Embedded fiber Bragg sensors for damage identification in sandwich composites after impact

摘要

The use and viability of fiber Bragg grating sensors in sandwich composite structures for the purpose of structural health monitoring under low velocity impact. Initially, a group of twelve specimens were tested to characterize the impact response of sandwich composite structures. Each specimen test consisted of repeated impacts at a constant impact energy to measure and observe damage progression. Once this was completed, a single optical fiber with a fiber Bragg grating was embedded in the structure between the core and the faceplate to and measured using a laser. The shift and deformation of the reflected spectrum from the fiber Bragg grating sensor resulting from each strike was analyzed and the corresponding strain was measured. The peak wavelength shift measurements did not have a strong correlation to the accumulation of damage in the sandwich laminate. However, the spectral distortion did evolve throughout the initial accumulation of damage in the laminate. Further analysis of the spectrum is needed to correlate the spectral response to the damage modes.