A new hierarchical dislocation-grain boundary interaction model was developed in order to predict the mechanical behaviour of polycrystalline metals at micro- and sub-micro scales by coupling three-dimensional discrete dislocation dynamics simulation with the molecular dynamics simulation. At the microscale, the discrete dislocation dynamics simulations were responsible for capturing the evolution of dislocation structures; at the nanoscales, the molecular dynamics simulations were responsible for obtaining the grain boundary energy and ISF energy which were then transferred hierarchically to the discrete dislocation dynamics level. In the present model, four kinds of dislocation- grain boundary interactions, i.e. transmission, absorption, re-emission and reflection, were all considered. By this methodology, the compression of a Cu micro-sized bi-crystal pillar was studied. The characteristic mechanical behaviour of the bi-crystal was compared with that of the single crystal. Moreover, the comparison between the present penetrable model of a grain boundary and the conventional impenetrable model also demonstrated the accuracy and efficiency of the present model.

A Hierarchical Dislocation-Grain Boundary Interaction Model Based on 3D Discrete Dislocation Dynamics and Molecular Dynamics. Y.Gao, Z.Zhuang, X.C.You: Science China - Physics, Mechanics & Astronomy, 2011, 54[4], 625-32