Investigation of dislocation density evolution during simulated metallic microparticle impacts*

Accurately modeling the rate-dependent plastic deformation of metals across a large

range of strain rates requires a comprehensive accounting of dislocation motion and evolution.

The newly developed analytical dislocation evolution model of Hunter and Preston, accounts for

a wide range of dislocation annihilation and nucleation mechanisms including: network storage,

Frank-Read sources, cross-slip, double cross-slip, mobile-immobile annihilation, grain boundary

storage, grain boundary nucleation, and shock induced nucleation. In conjunction with the mean

first passage time flow stress model, this new model is able to capture the plastic behavior of

polycrystalline FCC metals across a large range of loading regimes from quasi-static to shock

loading environments. These models have been recently implemented in Los Alamos National

Laboratory’s hydrodynamics research code, FLAG. Data from quasi-static, Hopkinson bar, and

flyer plate experiments are used to create material parameter sets. Then continuum scale

microparticle impacts are simulated in FLAG and compared to experimental observations.