The range of applicability of the small-scale yielding approach in theoretical investigations of yield and fracture at a crack tip

Abstract

Theoretical analysis of the processes of plastic deformation and fracture in the vicinity of a sharp crack tip becomes easier if plasticity is confined to the immediate vicinity of the crack tip, for linear elastic stress intensity factors can be used to give the surrounding elastic field, and it is possible to employ a boundary layer formulation to determine the elastic-plastic field in the immediate vicinity of the crack tip. Consideration is given to the range of applicability of the small-scale yielding approach using a simple model in which slip is confined to the crack plane. A range of stress-displacement laws is considered, the object being to assess the effect of a material's flow characteristics on the range of applicability. The conclusions are discussed with respect to plane strain crack propagation in mild steel.