Numerical and Experimental Comparison of Impact Damage Detection by Using Piezoceramic Sensors/Actuators on a Stiffened Composite Panel

Abstract

This work proposes a Structural Health Monitoring system for the detection and measurement of delamination areas in composite stiffened wing panels generated by low energy impacts, by using a network of sensors/actuators piezoceramics (PZT). This system is an offline system, pointing to be an alternative method to the current NDI/C-scan techniques. The activities were performed in SMAF (SMart AirFrame) project of PRORA (the Italian Aerospace Research Program) and its promising reliability in the detection and measurement of the impact damage area was demonstrated. The SHM algorithm is based on the elliptical triangulation method and high frequency Lamb waves. The network of PZT, placed on a composite stiffened panel, excites the structure with ultrasonic waves and, at the same moment, measures the perturbations induced by discontinuities present within the panel, like delamination. Through the calculation of the Time of Flight (ToF) of the signals and the knowledge of the actuator-sensor position, the method identifies location and dimension of the damage. Many low energy impacts were performed on a full-scale stiffened panel and BVID (Barely Visible Impact Damage) was obtained in different positions. The SHM-PZT system was applied to identify both the position and severity of the damage. The results were compared with the C-scan measurements and a good agreement was achieved.