Smart Composite Repairs using PZT Discs as Actuators/Sensors

Bonded composite patches are an attractive way to repair cracked or corroded airframe structures because of their several advantages compared to traditional riveted doublers. However, certification issues limit the application of this technology. We present here the development of a SHM system for detecting disbonds between the patch and the structure. This will provide important information concerning the damage state of the repair. PZT discs embedded between the patch and the metallic parent structure are used to excite and detect Lamb waves. Analytical study of the ultrasonic characteristics of both structure and actuator is essential to adjust the experimental setup. Processing of the experimental signals allows us to locate and evaluate the size of the damage.