Damage Detection for Composite Laminate Plates with A Distributed Hybrid PZT/FBG Sensor Network

Abstract

Debond detection is a critical technique to ensure composite structural safety. Although there are many novel sensors being developed in recent years, piezoelectric transducers (PZT) and fiber Bragg grating (FBG) sensors have been shown as ideal sensors for monitoring structural health. To utilize their merits and overcome their drawbacks a hybrid PZT/FBG system has been developed to detect damage in composite laminate plates. The hybrid diagnostic system combines piezoelectric actuators which input a controlled excitation to the structure and fiber optic sensors which capture the corresponding structural response. Tests have been carried out to demonstrate the feasibility of detecting simulated damage monitoring on an aluminum plate and debond damage on composite plates using the suggested hybrid system. Test results show that the system is capable of detecting damage in both aluminum and composite plates. The major advantage of this system lies in actuator/ sensor decoupling, because they use different mechanisms for signal transmission. It may also offer long distance signal transmission because it utilizes fiber optics to transfer sensor signals to its interrogation system. The potential to sense acoustic stress waves and absolute quasi-static strains with large amount of sensors engraved along a single optical fiber may also increase the practibility of using a PZT/FBG hybrid system.