Numerical simulation and experiment for acoustic-optical fiber based detection of interfacial damage in FRP-retrofitted structures

To ensure the reliability and safety of fiber reinforced plastic (FRP)-retrofitted structures, the detection of interfacial debonding is an important part of any reinforce quality inspection process. The principle and methodology of an acoustic-optical fiber non-destructive evaluation (NDE) technique based on free vibration theory of a thin plate was proposed for the detection of interfacial damage in FRP-retrofitted structures. A focused sound beam generated from variable frequency loudspeaker source can be controlled to form a locally vibration field of the surface of FRP-retrofitted structures. Local vibration anomalies caused by interfacial damage in the structure can be measured by surface-mounted optical fiber interferometer, and thus, interfacial damage can be detected, mapped, and quantified. Based on the results from both numerical and experimental studies, the feasibility of interfacial damage detection in FRP-retrofitted structures with the proposed technique is demonstrated.