Challenges to model the role of heterogeneities on the shock response and spall failure of metallic materials at the mesoscales

The predictive modeling of the experimentally observed behavior of metallic materials under shock loading conditions (wave structures, spall strengths) is a critical challenge toward the design of next-generation structural materials. This challenge is due to the lack of computational methods that can predict microstructural evolution at the mesoscales under dynamic loading conditions. While classical molecular dynamics simulations have been able to provide atomic-scale insights in the defect and damage nucleation/evolution mechanisms, the capability to have a direct comparison with experimental data at the same time and length scales is still a challenge. The current computational approaches require that several approximations be made either for the loading conditions or for the micromechanisms related to defect evolution and interaction at the mesoscales. This viewpoint discusses the insights obtained from molecular dynamics simulations of shock deformation and spall failure of heterogeneous metallic microstructures. An example Al–Ni microstructure is used to identify the critical atomic-scale phenomena that need to be addressed by the mesoscale methods when considering shock deformation and failure (spallation) at the mesoscales.