Nucleation of dislocations beneath a plane strain indenter

We examine the conditions for dislocation nucleation beneath a plane strain rectangular indenter using atomistic simulations as well as analytic model s, with the aim of (a) examining the validity of the analytic models and (b ) extracting a nucleation criterion that can be used in mesoscopic dislocat ion dynamics models. Atomistic lattice statics calculations are performed u sing the quasicontinuum method, while the analytic analysis is carried out within the Rice-Thomson and Peierls-Nabarro frameworks. We find that both t he atomistic and analytic models suggest a stress-based nucleation criterio n. The features of the analytic models and quasicontinuum simulations are c ompared on the basis of the nucleation load and the incipient slip distribu tion. We find that the predictions of the analytical models are qualitative ly borne out by the atomistic simulations, though quantitatively they are l eft wanting. Improvements to the analytical models to achieve quantitative agreement with the atomistic results are suggested. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.