Rapid guided wave inspection of complex stiffened composite structural components using non-contact air-coupled ultrasound

This article demonstrates a rapid, fully non-contact inspection technique for a full-scale complex composite structural component using air-coupled ultrasonic guided waves. The presence of different features such as stiffeners, stringers and geometric variations in skin-stiffened structures makes the received guided wave signal cumbersome and difficult to interpret. Experiments, supported by three-dimensional finite element models, are used to demonstrate the physics of guided wave interaction with complex features and defect configurations. B-scans are used to detect geometric variations in skin, and also disbonds in the skin-stiffener interface. Correlation between the numerically simulated and experimentally obtained B-scans is established. Different regions in the B-scan images could be used to locate and identify the defects and geometric variations in the test sample. The size of the disbond can also be computed from the B-scan.