus as well as a high storage modulus （about 400 MPa） at the second tand peak temperature, demonstrating that a polymeric material with high strength and damping properties was obtained. More importantly, the maximum of loss modulus showed a linear increase with the HBD, indicating that a higher HBD greatly improved the damping properties of the polymeric materials.
文摘交错网格物质点法(Staggered Grid Material Point Method,SGMP)有效地消除了物质点法(Material Point Method,MPM)的跨网格数值误差,是模拟冲击爆炸等涉及大变形与材料破坏问题的一种有效数值分析方法.为了研究层裂问题,论文将质点失效模型引入交错网格物质点法中,对Hopkinson杆碰撞、飞片撞击靶板碰撞和混凝土受爆炸载荷冲击等层裂问题进行了数值模拟研究,结果表明SGMP可以很好地模拟层裂问题.
文摘Railfan gets up at 4:30 a.m.to get on the first train"I got up at 4:30 this morning and took a taxi from my home to the Wuhan East Railway Station.I just wanted to be on the first train departing there,"said Xia Fengzhang,a sophomore at Wuhan Railway Bridge Vocational College.He arrived at the station's waiting hall at 5:30 a.m.
文摘At Lingshan Hill,Jiangxia District,there is a flying waterfall as well as rapeseed fields,and a lake in a scenic area that will open for trial operation in March.It is said that the place was once the location of an abandoned mine.How did it turn into such a beautiful location?Come and learn about its story.
文摘From April 20,passengers have been able to use.WeChat's Public Transit Cards function to take buses on more than 500 routes,covering more than 8,000 buses.Passengers simply need to open the WeChat mini-program"乘车码"(cheng che ma),activate the"武汉公交乘车码"(wu han gong jiao cheng che m),then scan the QR code to take a bus.The fare will be automatically deducted from the passenger's WeChat wallet.
文摘At the Hanyang Test Site of the Institute of Hydroecology under the Ministry of Water Resources and the Chinese Academy of Sciences,many baby Chinese sturgeons,several centimeters long,are happily swimming about and feeding.Dr.Liao Xiaolin at the institute said that this batch of 65,000 Chinese sturgeons was born over 50 days ago and were growing steadily.This is the first time that the 2.5-generation of Chinese sturgeons have been bred in an artificial environment in China,and marks a major step for the protection of this variety。
