The far-field eddy current detection of inner layer crack of aviation multilayer riveted structures

The multilayer riveted structure is the main structure of aircraft fuselage skin and profiles. Due to periodic loading, fatigue cracks are prone to occur in load-bearing parts such as internal profiles, which are highly concealed and difficult to detect using visual and conventional nondestructive testing techniques. The far-field eddy current detection technology can detect defects with a large burial depth, so it was applied to the inner layer crack detection of aircraft multilayer riveted structures. The results indicated that the amplitude of the detection signal impedance had a good linear relationship with the crack depth, and the phase angle of the detection signal impedance had a good linear relationship with the crack burial depth by selecting an appropriate detection frequency. For the determined tested material and detection sensor, the fitting formula obtained can provide a theoretical reference for the localization and quantitative detection of crack damage, thus obtaining accurate information of cracks and achieving accurate localization and quantitative detection of crack damage.