Abstract
The present study has attempted to simulate the growth of a fish-eye crack in the very high cycle fatigue of a high strength steel SUJ2 by using 3D FEM. A half model of a round-bar type cantilever rotating bending fatigue test specimen was used in the present FEM simulation. A facet-like region around a non-metallic inclusion, which is often called ODA, or optically dark area, was considered as the incipient crack. The crack size increments along the periphery of the elliptic crack were calculated from the distribution of the stress intensity factor value around the crack and an empirical Paris law of fatigue crack growth behavior in SUJ2. The growth of the crack from the numbers of fatigue cycles N to N+ΔN was done by adding the crack increments during ΔN to the crack shape at N. The resultant final shape of the fish-eye crack showed a good agreement with that observed on the fracture surface of a real specimen.
