A new method for eddy current testing of crack length in aircraft load-bearing components based on resonance method

Aircraft bearing beams are critical structures securing landing gear, yet prone to fracture during service. Detecting hidden defects beneath composite layers remains challenging. To address this, a novel eddy current sensor was designed and developed with high sensitivity and the ability to detect hidden cracks in the large lift-off state. A novel three-dimensional model has been proposed for detecting defects in aircraft load-bearing components under the application of composite materials. The model utilizes the calculation and matching of coil impedance of the large lift-off eddy current scattering field, and analyzes eddy current diffusion at defect endpoints under composite layers. Simulations and experiments demonstrate the coil resonant probe outperforms non-resonant counterparts, and the optimized probe can detecting defects as small as 5 mm (length) × 0.2 mm (width) × 0.5 mm (depth) . Eddy current penetration increases with sector defect radius until stabilizing beyond a threshold radius. The novelty lies in the resonance-enhanced impedance matching method, which significantly improves sensitivity for detecting sub-composite cracks under large lift-off (3 mm). .