Damage Progression and Fragmentation in Atomistic, Single Crystal Copper at High Strain Rates

We show a correlation between nanoscale damage and fragmentation length scale through atomistic simulations. We simulated homogeneously expanding perfect, single crystal copper at rates ranging from 1E+08 to 3E+10 s-1 and temperatures from 200 to 1000 K. Damage was quantified in terms of void number density, average void volume, and void volume fraction. We quantified fragmentation size in terms of a length scale parameter, the solid volume per void surface area. A-1⁄2 power law relationship between the fragment length scale and strain rate was observed following the predictions of Mott. The fragmentation length scale and the maximum void number density are strongly correlated for this damage mechanism. We can scale up the relationships between damage and fragmentation observed in the molecular dynamics simulations to motivate a continuum scale fragmentation model.