抄録
A small crack shows anonalous growth behavior in comparison with a large crack. In both large and small cracks, however, the fundamental factor controlling the crack growth rate is the cyclic displacement near the crack tip. In the present review, two fatigue crack growth laws in small and large cracks, dl/dN∝σnal and dl/dN∝ΔKm, which formally contradict each other unless m=n=2, were explained consistently using the assumption dl/dN ∝rprev. Moreover, the validity and the limitation for application of the small-crack growth law were explained by experimental results and the practical prediction method for fatigue life was suggested.
