MECHANICS OF NUCLEATION AND GROWTH OF FATIGUE CRACKS

This paper presents a review of works of the last decade on the theory of fatigue fracture. This theory is based on the synthesis of fracture mechanics with the mechanics of accumulation of dispersed defects. We discuss the basic relations of the theory. These relations include the stability conditions for the system "cracked body-loading device," the damage accumulation equations, and the equations describing the change of conditions at the crack fronts. The nucleation and initial stage of the growth of the cracks are described in terms of the probabilistic micromechanical model. To describe damage on the macrolevel, a continuous model of cumulative damage is used. The potentials of this theory are illustrated by the cases of a shallow crack developing from a surface deflect, corrosion fatigue crack, and flat tensile crack of an arbitrary shape.