Durability of Structural Health Monitoring Systems under Impact Loading

This paper reports an experimental study on the degradation of Piezoelectric Wafer Active Sensors (PWAS) under impact loading. Carbon/epoxy laminates with surface bonded / embedded sensors were subjected to different levels of impact energy, and the performance of PWAS was monitored using impedance analysis. The effect of direct and indirect impact loading on the degradation of piezoelectric sensors was also examined. Using the force history data, a reduction in the flexural stiffness of the embedded specimens was identified. Examining the capacitance, output voltage and electromechanical impedance of PWAS, it was found that the degradation of the sensors under impact loading depends on the level of impact energy, location of the impactor as well as the number of impacts. Identification of the structural damage and sensor's degradation was verified using SEM micrographs.