15 April 2011 Analysis of fiber Bragg grating spectral features for in-situ assessment of composites
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Embedded sensors provide a high sensitivity to sub-surface damage due to their proximity to the damage features. In particular, fiber Bragg gratings (FBG) are easily embedded into laminates with a minimum of perturbation to the surrounding material microstructure. This paper summarizes some recent advances derived from full-spectral interrogation of FBG sensors for structural health monitoring and damage identification in composites. In particular we will present signals from the FBG reflected spectra that have been correlated to stress concentrations near crack tips, curing conditions during processing of composite laminates and the progression of delamination due to multiple low-velocity impacts in woven composite laminates and foam-core sandwich composites. Recent advances in interrogation systems for these sensors will also be discussed which have permitted dynamic evaluation of these parameters. Finally, spectral distortion can lead to errors in the interpretation of strain values from the peak wavelength measurement when peak waveforms are assumed. This distortion is highly dependent upon the local microstructure surrounding the sensor and therefore cannot be compensated a-priori through a calibration factor. This article demonstrates that full-spectral interrogation can provide sensor specific error compensation for these measurements. These results demonstrate the richness of information that can be obtained from full-spectral interrogation of FBG sensors in a complex, multiple stress component environment.
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Kara Peters, Kara Peters, } "Analysis of fiber Bragg grating spectral features for in-situ assessment of composites", Proc. SPIE 7982, Smart Sensor Phenomena, Technology, Networks, and Systems 2011, 798209 (15 April 2011); doi: 10.1117/12.881149; https://doi.org/10.1117/12.881149

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