The spall damage of Al at ultra-high strain rates: A combination of MD simulation and mechanical modelling

Molecular dynamics (MD) and mechanical modelling simulations were used to investigate the dynamic fracture mechanism and damage evolution in single crystal aluminium subjected to shock loadings. MD simulations of shock induced spalling were performed to investigate the effect of strain rate. It is discovered that as the strain rate increases, the critical stress for damage activation, the rate of damage development, and the spall strength increase, whereas the width of the damage region decreases. The time evolution of the void volume fraction obtained from MD simulations was then used to determine the parameters of several theoretical models, including the nucleation-and-growth (NAG) model and Kanel’s model. Coupled with the theoretical models and verified parameters, the one-dimensional finite element method (1-D FEM) was used to perform mechanical modelings of spallation under shock loadings. The calculated results, including the time evolutions of stress, free surface velocity, and the density distribution of the damage region, agree with the MD data. We believe that this study could shed light on the studies of spall damage under conditions of ultra-high strain rates.