Emission of a half-rectangular dislocation loop from a mode I crack tip

Energies for emission of a half-rectangular dislocation loop from a mode I crack tip are investigated in the present work. Optimum aspect ratio of length to width of the half-rectangular loop, critical dislocation size, and activation energy for dislocation emission are calculated by determining the saddle point of the total energy profile as a function of the length and the width. The activation energy obtained for the half-rectangular loop is less than a quarter of that obtained for a semicircular loop. The effects of the self-energy correction parameter and the radius of the dislocation core on the activation energy are also reported here.