Abstract: Some common small crack test specimens are presented as well as the fracture mechanics parameters that have been used to characterize their behavior. A review of the most newly developed stress intensity factor equations for a semicircular surface crack located at the center of the notch root and a quarter circular corner crack in the SENT specimen is given. The expression rules for the small crack data and the experimental techniques are described in detail.

Key words: fatigue(material), small-crack, stress-intensity factor, crack growth plasticreplica method