Interfacial debonding detection in bonded repair with a fiber optical interferometric sensor

To ensure the reliability and safety of structures repaired with bonded plate, the detection of interfacial debonding is an important part of any inspection process. In this article, a debonding detection technique based on fiber optic interferometry is proposed. A quasi-impulse loading is applied and the total elongation of a surface-mounted optical fiber along the length of the repair material is measured as a function of load position. When a debonding is present, the induced perturbations on the plot of fiber integral strain vs. load position will reveal the extent and location of the debonded area. With its simplicity, the technique is suitable for in situ damage detection while in service. To demonstrate the feasibility of the technique, experimental testing of bonded repairs with interfacial debonding has been carried out. To complement the test results, numerical analysis has also been performed. The results of the study indicate that the proposed technique is applicable for debonding detection in repaired members under various support conditions.