Modeling of dynamic elasto-plastic growth of a nano-void with surface energy, inertia and thermal softening effects

Abstract

Surface effect, inertia and thermal softening are important factors affecting the elasto-plastic evolution of voids. In this study, we theoretically examine the dynamic evolution of a nano-void in an elasto-plastic medium, particularly focusing on influences of surface energy, inertia and thermal softening. A two-stage strategy of analyzing surface effect is adopted, i.e. the first stage which is a quasi-static stage from a fictitious stress-free configuration to the actual initial configuration, and the second one which is the dynamic process of deformation under both surface stress and external dynamic loadings. The void will grow dynamically and quickly under high external loading, and the accelerations of material points in the neighborhood of the void are extremely high, resulting in a profound inertia effect. Under impact-like loading conditions, the plastic work done during the elasto-plastic growing process of the void is mainly transformed into heat, leading to thermal softening of material. Furthermore, heat transfer can be well neglected due to the transient characteristic of the problem studied. Tendencies related to all above influence factors are systematically analyzed.