Energy Dissipation Metrics for Fatigue Damage Detection in the Short Crack Regime for Aluminum Alloys

In this paper, three distinct energy dissipation metrics are proposed to enable fatigue damage detection in aluminum specimens. The metrics are (i) Energy Dissipation Rate, (ii) Cumulative Energy Dissipation, and (iii) Material Stiffness. They are created by using the force and displacement signals obtained from the fatigue testing apparatus during the testing of Al7075-T6 specimens. The apparatus is also equipped with a confocal microscope which calibrates the fatigue damage detection at a crack thickness of 10 μm, thereby, enabling precise detection in the short crack regime. Using all the three metrics, optimal thresholds are computed using receiver operating characteristics and the average accuracy of damage detection in quantified. Accordingly, the three metrics show an accuracy of 84.06%, 100%, and 84.32%, respectively in detecting the cracked specimens.