Cylindrical rings with thin wall and high web ribs(CRTWHWR)are widely used as the key load bearing structures such as rocket body and space station cabin in aerospace field.However,it is still difficult to efficiently...Cylindrical rings with thin wall and high web ribs(CRTWHWR)are widely used as the key load bearing structures such as rocket body and space station cabin in aerospace field.However,it is still difficult to efficiently manufacture CRTWHWR with high performance because of their extreme geometry with thin-walled skins,high web ribs and large size.In this paper,a novel radial envelope forming process is put forward to efficiently achieve the plastic forming of CRTWHWR with high performance.Firstly,the principle of radial envelope forming process is clarified.Then,an efficient design method for the tool motion and geometry is proposed based on the reverse envelope principle,i.e.,CRTWHWR is adopted to reversely envelope the tool and thus the tool which does not interfere with CRTWHWR can be efficiently obtained in a single operation.Finally,a reasonable 3D FE model of the radial envelope forming process of CRTWHWR is established and the radial envelope forming mechanism of CRTWHWR is comprehensively revealed.Through the FE simulation and experiments with material of plastic mud,a typical CRTWHWR with diameter of 300 mm,axial height of 192 mm,the maximum rib height of 25 mm,the minimum rib thickness of 3 mm and skin thickness of 5 mm is radial envelope formed,i.e.,the ratio of the maximum rib height to the minimum rib thickness reaches 8.33,the ratio of the maximum rib height to skin thickness reaches 5 and the ratio of diameter to the minimum rib thickness reaches 100.The above results verify that the proposed radial envelope forming process has great potentials in efficiently manufacturing CRTWHWR with extreme geometry.展开更多
收集Web of Science(Wo S)数据库的高被引撤销论文数据,分析其分布规律和引证特征。结果发现,TOP20%高被引撤销论文430篇,分布于31个国家,多学科领域最多,35种期刊>3篇。高被引撤销论文撤销时滞和撤销论文总被引频次相关性较弱(P=0.0...收集Web of Science(Wo S)数据库的高被引撤销论文数据,分析其分布规律和引证特征。结果发现,TOP20%高被引撤销论文430篇,分布于31个国家,多学科领域最多,35种期刊>3篇。高被引撤销论文撤销时滞和撤销论文总被引频次相关性较弱(P=0.014),和撤销前被引频次相关性较强(P=0.000)。期刊IF和撤销论文数量、撤销论文总被引频次、撤销论文篇均被引频次正相关(P=0.017、P=0.000、P=0.005)。撤销后年均被引频次低于撤销前(P=0.000)。本研究说明IF高的期刊发表的撤销论文对学术界带来的负面影响较大,撤销时滞延长增加了撤销前引用,撤销起到了一定的净化效果,但是净化效果还不理想,建议国内外学者加强对撤销论文及其不良影响的关注。展开更多
基金the National Natural Science Foundation of China(No.U2037204)the 111 Project(B17034)+1 种基金Innovative Research Team Development Program of Ministry of Education of China(No.IRT17R83)the National Natural Science Foundation of China(No.52005375)for the support given to this research。
文摘Cylindrical rings with thin wall and high web ribs(CRTWHWR)are widely used as the key load bearing structures such as rocket body and space station cabin in aerospace field.However,it is still difficult to efficiently manufacture CRTWHWR with high performance because of their extreme geometry with thin-walled skins,high web ribs and large size.In this paper,a novel radial envelope forming process is put forward to efficiently achieve the plastic forming of CRTWHWR with high performance.Firstly,the principle of radial envelope forming process is clarified.Then,an efficient design method for the tool motion and geometry is proposed based on the reverse envelope principle,i.e.,CRTWHWR is adopted to reversely envelope the tool and thus the tool which does not interfere with CRTWHWR can be efficiently obtained in a single operation.Finally,a reasonable 3D FE model of the radial envelope forming process of CRTWHWR is established and the radial envelope forming mechanism of CRTWHWR is comprehensively revealed.Through the FE simulation and experiments with material of plastic mud,a typical CRTWHWR with diameter of 300 mm,axial height of 192 mm,the maximum rib height of 25 mm,the minimum rib thickness of 3 mm and skin thickness of 5 mm is radial envelope formed,i.e.,the ratio of the maximum rib height to the minimum rib thickness reaches 8.33,the ratio of the maximum rib height to skin thickness reaches 5 and the ratio of diameter to the minimum rib thickness reaches 100.The above results verify that the proposed radial envelope forming process has great potentials in efficiently manufacturing CRTWHWR with extreme geometry.
文摘收集Web of Science(Wo S)数据库的高被引撤销论文数据,分析其分布规律和引证特征。结果发现,TOP20%高被引撤销论文430篇,分布于31个国家,多学科领域最多,35种期刊>3篇。高被引撤销论文撤销时滞和撤销论文总被引频次相关性较弱(P=0.014),和撤销前被引频次相关性较强(P=0.000)。期刊IF和撤销论文数量、撤销论文总被引频次、撤销论文篇均被引频次正相关(P=0.017、P=0.000、P=0.005)。撤销后年均被引频次低于撤销前(P=0.000)。本研究说明IF高的期刊发表的撤销论文对学术界带来的负面影响较大,撤销时滞延长增加了撤销前引用,撤销起到了一定的净化效果,但是净化效果还不理想,建议国内外学者加强对撤销论文及其不良影响的关注。
