Atomistic simulation and continuum modeling of the dynamic tensile fracture and damage evolution of solid single crystalline Al with He bubble

Abstract

The dynamic tensile fracture mechanism and damage evolution characteristics of solid single crystalline Al with He bubble are investigated by molecular dynamics (MD) simulations and continuum modeling. The physical mechanism leading to fracture is found to be dominated by He bubble growth, in wide ranges of strain rate and initial bubble volume fraction. The bubble growth process can be divided into three stages and the microscopic mechanism is related to the plastic deformation of surrounding metallic material predominated by dislocation growth and movement. It is further revealed that the evolution characteristics of He bubble are independent on strain rate or initial bubble volume fraction, but the growth rate increases significantly with increasing strain rate or decreasing bubble fraction. Additionally, the critical stress for bubble growth and dynamic tensile strength at the strain rates from 106 /s to 1010 /s are obtained, showing strain rate hardening effect. Finally, a continuum model based on the understanding derived from MD simulations is proposed to describe the damage evolution of the metal with He bubble, including the new strength softening effect induced by bubble growth. The dynamic tensile processes at the strain rates from 104 /s to 1010 /s are calculated by this model, and the obtained pressure and bubble evolutions and dynamic tensile strength are in good agreement with available MD results. We suppose that the present study sheds some light on the dynamic fracture of solid metals containing He bubble.