A COMPUTER SIMULATION OF THE CRACK PROPAGATION PROCESS

The crack propagation process is studied by Monte-Carlo simulation for a two-dimensional triangular lattice with the Lennard-Jones potential and a surface notch. Nucleation of dislocations at the crack tip and their propagation past the crack tip region are found to precede the crack growth in the present case, this result is in close agreement with that of the molecular dynamics simulation by Halicioglu and Cooper [Mar. Sci. Eng., 79, 157 (1986)]. To represent the state of the local domain around the crack tip which is characteristic of the onset of dislocation nucleation or that of crack extension, we employ the stiffness coefficients in connection with each atom. It is found that the magnitude of the relevant stiffness coefficient diminishes as each of those processes is about to occur.