“…8 For exploiting the advantage of AE, numerous studies have been performed to identify crack initiation and characterize the fatigue crack growth phenomenon of various metallic materials and structures. 1,6,13,37,41 Most of these studies typically investigated the qualitative relationship between the crack growth and the AE signals. By analyzing the crack growth behavior and AE characteristics, different damage states such as crack initiation, stable crack growth, rapid crack growth, and final fracture can be effectively identified.…”