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Geometrically-Compatible Dislocation Pattern and Simulations of Plastic Deformations in Crystalline and Amorphous Materials
14 Dec
14. December 2018 17. December 2018
short course (2 days)

Geometrically-Compatible Dislocation Pattern and Simulations of Plastic Deformations in Crystalline and Amorphous Materials

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

In the first part of the talk, we shall discuss a recently developed multiscale dislocation pattern dynamics called Multiscale Crystal Defect Dynamics (MCDD), in which we put forth a novel concept of Geometrically-consistent dislocation pattern. Based on this notion and higher order Cauchy-Born rule, we have developed a systematic approach that uses the generic geometrically-compatible dislocation pattern in crystals to establish a multiscale crystal plasticity formulation, or an atomistic-informed crystal plasticity.

The main novelties of MCDD-based crystal plasticity are: (1) We have discovered a multiscale quasi-crystal patterns to represent geometrically-necessary dislocation pattern distribution, 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 crystal defects, 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 a recent development of the Multiscale Shear-Transformation-Zone (STZ) theory that can simulate plastic deformation in amorphous solids. In the multiscale STZ theory, we developed a concept of 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 by combining it with the RS-cells, we have successfully simulated plastic deformations in a Lennard-Jones binary solid, a benchmark amorphous solid, at macroscale including the yield stress, flow stress, the Bauschinger effect, and plasticity under cyclic loadings, etc. at macroscale level without any empirical material parameters.

Speaker

Prof. Shaofan Li
Department of Civil and Environmental Engineering
The University of California-Berkeley

Organiser

The Graduate School MUSiC with the Sofja Kovalevskaja – Research Group

Date

14. December 2018 17. December 2018
10:30 o'clock - 16:30 o'clock

Deadline

10. December 2018

Public contact

Xiaoying Zhuang
Institut für Kontinuumsmechanik
Appelstr. 11 A
30167 Hannover
Tel.: 0511 762 17834
Fax: 0511 762 5496
schulte@ikm.uni-hannover.de

Location

Graduiertenschule MUSiC
Building: 3403
Room: A501
MUSiC Seminarraum
Appelstr. 11 A
30167 Hannover
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