Effect of T-stress on the cleavage crack growth resistance resulting from plastic flow

Crack growth is studied numerically for cases where fracture occurs by atom ic separation, sc that the length scale of the fracture process is typicall y much smaller than the dislocation spacing. Thus, the crack growth mechani sm is brittle, but due to plastic flow at some distance from the crack tip, the materials show crack growth resistance. It is shown here that the resi stance is strongly dependent on the value of the non-singular T-stress, act ing parallel to the crack plane. The numerical technique employed makes use of a thin dislocation-free strip of elastic material inside which the crac k propagates, with the material outside described by continuum plasticity. Thus the width of the strip is a material length scale comparable to the di slocation spacing or the dislocation cell size.