Shielding effects of disclinations on the elliptical blunt crack

The influence of the disclinations is of great importance in deformation behavior and structure formation of strongly deformed materials. By introducing to the disclination approach in the description of defect structure development in strongly deformed materials, a theoretical model to study the elastic interaction between a wedge disclination dipole and the elliptical blunted crack is considered. Using the complex variable method, the complex potential and stress field have been derived near the tip of the elliptical blunt crack. From the stress fields, the stress intensity factors (SIFs) at the crack tip are obtained with the effect of a wedge disclination dipole. The influence of the morphology and blunting of the elliptical blunt crack, and the features of the disclination dipole on the SIFs at tip of the elliptical blunt crack is examined in detail. The results show that disclinations exhibit great influence on the mechanical field around elliptical blunted crack tips. Duo to the disclination shielding, the disclination dipole might induce to improve the toughness of crystalline materials. The shielding effect to SIF increases with increasing the crack length, the relative dipole arm and the rotation strength of disclination dipole, and the effect of the shielding effect to SIF is distinctly stronger with the increment of them. There exits critical crack blunting to make the maximum shielding effect to SIF. For both modes I and II blunt cracks, the shielding or anti-shielding effect to SIF becomes more pronounced with different location angles and rotational deformation orientations.