A multiscale strength model for extreme loading conditions

We present a multiscale strength model in which strength depends on pressure, strain rate, temperature, and evolving dislocation density. Model construction employs an information passing paradigm to span from the atomistic level to the continuum level. Simulation methods in the overall hierarchy include density functional theory, molecular statics, molecular dynamics, dislocation dynamics, and continuum based approaches. Given the nature of the subcontinuum simulations upon which the strength model is based, the model is particularly appropriate to strain rates in excess of 10(4) s(-1). Strength model parameters are obtained entirely from the hierarchy of simulation methods to obtain a full strength model in a range of loading conditions that so far has been inaccessible to direct measurement of material strength. Model predictions compare favorably with relevant high energy density physics (HEDP) experiments that have bearing on material strength. The model is used to provide insight into HEDP experimental observations and to make predictions of what might be observable using dynamic x-ray diffraction based experimental methods. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3553718]