2020学年第1期学术报告会

中法核工程与技术学院2020学年第1期学术报告会

Sino-French Institute of Nuclear Engineering and Technology 1^st Academic Seminar of 2020 School Year

Topic: New insight into material strength and nonequilibrium energy model

Speaker: Professor WANG Biao

Date: Friday, September 18th, 2020

Time: 12:40-13:40

Venue: F309, Zhuhai Campus

Host: Professor WANG Wei

Abstract

How to define and determine material strength has long been an important academic issue since Leonardo da Vinci ’s time. Driven by various engineering applications, the strength theory has a history of about 500 years. Modern strength theory is based on the concept of stress and strain. The strength parameters can be characterized through simple tests on small samples and the mechanical behavior of a large structure can then be predicted by an appropriate strength theory. However, it is found that the classical strength theories fail to predict the behavior of structures reliably and people have to use large safety factors and conservative designs. Great progress is made by fracture mechanics but the deficiency of the classical strength theories is manifested again. For example, the material still remains intact if a small crack exists even the stress at the crack tip is infinitely large. This hints that stress itself is not enough to describe the driving force of fracture. Besides, the size effect of material strength yet cannot be explained by the traditional strength theory. These observations call for new insights into the strength and the failure of materials. In fact, the failure process is an irreversible process during which some atoms pass some other atoms. This process can be described by a nonequilibrium process whose kinetics can be formulated by the failure mechanism. New theory of material strength can be built by seeking the equilibrium state of the evolution equation. It is interesting to see that the new theories are consistent with the classical strength theories under many cases. This means that material failure should be examined from a global view. Based on local stress and strain, the classical strength theories have inherent weakness. By applying the new theory, the size effect of the strength of nanocrystals and other ideal materials is examined in depth.

About the speaker

Professor WANG Biao is a double employed professor in the School of Physics and the Sino-French Institute of Nuclear Engineering and Technology of Sun Yat-sen University. He is a national high-level talent of the Ministry of Education and a winner of the Fund of National Natural Science Foundation for Excellent Young Investigators. His research areas are mainly about (1) nuclear structure and nuclear material mechanics; (2) simulation and safety of nuclear structure; (3) physics and mechanics of micro/ nano materials; (4) laser crystal materials and preparation. In these areas, he has published over 400 international journal papers and two books, and gained over 50 authorized patents. From 2014 to 2019, he was shortlisted as the Most Cited Chinese Researchers. He joined Sun Yat-sen University in Guangzhou as the First Level Talents in 2004, and he had served as the Dean of the School of Physics and Engineering from October 2005 to January 2014. He played a leading role in the establishment of the Sino-French Institute of Nuclear Engineering and Technology, and since 2010, he has worked as the Dean of the Institute until June 2020. As a principal investigator, he has been supported by key projects of National Natural Science Foundation of China (in 2018, 2012, 2007), 863 research plan of the Ministry of Science and Technology and major basic research program of the Commission of science, technology and industry for national defense. Over these years,  he received dozens of domestic and international academic awards, such as “Citation Classic Award” by ISI (2000), outstanding talents of "Guangdong special support program" in 2019 (south Guangdong Baijie), the Fifth China Youth Science and Technology Award (1997), Winner of the first prize of Science & Technology Award of Guangdong Province of China (2007, ranked first), Winner of the 1st prize of Science & Technology Achievement Award of Ministry of Education of China (2004 , ranked first), Recipient of Special Allowance from State Council (2001), Ding Ying Technology Award of Guangdong Province of China (2010)and Chinese doctoral degree winner with outstanding contributions (1991), etc. Additionally, he is also a member of the Teaching Steering Committee for nuclear engineering and technology of the Ministry of education, chairman of the Guangdong physical society, executive director of the Chinese mechanical society, and editorial board member of several domestic and foreign academic journals, such as science of China.