Characterization and Modeling of Bonded Piezoelectric Sensor Performance and Durability in Simulated Aircraft Environments (preprint)

A key question which needs to be addressed and answered with regard to successfully implementing structural health monitoring technologies involves the long-term operability, durability, and survivability of integrated sensor systems and their associated hardware. This is particularly true for structural health monitoring in aerospace systems, where integrated sensors are expected to perform and function effectively for many years under widely varying environmental conditions. In this research effort, the performance characteristics of surface-bonded piezoelectric sensors were studied under accelerated exposure conditions typically found in operational aircraft environments. Evidence of both gradual and abrupt sensor performance degradation was experimentally observed due to undesired load transfer processes between the substrate material and the sensor, which resulted in sensor disbond and cracking events. Models were developed to better understand the critical shear-strain and viscoelastic conditions present in a typical surface-bonded sensor system, which permitted key material parameters related to bond and piezoelectric material type to be identified. It is hoped that the results will help in making improved bonded sensor system design choices based on the long-term exposure conditions expected in typical aircraft flight environments.