Atomistic modelling of contribution of dislocations to crack opening displacements

Dislocation emission from the crack tip in the b.c.c. lattice of α-iron under quasistatic loading in mode I is modelled by means of 2D (plane strain) molecular dynamic simulations, using two different interatomic potentials. The calculated crack opening displacements (COD) between the atoms are compared with the COD in continuum treatment. The stress conditions at dislocation emission and at microcrack initiation and ductility criteria are examined.