Modeling the influence of grain-level matrix inhomogeneity on strain localization in the presence of hard particles

The influence of grain-level matrix inhomogeneity on strain localization in sheet metals has been studied using a two-dimensional plane stress model containing two hard particles by finite element analysis. When the matrix material is treated as a homogeneous continuum, the localization strain decreases with interparticle spacing for particles aligned along the loading direction. In the case of an inhomogeneous matrix, consisting of grains of different Taylor factors corresponding to different crystallographic orientations, the position of the localization band and the value of localization strain seem to be insensitive to the interparticle spacing. Instead, localization forms preferentially in the softer grains within the matrix. The amount of post-localization deformation decreases significantly when the two particles straddle the shear band. It is concluded that the stress concentration that develops between two closely spaced particles does influence the shear localization process but the matrix inhomogeneity dominates localization behavior during sheet metal deformation.