ABSTRACT

In chapter 2 the elastic stress field equations for a sharp crack, equations (2.24), were obtained. These equations result in infinite stresses at the crack tip, i.e. there is a stress singularity. This solution is for a crack with zero crack tip radius. However, real materials have an atomic structure, and the minimum finite tip radius is about the interatomic distance. This limits the stresses at the crack tip. More importantly, structural materials deform plastically above the yield stress and so in reality there will be a plastic zone surrounding the crack tip.