A method of concurrent coupling of planar discrete dislocation plasticity (DDP) and a crystal plasticity
finite element (CPFE) method was devised for simulating plastic deformation in large polycrystals with
discrete dislocation resolution in a single grain or cluster of grains for computational efficiency;
computation time using the coupling method can be reduced by an order of magnitude compared to
DDP. The method is based on an iterative scheme initiated by a sub-model calculation, which ensures
displacement and traction compatibility at all nodes at the interface between the DDP and CPFE
domains. The proposed coupling approach is demonstrated using two plane strain problems: (i)
uniaxial tension of a bi-crystal film and (ii) indentation of a thin film on a substrate. The latter was also
used to demonstrate that the rigid substrate assumption used in earlier discrete dislocation plasticity
studies is inadequate for indentation depths that are large compared to the film thickness, i.e. the
effect of the plastic substrate modelled using CPFE becomes important. The coupling method can be
used to study a wider range of indentation depths than previously possible using DDP alone, without
sacrificing the indentation size effect regime captured by DDP. The method is general and can be
applied to any problem where finer resolution of dislocation mediated plasticity is required to study
the mechanical response of polycrystalline materials, e.g. to capture size effects locally within a larger
elastic/plastic boundary value problem.