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Experimental and Numerical Research on Deformation Behavior of Thin-Walled and Large Expansion Ratio Guide Vane Liner in Hydroforming Process
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作者 Pengzhi Cheng Lihui Lang +3 位作者 Yulong Ge Shangwen Ruan Xinmin Duan Tianwei Shao 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2015年第4期1-9,共9页
Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately ... Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately 0. 01,and the maximum expansion ratio( Dmax/ OD) of the needed part is more than 40%,and the length to diameter ratio of the expansion regionis more than 3. 0. It is very hard to manufacture this kind of ultra-thin-wall,curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle-wrinkles need bigger axial force than tube-end-wrinkles and feeding-wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough. With the increase of the axial and hoop stress ratio,the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment.The process is feasible and the finished part is qualified. 展开更多
关键词 tube hydroforming super alloy ultra-thin-wall large expansion ratio useful wrinkle plastic buckling critical buckling stress
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Mechanical analysis of folds in compressive belt and its significance to earthquakes
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作者 谢新生 《Acta Seismologica Sinica(English Edition)》 EI CSCD 1999年第3期306-313,共8页
The paper proposes the conception of Beads type fold system. The mechanical analyses of the typical tectonic system are made by means of elastic stability theory, mathematical and mechanical method and rheology. The... The paper proposes the conception of Beads type fold system. The mechanical analyses of the typical tectonic system are made by means of elastic stability theory, mathematical and mechanical method and rheology. The relation among the deflections of folds and time, external forces, and distribution of stresses, strain energy density are analyzed to explain the causing mechanism of folding earthquake. 展开更多
关键词 Beads type fold system critical stress of buckling ratio of minor and major fold axesviscoelasticity folding earthquake
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Influence of the connecting condition on the dynamic buckling of longitudinal impact for an elastic rod
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作者 Xiaojuan Jiao Jianmin Ma 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2017年第3期291-298,共8页
The stress wave propagation law and dynamic buckling critical velocity are formulated and solved by considering a general axial connecting boundary for a slender elastic straight rod impacted by a rigid body. The infl... The stress wave propagation law and dynamic buckling critical velocity are formulated and solved by considering a general axial connecting boundary for a slender elastic straight rod impacted by a rigid body. The influence of connecting stiffness on the critical velocity is investigated with varied impactor mass and buckling time. The influences of rod length and rod mass on the critical velocity are also discussed. It is found that greater connecting stiffness leads to larger stress amplitude, and further results in lower critical velocity. It is particularly noteworthy that when the connecting stiffness is less than a certain value, dynamic buckling only occurs before stress wave reflects off the connecting end. It is also shown that longer rod with larger slenderness ratio is easier to buckle, and the critical velocity for a larger-mass rod is higher than that for a lighter rod with the same geometry. 展开更多
关键词 Elastic rod Longitudinal impact Connecting boundary Stress wave Dynamic buckling critical velocity
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