In this talk, we present a recent and a major development on atomistic-informed multiscale simulations of plastic deformation in crystalline and amorphous solids.

In the first part, we shall discuss a recently developed multiscale dislocation pattern dynamics called Multiscale Crystal Defect Dynamics (MCDD), in which we develop a systematic approach that uses a generic early dislocation pattern in crystals and the mixed order Cauchy-Born rules to establish an atomistic-informed crystal plasticity.   The main novelties of MCDD-based crystal plasticity are: (1) We have discovered a multiscale quasi-crystal patterns for geometrically-necessary 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 we can simulate single crystal plasticity at sub-micro level or even higher levels. MCDD theory is an atomistic-informed macroscale or multiscale modeling theory that does not require any empirical formalism in the material theory.

In the second part of this talk. we shall introduce the development of the Multiscale Shear-Transformation-Zone (STZ) theory that can simulate plastic deformation in amorphous solids. In the multiscale STZ theory, we develop a concept the representative sampling cell (RS-cell) to extend the notion of the unit cell in crystalline materials to amorphous solids. Moreover, we have developed a coarse-grained Parrinello-Rahman molecular mechanics-based Cauchy-Born rule, and combining it with the RS-cells, we have successfully simulated plastic deformations in a Lennard-Jones binary solid, a benchmark amorphous solid, including the yield stress, flow stress, the Bauschinger effect, and plasticity under cyclic loadings, etc. at macroscale level without any empirical material parameters.

Dr. Shaofan Li, currently a full professor of applied and computational mechanics at the University of California-Berkeley. Dr. Li graduated 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 a 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 IACM (International Association of Computational Mechanics) Fellow Award [2017]; Distinguished Fellow Award of ICCES [2014]; ICACM Computational Mechanics Award [2013], USACM Fellow Award (2013), A. Richard Newton Research Breakthrough Award [2008], and NSF Career Award [2003]. 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.