Elucidating size effects on the yield strength of single-crystal Cu via the Richtmyer-Meshkov instability

Capturing the dynamic response of a material under high strain-rate deformation often demands challenging and time consuming experimental effort. While shock hydrodynamic simulation methods can aid in this area, a priori characterizations of the material strength under shock loading and spall failure are needed in order to parameterize constitutive models needed for these computational tools. Moreover, parameterizations of strain-rate-dependent strength models are needed to capture the full suite of Richtmeyer-Meshkov instability (RMI) behavior of shock compressed metals, placing an unrealistic demand for this training data solely on experiments. Herein, we sweep a large range of geometric, crystallographic, and shock conditions within molecular dynamics (MD) simulations and demonstrate the breadth of RMI character in Cu that can be captured from the atomic scale. Yield strength measurements from jetted and arrested material from a sinusoidal surface perturbation were quantified. These defect-free, single crystal Cu samples used in MD will overestimate strength, but the drastic scale difference between experiment and MD is highlighted by high confidence neighborhood clustering predictions of RMI characterizations yielding incorrect classifications. These results will be discussed in a broader context of multi-scale modeling where individual methods probe vastly different length and time scales.