Effect of T-stress on Edge Dislocation Formation at a Crack Tip under Mode I Loading

We calculate the effect of the nonsingular stress acting parallel to a crack (the “Tstress”) on edge dislocation nucleation at a crack loaded in Mode I. We find that this leads to crack size effect – that is, for small cracks (of order 100 atomic spacings or less), the T stress causes the critical load for dislocation nucleation (expressed in terms of the applied stress intensity factor) to deviate from the classical T = 0 result. Specific results are discussed for the case of a finite crack subject to remote tension, where it is shown that the threshold for dislocation nucleation is reduced.