Introduction: Structural health monitoring (SHM) in aeronautical components is challenged by the high cost, downtime, and limited real-time capability of conventional inspection methods such as ultrasonic testing or Eddy current evaluation. To address these limitations, this work proposes an innovative and scalable strain-based monitoring approach for crack propagation in aircraft-grade aluminum structures.

Methods: Aluminum 6082-T6 fuselage-representative specimens were experimentally tested under both static tensile loading and fatigue cycling. Samples included unnotched, notched, and pre-cracked configurations to replicate stress concentration effects typical of riveted aircraft panels. A network of six strategically positioned strain gauges was implemented to capture localized strain evolution during crack growth under cyclic loads of 3, 3.5, and 4 kN. Crack length estimations from strain signals were validated through periodic Eddy current inspections. Based on linear fracture mechanics principles, a novel mathematical formulation was developed to directly correlate strain ratios with crack length without requiring full load knowledge.

Results: The proposed predictive model demonstrated high reliability, achieving correlation coefficients above 0.97 between estimated and measured crack lengths across fatigue conditions. The method provided an average absolute error of 2.23 mm, enabling continuous crack sizing throughout propagation. Higher load levels significantly reduced fatigue life, confirming accelerated crack kinetics under increased stress amplitudes.

Conclusions: This study introduces a cost-effective, real-time SHM methodology integrating conventional strain gauge networks with predictive fracture modeling. The approach offers strong potential for deployment in critical fuselage regions between rivets, minimizing aircraft maintenance interruptions while enhancing operational safety and efficiency.