报告题目：

Grazing Induced Bifurcations: Innocent or Sinister?

报告人：

Professor Marian Wiercigroch

Centre for Applied Dynamics Research, School of Engineering，University of Aberdeen, UK

报告时间：

4月28日（周五） 9:30

报告地点：

第七教学楼C210

报告摘要：

This lecture will argue the nature of subtle phenomenon such grazing bifurcations occurring in non-smooth systems, which include the findings of a narrow band of chaos to the grazing condition and the abrupt onset to chaos caused by a dangerous bifurcation.The experimentally observed bifurcations are explained theoretically using mapping solutions between locally smooth subspaces. In order to understand the observed bifurcation scenarios, a global analysis has been undertaken to investigate the influence of stable and unstable orbits which are born in distant bifurcations but become important at the near-grazing conditions. A good degree of correspondence between the experiment and theory fully justifies the adopted modelling approach. Specially, similar phenomena were observed for a rotor system with bearing clearances, which was analysed numerically and experimentally. To gain further insight into the system dynamics a path following method has been developed to unveil complex bifurcation structures often featuring dangerous co-existing attractors.

报告人简介：

Marian Wiercigroch教授，现为国际著名的应用动力学研究中心的创立者和负责人、英国阿伯丁大学六世纪主席、国际合作负责人；爱丁堡皇家学会院士（2009）、机械工程师学会会士（2009）、波兰Lodz工业大学荣誉博士（2013）、富布莱特奖获得者（1994）。Wiercigroch教授是理论和实验非线性动力学领域享誉世界的科学家，其专注于油气工程、故障诊断和振动控制、水声学、可再生能源、转子动力学、非线性振动等领域科学问题的研究；已经发表350余篇期刊和会议论文，现为国际著名杂志《International Journal of Mechanical Sciences》的主编，并担任《Acta Mechanica Sinica》、《International Journal of Non-linear Mechanics》等多个国际学术期刊的编委，多次担任国际会议主席或组织者。

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