主办单位：材料学院
报告题目：Multiscale Crystal Defect Dynamics and Simulations of Dislocation and Fracture
报告时间：2015年7月7日（周二）上午10：00
报告地点：5号楼502-1会议室
报告人：  Dr. Shaofan Li （University of California-Berkeley）
报告摘要：
Recently the author and his co-workers have developed an atomistic based multiscale crystal defect dynamics (MCDD), which is based on an interphase process zone model. In this work, we formulate a quasi-crystal model for defect formation in a perfect crystal solid, and this multiscale quasi-crystal defect dynamics model provides insights on dynamics behaviors of lattice defects and their evolutions. In particular, in this approach, we adopt various coarse grain materials models for both bulk media and material interphase or process zone. In bulk elements, the first order Cauchy-Born rule is adopted, so we can formulate an atomistic enriched continuum constitutive relation to describe the material behaviors. All the nonlinear deformations are assumed to be confined inside the process zone, and the process zone between the bulk elements is remodeled as a finite-width strip whose lattice constants and atomistic potential may be the same or different from those of the bulk medium. Inside the interphase zone, the higher order Cauchy-Born rules are adopted in process zones, and a higher order strain gradient-like coarse grain constitutive model is derived, which can capture the size-effect at the small scales. All interphase or process zones are constructed such that they are part (a subset) of slip planes in a lattice space.

The multiscale crystal defect dynamics has been applied to simulate both dislocation motion and crack propagations in both single crystals and polycrystals. We have employed the MCDD method to study and to simulate the impact and fragmentation of polycrystals and powder alloys under extreme conditions.

报告人简介：
Dr. Shaofan Li is currently a professor of applied and computational mechanics at the University of California-Berkeley. Dr. Li gradúate from the Department of Mechanical Engineering at the East China University of Science and Technology (Shanghai, China) with a Bachelor Degree of Science in 1982; he also holds Master Degrees of Science from both the Huazhong University of Science and Technology (Wuhan, China) and the University of Florida (Gainesville, FL, USA) in Applied Mechanics and Aerospace Engineering in 1989 and 1993 respectively. In 1997, Dr. Li received the PhD degree in Mechanical Engineering from the Northwestern University (Evanston, IL, USA), and he was also a post-doctoral researcher at the Northwestern University during 1997-2000.
In 2000, Dr. Li joined the faculty of the Department of Civil and Environmental Engineering at the University of California-Berkeley. Dr. Shaofan Li has also been a visiting Changjiang professor in the Huazhong University of Science and Technology, Wuhan, China (2007-2013).
Dr. Shaofan Li is the recipient of numerus awards including  A. Richard Newton Research Breakthrough Award from Microsoft Corp. (2008), and NSF Career Award (2003). Dr. Li has published more 100 articles in peer-reviewed scientific journals, and he is the author and co-author of two research monographs/graduate textbooks. Base don Google Scholar, Dr. Li has an h-index of 37 (as of May 2015).