New Line Model for Optimized Dislocation Dynamics Simulations
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New Line Model for Optimized Dislocation Dynamics Simulations Ronan Madec, Benoit Devincre and Ladislas P. Kubin Laboratoire d’Etude des Microstructures, CNRS-ONERA, 29 Av. de la Division Leclerc, B.P. 72, 92322 Ch tillon Cedex, France. ABSTRACT A new model for the discretisation of dislocation lines is presented, which is optimised for mesoscale simulations of dislocation dynamics. By comparison with the existing "edge-screw" model, the present one provides a better description of the stress field close to the dislocation lines. It simplifies the modelling of dislocation reactions and accelerates computations by allowing to make use of larger time steps. An application to attractive junctions and forest hardening is briefly sketched.
INTRODUCTION Ten years ago the first three-dimensional mesoscopic simulation of dislocation dynamics (DD) was proposed [1]. In the latter, a simplified description of dislocation core properties was combined with an elastic frame in order to model the dynamics of dense dislocation microstructures. The most noticeable aspect of this model was the geometrical solution proposed to discretise the dislocation lines [2]. Indeed, for the sake of computing efficiency, it was proposed to replace the continuous lines by a succession of discrete segments with edge and screw characters. This "edge-screw" simulation has been successfully used to study plastic deformation in different types of crystals, hence demonstrating its versatility (see ref.˚[3] for a short review). More recently, it has been coupled with a finite element code in order to deal with complex boundary value problems and/or complex loadings [4-5]. Other three-dimensional DD simulations have been developed in the past years [6-8]. They differ from the "edge-screw" model mainly in their geometrical formulation. The decomposition of a segment length and character is not performed on a finite set but in the continuum, in order to reproduce the line curvature as closely as possible. In spite of some technical complexities, this approach has the ability of better reproducing the elastic field close to the dislocation lines. Whatever the geometrical model considered, the computations have been restricted up to now to relatively small simulated volumes ~(15µm)3 and plastic strains (
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