The failure and fragmentation of ductile materials

Abstract

The failure and fragmentation of ductile materials is important to the understanding of key structural materials. Ductile materials fail through the nucleation, growth, and coalescence of voids. A numerical study has been developed which couples these key stages of ductile failure, an elastic-viscoplastic material model and wave propagation. The governing equations are integrated through the method of characteristics allowing for the dynamic propagation of waves in the sample and the communication of information thereby such simulations are utilized to predict failure spacing in a ductile material within a uniaxial strain approximation. The final failure spacing is a function of the complex interaction of loading and stress release that accompanies the localization of damage and eventual fracture of material. The average fragment size predicted by the model exhibits two regimes as the rate of loading increases. At low strain rates, a plateau is evident in which the average fragment size shows strong dependence on material properties but little dependence on loading rate. In the high strain rate regime, inertia begins to dominate as the average fragment size decreases with strain rate but has little dependence on the material.