Crack Detection in Metallic Structures Using Broadband Excitation of Acousto-Ultrasonics

This paper reports the application of piezoceramic sensors for crack detection in metallic structures. Rectangular aluminium plates with a crack initiated by spark erosion were used in a simple fatigue experiment. The plates were instrumented with piezoceramic devices bonded in a symmetrical configuration on both sides of the crack. One of the piezoceramics was used as an actuator and excited by a sine sweep and Gaussian white noise signals in order to exploit broadband excitation. The plates were subjected to static and dynamic tensile loading. The growing crack was monitored by the remaining piezoceramic sensors. The experimental data were analyzed using time, frequency and wavelet domain statistical parameters. The results show the potential of the low-frequency broadband excitation for structure-integrated damage detection systems based on acousto-ultrasonics in metallics.