Material Characterization of a Flat Plate with Shock Impingement: from Continuum to Atomistic Scale

Although various studies on shock impingement have been carried out focusing on the fluid dynamic characterization of the shock and the boundary layer properties, effects on the material characterization of the associated structures have largely been ignored. This work investigates the mechanical and structural stability of an aluminum surface with regards to a discontinuity in the surface traction across an idealized shock, using Stroh’s formalism and molecular dynamics, respectively. Stroh’s method is used to evaluate the normalized von Mises stress fields, near the shock using dual coordinates, caused by discontinuous surface traction with different orientations. A pure shear stress jump causes a stress singularity locating at the discontinuity point in the stress field and is observed to generally produce higher stress values within the region of interest than a pure pressure jump. Moreover, the region associated with relatively high stress values gradually shrinks as the surface traction transitions from pure shear stresses to pure pressures. Finally, we evaluate a test case of Mach 2 shock interaction performing both Stroh’s method and molecular dynamics simulations. It is illustrated that the singularity in the calculated von Mises stress fields, is extremely localized, so that it can most likely be treated as negligible. Compared to the yield strength, the resulting von Mises stress is much lower and the MD results also match structural features of aluminum crystal, which indicates that the aluminum structure remains mechanically and structurally stable under a Mach 2 shock.