Guided wave imaging of part-thickness defects in large structures

Distributed guided ultrasonic wave array systems allow for the efficient structural health monitoring (SHM) of large structures, such as aircraft or ship hulls. Permanently attached sensor arrays have been applied for the detection and imaging of corrosion and fatigue damage. A hybrid model has been developed for the efficient prediction of the sensitivity of guided wave array systems to detect through thickness and part-through fatigue cracks in plate structures. The influence of the orientation of the crack relative to the transducer elements had been predicted from localized 3D Finite Element simulations and verified experimentally. Using the hybrid model, detection and imaging capabilities can be predicted for various defect depths, and the sensor layout and signal processing optimized. This has been demonstrated from laboratory experiments. Part-thickness notches and holes of increasing depth were machined into an aluminum plate and imaged using distributed sensors for the A0 Lamb wave mode. Based on...