抄録
An ultrasonic sensing system using fiber Bragg gratings (FBGs) was constructed. The system utilizes wavelength-optical intensity modulation technique and includes a broadband light source, FBGs for sensing and filtering, as well as a photodetector. Feasibility of active sensing by the system was examined. Ultrasonic Lamb wave generated by an ultrasonic transducer was propagated in a cross-ply CFRP with impact damage. Response of FBG sensor to Lamb wave propagated through a damaged area was compared with the reference response in an intact area. In this experiment, the ultrasonic transducer was driven by four kinds of signals to determine the optimal transducer drive signal for impact damage detection. Response to Lamb wave propagated through the damaged area had narrower frequency bandwidth and lower frequency characteristics than response in the intact area. A spike pulse proved to be optimal for the transducer drive signal in active sensing. The experiments demonstrated that the FBG ultrasonic sensing system was effective to detect impact damage of CFRP.
