Laurent Capolungo1 John Graham2 Ricardo Lebensohn1 Richard LeSar2

1, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
2, Iowa State, Iowa, Iowa, United States

A novel Fast Fourier Transform based discrete dislocation dynamics tool is introduced to study plasticity in polycrystalline media and is used to assess the predictive capability of advanced constitutive models to account for the effects of localized strain gradients, resulting from the interactions between dislocations and grain boundaries, on plastic deformation. To this end, discrete dislocation dynamics simulations of plastic deformation in aluminum polycrystals are performed and the ability of dislocation to cross grain boundaries is modulated such as to vary the level of strain localization within the system. In parallel a continuum level Fast Fourier Transform based elasto –viscoplastic strain-gradient crystal plasticity model is used to replicate the simulations performed with discrete dislocation dynamics. The two approaches are then directly compared. In particular, the advantages and shortcomings of hierarchical and concurrent multi-scale modeling frameworks are discussed.