A Mechanics-informed Method for Real-time Acoustic Emission Source Classification During Fatigue Loading of Composite Structures

This paper presents a new approach aiming to improve the classification method of Acoustic Emission activity with a material mechanics perspective and to provide the means for real-time classification. This mechanics-informed approach consists of using the instantaneous fatigue cycle phase as hit labels. Two different types of materials were tested under Tension-Tension fatigue loading at R=0.1. The main goal was to trigger matrix cracking as the dominant failure mechanism and measure the stiffness degradation. In order to validate the approach, the stiffness degradation was measured using Digital Image Correlation. From the fatigue cycle phase labelling of hits, at least two distinct clusters were observed: first, the hits occurring mainly in the loading phase of the fatigue cycle, whichs activity correlates with the rate of stiffness degradation in the test specimens; and second, the hits occurring in the lower part the unloading phase of the fatigue cycle.