Continuum mesoscale modelling of nanocrystalline fcc metals under shock-loading using an spectral formulation fed by molecular dynamics results

Abstract
In this paper we present a micromechanical approach based on Fast Fourier Transforms to study the role played by dislocation glide and grain boundary (GB) accommodation in the determination of the yield strength of nanostructured materials under shock. For this, we construct unit cells representing self-similar polycrystals with different grain sizes in the nanometer range and use local constitutive equations for slip and grain boundary accommodation. We study the effect of grain size and shock pressure on the local and effective behavior of nanostructured fcc materials with parameters obtained from experiments and atomistic simulations. Predictions of a previous pressure-sensitive model for the effective yield strength behind a shock front are improved by considering strain partition between slip and GB activity.