In order to investigate the springback rules, the variation characteristics of physical property and microstructure in bending creep age forming process, a series of creep forming tests of 2124 aluminum alloy were con...In order to investigate the springback rules, the variation characteristics of physical property and microstructure in bending creep age forming process, a series of creep forming tests of 2124 aluminum alloy were conducted based on three kinds of single and double curvature forming tools. The results show that the spingback rate would be the minimum under the optimal coupling conditions among the temperature, aging time and internal stress state of material. Difference exists in the two directions of the formed sample with double curvature, but the curvature variation keeps the same. Yield strength, ultimate tensile strength and fracture toughness of the double curvature formed sample appear to be higher than those of the single curvature formed sample under the same aging condition, but the elongation and the anisotropy are opposite.展开更多
In this paper we investigate the Einstein＇s hyperbolic geometric flow and obtain some interesting exact solutions for this kind of flow. Many interesting properties of these exact solutions have also been analyzed an...In this paper we investigate the Einstein＇s hyperbolic geometric flow and obtain some interesting exact solutions for this kind of flow. Many interesting properties of these exact solutions have also been analyzed and we believe that these properties of Einstein＇s hyperbolic geometric flow are very helpful to understanding the Einstein equations and the hyperbolic geometric flow.展开更多
基金Project(2010CB731700)supported by the National Basic Research Program of China
文摘In order to investigate the springback rules, the variation characteristics of physical property and microstructure in bending creep age forming process, a series of creep forming tests of 2124 aluminum alloy were conducted based on three kinds of single and double curvature forming tools. The results show that the spingback rate would be the minimum under the optimal coupling conditions among the temperature, aging time and internal stress state of material. Difference exists in the two directions of the formed sample with double curvature, but the curvature variation keeps the same. Yield strength, ultimate tensile strength and fracture toughness of the double curvature formed sample appear to be higher than those of the single curvature formed sample under the same aging condition, but the elongation and the anisotropy are opposite.
基金The project supported in part by the National Natural Science Foundation of China under Grant No. 10671124 and the Program for New Century Excellent Talents in University of China under Grant No. NCET-05-0390 Acknowledgments The author would like to thank the Center of Mathematical Sciences at Zhejiang University for the great support and hospitality and the referee for pertinent comments and valuable suggestions.
文摘In this paper we investigate the Einstein＇s hyperbolic geometric flow and obtain some interesting exact solutions for this kind of flow. Many interesting properties of these exact solutions have also been analyzed and we believe that these properties of Einstein＇s hyperbolic geometric flow are very helpful to understanding the Einstein equations and the hyperbolic geometric flow.
