Spall and recompression processes with double shock loading of polycrystalline copper

Abstract

Spall fracture induced by interaction of multiple shockwaves in shock-loaded material is a key issue for both basic science and practical application. Here, shock induced spall and subsequent recompression process of polycrystalline copper are investigated using molecular dynamics simulations. Two significant velocity peaks are observed from the velocity history of free surface, which is explained through the complex propagation of waves and dynamic damage processes. The overshoot feature is also noted in the free-surface velocities on account of the shock response of the damaged region. Recrystallization occurs after secondary shock passes through the spall region. Meanwhile, the differences in recrystallization processes are observed for the different shock response states of the spall region induced by secondary shock waves. What's more, the reduction of grain sizes in the spall region is also revealed in our simulation, which is consistent with experiments.