December 5, 2018
Abstract: In this presentation, we shall discuss a recently developed multiscale dislocation pattern dynamics that is called Multiscale Crystal Defect Dynamics (MCDD), in which we put forth a notion of the geometrically compatible dislocation pattern (GCDP), and we have developed a geometric approach to construct the geometrically compatible dislocation pattern (GCDP). By postulating that GCDP is the dominant dislocation pattern at early stage, we have formulated a multiscale dislocation pattern dynamics, by combining GCDP with the higher order Cauchy-Born rules, which naturally leads an atomistically informed crystal plasticity.
The main novelties of MCDD-based crystal plasticity are: (1) We have discovered a multiscale quasi-crystal patterns for geometrically-compatible dislocations, which is related to the original crystal structure, and (2) We adopt a fourth-order (four scales) Cauchy-Born rule-based strain gradient theory to model constitutive behaviors of various dislocation patterns, and (3) we have successfully simulated single crystal plasticity at sub-micro level or even higher levels by using MCDD based multiscale crystal plasticity finite element method. The main advances of MCDD method are: (1) We can simulate crystal plasticity by using mixed order hyperelastic strain gradient constitutive relation, and (2) MCDD clearly elucidates the dislocation pattern junction, which may provide insights into dislocation mobility and interactions.
Bio: Dr. Shaofan Li is currently a full professor of applied and computational mechanics at the University of California-Berkeley. Dr. Li graduated from the East China University of Science and Technology (Shanghai, China) with a BS degree in 1982; he also holds MS Degrees from both the Huazhong University of Science and Technology (Wuhan, China) and the University of Florida (Gainesville, FL, USA) in 1989 and 1993 respectively. In 1997, Dr. Li received a PhD degree 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 is the recipient of IACM Fellow Award ; Distinguished Fellow Award of ICCES ; ICACM Computational Mechanics Award , USACM Fellow Award (2013), A. Richard Newton Research Breakthrough Award , and NSF Career Award . Dr. Li has published more than140 articles in peer-reviewed scientific journals (SCI) with h-index 42 (Google Scholar), and he is also the author of two research monographs/graduate textbooks.