Fracture mechanics-based fatigue life prediction and structural health monitoring of piezoelectric thin films in aerospace structures under cyclic loading

The study focuses on the use of piezoelectric thin films for fatigue damage detection, crack growth monitoring, and intelligent structural health monitoring of aerospace components. Three materials PZT, Aluminum Nitride (AlN), Zinc Oxide (ZnO) were selected for this study on the basis of the sensitivity, adhesion, and surface quality of the material. PZT had the highest score in the three categories and was chosen for further investigation. RF magnetron sputtering was used to deposit PZT thin films onto aerospace grade AL7075 and CFRP substrates; the films were characterized by SEM, XRD and AFM analysis. The cyclic fatigue test yielded a gradual decrease in the response index from 10 × 10³ to 60 × 10³ load cycles, pointing to a progressive degradation in material properties. Crack growth was determined using fracture mechanics analysis (0.10 mm to 0.84 mm) and the maximum stress index was predicted using finite element simulations (2.1 to 8.9). The output voltage of the electromechanical analysis was linear in range of 0.60–2.65 V. The proposed monitoring framework has proved to be accurate for aerospace durability assessment and predictive maintenance, with error in fatigue life around 4% and accuracy of 92–98%.