Measuring the strength of ductile microparticles at extreme strain rates

Abstract

We propose a method using high-velocity ballistic impacts of deformable microparticles on a rigid target to assess particle strength at strain rates exceeding 10⁶/s. High-speed imaging allows us to view particle behavior in-situ, which is then compared to models to elicit insight into plasticity. Over a range of velocities, the power-law decline of the rebound velocity permits fitting with a single dynamic yield strength, which finite element analysis shows matches well with the average strength of the particle over the duration of the impact, even as it experiences large strain and strain-rate hardening.