Effect of special rotational deformation on dislocation emission from a semielliptical blunt crack tip in nanocrystalline solids

摘要

The paper established a model to investigate the interaction between the special rotational deformation and a semielliptical blunt crack in deformed nanocrystalline materials. By using the complex variable method, the effect of a disclination quadrupole produced by the special rotational deformation on the emission of lattice dislocation from a semielliptical blunt crack tip was explored theoretically. The complex form expression of the dislocation force was derived, and the critical stress intensity factors (SIFs) for the first edge dislocation emission were calculated. Then, the influence of the disclination strength, the disclination location and orientation, the special rotational deformation orientation, the grain size, and the curvature radius of blunt crack tip on the critical SIFs were discussed in detail, and a comparison with the sharp crack behavior was presented. The results show that the special rotational deformation and the curvature radius of blunt crack have great effects on the lattice dislocation emission form blunt crack tip. Some influence laws are also different with those of the edge dislocation emission from a sharp crack tip.