学术报告：Auxetic Behaviour of Re-entrant Cellular Structured and graphene Kirigami at Nanoscale
报告题目：Auxetic Behaviour of Re-entrant Cellular Structured and graphene Kirigami at Nanoscale
报 告 人：秦庆华 教授
Some typical two-dimensional (2D) materials are active elements used in nano-electro-mechanical systems (NEMS) design, owing to their excellent in-plane physical properties on mechanical, electrical and thermal aspects. Considering a component with negative Poisson’s ratio used in NEMS, the adoption of kirigamis made of periodic re-entrant honeycomb structures at nanoscale would be a feasible method. The focus of this thesis work is to investigate the specific auxetic behaviour of this kind of structures from typical tailored 2D materials. By employing the numerical simulation method: molecular dynamics simulation, the auxetic behaviour of re-entrant cellular structured kirigami is discussed thoroughly and concretely.
Three main effects of a re-entrant cellular structured kirigami are discussed here. They are size effect, surface effect and matrix effect of 2D materials. The study begins with a demonstration that a kirigami with specific auxetic property obtained by adjusting the sizes of its honeycombs. Making use of molecular dynamics experiments, the size effect on auxetic behaviour of the kirigami is discussed. The results show that, in some cases, the auxetic difference between the microscopic structured kirigami and macroscopic structure kirigami is negligible, which means the results from macro-kirigami could be used to predict the auxetic behaviour of nano-kirigami. Surface effect of kirigami is also illustrated from two aspects. The one is to identify the difference of mechanical responses between pure kirigami and hydrogenated kirigami at some geometry and loading condition. And another is from the difference of mechanical responses between microstructure kirigami and continuum kirigami under the same loading condition and geometric configuration. Graphene is selected as the major 2D material in the study. As kirigami tailored from various 2D materials would exhibit different mechanical behaviour, graphene, single-layer hexagonal boron nitride (h-BN) and single-layer molybdenum disulphide (MoS2) are selected as representative 2D materials to investigate the influence of this effect, without loss of generality.
秦庆华教授，于1984年和1990年获华中科技大学固体力学专业硕士和博士学位，1994年获DAAD—王宽诚基金赴德国Stuttgart大学访问研究。1995年-1997年到清华大学作博士后研究；1997和2002年分获澳大利亚研究理事会Queen Elizabeth II 研究员和Professorial Fellow位置，2004年至今在澳大利亚国立大学工学院担任教授、副院长（2011-2013）、研究中心材料加工制造组的带头人等职位。2000年被聘为华中科技大学客座教授；2002年被天津大学聘为长江学者特聘教授。在应用力学领域，已发表300多篇期刊论文，出版7部专著，获得澳大利亚科学院颁发的J. G. Russell奖。