THE DISLOCATION-FREE ZONE AT A MODE-I CRACK-TIP

The distribution of dislocations in the vicinity of a mode I crack tip is formulated based on the observation of a single crystal specimen o f aluminium by transmission electron microscopy (TEM). Closed form exp ressions of the dislocation density function and the dislocation-free zone (DFZ) condition for a mode I crack are derived. The relationship between the size of the crack, dislocation-free zone and plastic zone is obtained as a function of the applied stress. The characteristic of this model is compared with that of the model proposed by Chang and O hr for a mode III crack.