Collision and Rebounding of Circular Rings on Rigid Target

弹塑性圆环对刚性壁的撞击和反弹

 

T.X. Yu(余同希)

Department of Mechanical Engineering, Hong Kong University of Science and Technology,

Clear Water Bay, Kowloon, Hong Kong. 

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Abstract

 

     As a simple but fundamental structural member, a circular ring has attracted attentions in applied mechanics. Recently, Yu and Bao studied the large dynamic deformation of a free-flying circular ring made of elastic, perfectly plastic material after it impinges on a rigid wall with initial velocity V0, as well as the following rebound process. From a dimensional analysis, it is found that the problem is governed by two non-dimensional parameters, i.e. non-dimensional thickness ηh/R and non-dimensional impact velocity νV0/VY, where VYY/()1/2 denotes the yield velocity of the material. Within a domain of these two non-dimensional parameters a systematic finite element simulation has been conducted together with preliminary theoretical considerations.

     To verify the numerical and theoretic predictions, an experimental set-up for thin-walled metal rings to collide with a rigid target was designed, in which an undeformed ring sample was accelerated by a bullet fired from a gun barrel, and its speed was measured before it collided on the rigid target. The large deformation history of the ring sample and its rebounding process from the target were recorded by a high-speed video camera. The deformation mechanism and the coefficient of restitution after collision are then compared with the numerical prediction and the preliminary theoretical model. The methodology developed and the verified results are useful for further studies of the collisions of various free-flying structural members onto solid targets, such as those happened in ball games and in landing of aerospace vehicles.

Keywords:  Circular rings, Collision, Rebounding, Large deformation mechanism

 

余同希, 1964年北京大学数学力学系本科毕业,1968年北京大学数学力学系研究生毕业(导师:王仁院士),1983年获英国剑桥大学哲学博士(PhD)学位(导师:英国皇家学会院士W. Johnson教授)。1995年获英国剑桥大学科学博士(DSc,荣誉)。

    历任第一机械工业部所属工厂及研究所工程师(1970-1979),北京大学力学系教授、博士生导师(1984-1991),英国曼彻斯特理工大学(UMIST) 机械工程系教授(1991-1995)。1995年4月加入香港科技大学,任机械工程系讲座教授,并先后担任工学院副院长(1998-2000)、机械工程系系主任(2002-2007)、香港科技大学协理副校长(2006-2010)、霍英东研究院院长(2007-2010)。现为香港科技大学荣休教授、香港科技大学副校长(研究与研究生教育)的资深顾问(负责科研评估),浙江大学包玉刚讲座教授,宁波大学包玉刚讲座教授。同时,也是中国工程物理研究院、中科院力学所、中国科技大学、北京航空航天大学、西北工业大学、南京航空航天大学、四川大学、武汉大学、大连理工大学、北京理工大学、华南理工大学、香港城市大学、新加坡南洋理工大学等国内外十余所院校的顾问教授或客座教授。此外,受聘为北京理工大学的“爆炸科学与技术国家重点实验室”和大连理工大学的“工业装备结构分析国家重点实验室”的学术顾问。

    研究工作主要集中于冲击动力学、塑性力学、结构与材料的能量吸收、复合材料与多胞材料等领域。编写出版了《塑性力学》(2010年再版易名为《工程塑性力学》)、《工程材料及其力学行为》、《结构塑性动力学引论》及《冲击动力学》等四部教材;著有《塑性弯曲理论及其应用》,《塑性结构的动力学模型》和《材料与结构的能量吸收》等三部专著(都有英文版在国外出版);发表了学术期刊论文330篇(90%为SCI收录)、国际会议论文200篇、专利4项。获选为剑桥大学丘吉尔学院海外院士;美国机械工程师学会会士(Fellow)、英国机械工程师学会会士(Fellow)、香港工程师学会会士(Fellow);担任国际冲击工程学报(International Journal of Impact Engineering)副主编、国际机械科学学报(International Journal of Mechanical Sciences)的Co-editor,以及多种国际学术刊物的编委。曾任中国力学学会副秘书长(1986-1994)、香港力学学会理事长(2000-2002)和国际理论与应用力学学会(IUTAM)理事会的香港代表(2003-2010)。2001年获中国高校科学技术奖一等奖。

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