Stress distribution and effective stress intensity factor of a blunt crackafter dislocation emission

The stress fields induced by a dislocation and its image dislocations aroun d a narrow elliptic void are formulated. Based on the solution, the stress distribution and effective stress intensity factor of a blunt (elliptic) cr ack were calculated under mode I constant loading. The results show that a dislocation-free zone (DFZ) is formed after dislocation emission. There exi sts a second stress peak in the DFZ except a stress peak at the blunt crack tip. With an increase in the applied stress intensity factor K-la or the f riction stress T-f of the material, the DFZ size and the peak stress at the crack tip decrease, but the peak stress in the DFZ and the effective stres s intensity factor K-lf, presiding at the crack tip increase. Because of di slocation shielding effects, shielding ratio K-la/K-lf increases with incre asing K-la, but it decreases with increasing T-f.