Characterization of Fatigue Damage in Adhesively Bonded Lap Joints Through Dynamic, Full-Spectral Interrogation of Fiber Bragg Grating Sensors

摘要

In this work we demonstrate that dynamic, full-spectral scanning of FBG sensorsembedded in the adhesive bond can identify changes in bond quality through themeasurement of non-linear dynamics of the joint. The lap joint specimens were thensubjected to fatigue loading, with regular interrogation of the FBG sensors at selectedload cycle intervals. The FBG data was collected during vibration loading of the lapjoint to represent an in-flight environment. Changes in the lap joint dynamic response,including the transition to non-linear responses, were measured from both the fullspectraland peak wavelength FBG data. These changes were correlated to initialmanufacturing defects and the progression of fatigue-induced damage independentlymeasured with pulse phase imaging and visual inspections of the failure surfaces.Finite element simulation of the lap joint dynamic response verified that the FBGresponse was due to the fatigue-induced damage.