A series of atomistic simulation studies of dislocation emission and cleavage at crack tips in a model two dimensional hexagonal lattice is performed using the lattice Green's function method. Both bulk materials and interfaces are treated. The results are strongly dependent on the direction of emission. For Mode II emission (parallel to the crack plane), emission in both bulk and interface systems is well described by the shearing energy at the crack tip. For Mode I emission, in which new surface is created with the emerging dislocation, the shearing energy is insufficient, and a contribution from the surface energy must be included. We find that the observed emission stress-intensities are strongly correlated with the surface energy, if it is not too small. We also examine several interface-specific effects. Unphysical displacement oscillations which are found in continuum-elastic analyses are eliminated by shear breakdown of the bonds at the crack tip.
|Number of pages
|American Society of Mechanical Engineers, Applied Mechanics Division, AMD
|Published - 1995
|Proceedings of the 1995 Joint ASME Applied Mechanics and Materials Summer Meeting - Los Angeles, CA, USA
Duration: Jun 28 1995 → Jun 30 1995