Void-nucleation vs void-growth controlled plastic flow localization in materials with nonuniform particle distributions

Plastic flow localization may occur after significant void growth or immediately after void nucleation. In the present work, a model is developed to investigate the role of nonuniform particle distributions (e.g. random distribution, clusters) in plastic flow localization. A parameter is developed to quantitatively determine whether localization is predominantly controlled by void-nucleation or by void-growth. It is established that, for large clusters of particles, localization is more likely to be initiated by void nucleation, while it is dominated by void growth for small clusters. Both critical strain and stress void-nucleation criteria are investigated. It is observed that void-nucleation governed by the critical stress criterion initiates plastic flow localization at a much lower strain level than that governed by the critical strain criterion.