We have developed a novel damage monitoring system that can monitor the integrity of composite structures in aircrafts.
In this system, fiber Bragg grating (FBG) sensors are used as sensors and piezoelectric transducers (PZT) are used as the
generators of elastic waves that propagate in the structure to be inspected. The damage monitoring system can detect the
structural integrity by the change in elastic waves that are detected by the FBG sensor and arrayed waveguide grating
(AWG)-type filter. We confirmed that the structure health monitoring (SHM) system was able to monitor the damage
initiation and propagation by a change in the waveform of the elastic waves in coupon specimens and structural element
specimens. In this study, we demonstrate the detectability of the damage monitoring system by using a subcomponent
test specimen that simulates an actual aircraft wing box structure composed of carbon fiber reinforced plastics (CFRPs).
The FBG sensors and PZTs are bonded to the surfaces of hat-shaped stringers by an adhesive. Damages such as de-bonding
and delamination are introduced in the bonded sections of the skin and stringers by impact. Damage monitoring
and diagnosis are carried out by the SHM system under ambient conditions. We successfully verify the detectability of