ABSTRACT

We examine the conditions for dislocation nucleation beneath a plane strain
rectangular indenter using atomistic simulations as well as analytic models,
with the aim of (a) examining the validity of the analytic models and (b)
extracting a nucleation criterion that can be used in mesoscopic dislocation
dynamics models. Atomistic lattice statics calculations are performed using
the quasicontinuum method, while the analytic analysis is carried out within
the Rice-Thomson and Peierls-Nabarro frameworks. We find that both the
atomistic and analytic models suggest a stress-based nucleation criterion.
The features of the analytic models and quasicontinuum simulations are
compared on the basis of the nucleation load and the incipient slip
distribution. We find that the predictions of the analytical models are
qualitatively borne out by the atomistic simulations, though quantitatively
they are left wanting. Improvements to the analytical models to achieve
quantitative agreement with the atomistic results are suggested.