Degradation of Sensor Systems in Multifunctional Composites

Structural health monitoring (SHM) systems are increasingly being considered for implementation in aerospace structures. As the application of SHM systems increase, it will be important to define standardized procedures to test durability, reliability, and longevity of the systems. The work presented in this paper is some preliminary work on the integrity of Piezoelectric sensors itself when used to monitor the strains in structures. This study involved the measurements of pertinent electrical properties of these sensors over 100,000 cycles of fatigue loading. Marked changes in the capacitance and inductance of these sensors highlighted deleterious structural changes in the sensor itself without any discernible change in the structure it is supposed to monitor. This might have significant implications in the reliability assessment of sensory data from SHM systems.