香港大学工程学院颜庆云教授讲学通知

应我校材料科学与工程学院黄永江副教授邀请，香港工程科学院Fellow，香港大学工程学院颜庆云教授近日将来我校访问，并进行学术讲座，欢迎感兴趣的老师同学参加。

报告人简介：

颜庆云教授现为香港大学教授，香港工程科学院Fellow，力学领域顶级期刊International Journal of Plasticity副主编，在金属材料的力学性能-结构相关性、薄膜材料的力学性能、力学性能表征、位错理论、原子尺度金属材料的结构特征、金属材料的缺陷理论及仿真等方面在国际上享有盛誉。在国际高水平期刊发表学术论文220余篇，被引用4500余次，H因子达35。

报告一

题目：Introduction to PhD Studies at the University of Hong Kong

时间：2019年10月28日下午13:30-18:00

地点：邵馆2楼205报告厅

摘要：Mechanics and materials teaching and research at HKU dates back to 1912 when the university opened its door to students. In modern times, the Department of Mechanical Engineering at HKU is engaged in an exciting spectrum of research areas in materials engineering. In this short talk, a brief introduction of PhD studies at HKU will be given by Prof. Ngan.

报告二

题目： Open electrodeposition of stimuli-responsive metal hydroxides/oxides for direct fabrication of origami micro-robots

时间：2019年10月28日下午13:30-18:00

地点：邵馆2楼205报告厅

摘要：Flexible origami structures can mimic the complicated motions of small creatures that are otherwise difficult to be achieved by rigid robots with limited degree of motion freedom. However, actuating origami structures in a compact and self-contained way has been a critical challenge. Here, we demonstrate a versatile approach of actuating origami micro-robots, by printing self-folding creases on compliant polymer membrane substrates. The self-folding creases are made of a type of stimuli-responsive transition metal hydroxides/oxides that can undergo large actuation under electrochemical or light stimulations. Direct printing of the stimuli-responsive material via a microfluidic electrochemical writing method at the locations of the creases enables the creases to self-fold independently “on demand”, with folding curvatures exceeding 1 mm^-1 under low-intensity visible-light stimulation in ambient conditions, or low-potential electrochemical stimulation in electrolytic environments, with response time as fast as in seconds. Based on the high performance of such active creases, complex miniaturized origami designs powered by hinges activated in an independently controllable way are demonstrated, including self-folding Miura and a full micro-robotic hand with independently programmable finger joints. These results prove a new, versatile paradigm for micro-robotics, where a transferrable approach is applicable to design and fabricate a wide variety of customizable micro-robots with compact construction and complex motions using different stimuli-responsive ceramic-based materials.

报告三

题目：Some new progresses concerning glass and crystalline plasticity modeling

时间：2019年10月28日下午13:30-18:00

地点：邵馆2楼205报告厅

摘要：Modeling of plasticity in both glass and crystalline materials is a challenging topic. This seminar reports recent progresses made in the modeling of plasticity in both glasses and crystalline solids.

In the first part of this seminar, the framework of a glass plasticity model is outlined, which focusses on the stochastic and yet correlated operation of shear transformation zones (STZs). The model is based on the premise that prior operation of STZs triggers the emergence of new ones, and hence successive occurrence of discrete shear events may speed up rapidly, leading to shear localization in the form of shear bands. A new framework of glass plasticity simulator is therefore obtained by relating the probability of the successive operation of discrete STZs to their nucleation density, the growth law of which is governed by applied stress and history factors.

The second part of the seminar addresses dislocation plasticity in crystalline solids. Within the concept of “continuous dislocation dynamics” (CDD), dislocation densities, rather than individual dislocation segments as in “discrete dislocation dynamics”, are modeled to predict mesoscale plasticity behaviours. Here, a simple evolution equation for dislocation densities moving on a slip plane is introduced. This equation gives the time evolution of dislocation density at a general field point on the slip plane, due to the approach of new dislocations and tilting of dislocations already at the field point. This equation is fully consistent with Acharya’s evolution equation and Hochrainer et al.’s CDD theory, but it is much simpler to implement numerically. In particular, it is shown that the variable of dislocation curvature is unnecessary if one considers one-dimensional flux divergence along the dislocation velocity direction.

颜庆云教授个人主页： http://hub.hku.hk/cris/rp/rp00225!

For feedback from a graduate of Prof. Ngan, please read:

http://epaper.southcn.com/nfdaily/html/2016-09/09/content_7581330.htm

Other media coverage of Prof. Ngan:

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769415003243

https://www.youtube.com/watch?v=RYypGmLFjQM&feature=youtu.be

https://interestingengineering.com/engineers-invent-new-actuating-material-that-can-replace-motors-in-future-robots

Prof. Ngan is recruiting PhD students for the following project areas颜教授拟从如下方向招收博士生: