Residual strain measurement in bonded composite repairs for aging aircraft by embedded fiber Bragg grating sensors

Embedded Fiber-Bragg-Grating sensors are used for tracking the initiation of structural bonding and measuring the residual strains, during the curing process, of bonded composite patches used for aging aircraft structural repairs. FBG reading are shown to have direct correlation with the residual strains that are important in assessing the long-term durability of the repaired structure under fatigue load spectrum.