광섬유 센서를 이용한 복합적층판의 모재균열검출

Abstract

An optical fiber sensor based on the Michelson interferometer was constructed to detect AE(acoustic emission) signal occurred by matrix cracking in the laminated composites. To validate an optical fiber sensor as AE transducer. a forced vibration test for a composite beam was performed. In the experiment. the frequency of the detected signal was compared to the excitation frequencies with the frequency range of AE by matrix crack. The survivability of optical fiber sensor was tested experimentally. The experiment showed that it was advantageous to embed an optical fiber in the direction of the reinforced fiber of the composite laminates to protect the optical fiber from matrix cracks of various types. Also. the effect of the embedded direction of the optical fiber on the sensitivity-of acquiring AE signal was examined. Under the tensile loading. the matrix cracking was detected by acquiring AE signal for cross-ply laminated composites. and it was confirmed by the replica method. As the density of matrix cracking was saturated. the detected signal waves showed relatively large energy release. In the frequency analysis of AE signal for matrix cracking. the characteristic frequency ranged approximately up to 120kHz.