Multiscale simulations of mixed-mode fracture in bcc-Fe

Mixed-mode fracture of bcc-Fe has been investigated using the quasicontinuum method with an embedded atom method potential. A modified boundary layer approach has been employed to simulate a semi-infinite crack and to investigate the influence of the degree of mode II and mode III loading on the crack tip mechanisms. The analyses have been carried out with four crystallographic orientations and different degrees of mixed-mode loading. The results show that the critical stress intensity factor and the mechanisms at the crack tip are sensitive to both the crystallographic orientation and the mode of loading. Phenomena such as crack propagation, twinning and emission of edge and screw dislocations are observed.