AE Entropy for Detection of Fatigue Crack Initiation and Growth

In this paper we investigate whether the entropy of acoustic emissions (AE), can be used for determination of fatigue crack initiation and growth in AA7075-T6. The AE used for studying the damage evolution is acquired during fatigue testing of notched specimen under uniaxial cyclic load. The results show that the evolutions of the AE entropy estimated in the time domain correlates well with the evolution of the AE hit count rate. One advantage of using AE entropy is that information of both the amplitude and the compactness of AE signals is accounted for. We propose a new technique for detection and determination of fatigue crack initiation and growth, which could have a major contribution to the structural diagnosis and prognosis. We also conceptually discuss a possible connection between the thermodynamic and information entropic approach. This hypothesis may offer a novel approach to link fundamental physics of failure (PoF) with fatigue damage.