Damage and failure monitoring of fiber-metal laminates using optical fiber sensors

Abstract

Optical fiber vibrations sensors(OFVS) and extrinsic Fabry-Perot interferometer(EFPI) were used in damage monitoring of fiber-metal laminates(FML). The OFVS and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Indentation tests were performed with the measurement of optical signal and acoustic emission(A-E). Robust signal processing methods based on time-frequency analysis were proposed to monitor damage signals of the structure with removing the influence of environmental and sensor noise. The signals of the OFVS due to damages were quantitatively evaluated by wavelet transform(WT). Relative position and condition between the specimen and indenter were able to estimate by observing the fiber-optic interference fringes of EFPI. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the OFVS signals. The OFVS proved to be effective for monitoring the damage process of the material studied here.