Plastic strip model of circular crack under cyclic loading with damage accumulation

A cylindrical solid containing a penny-shaped crack in its mid plane is subjected to a remote tensile stress field. In the plastic region near the crack border, damage due to continuous deterioration of the material accumulates, and may lead to crack instability and crack growth. A damage model relating the crack opening displacement in the plastic zone to the fraction of the cross-sectional area occupied by voids is used to describe the conditions necessary for the onset of crack instability, fatigue crack propagation by cyclic loading, and rates of crack growth for time-dependent environmental effects.