Issue 51

G.S. Serovaev et alii, Frattura ed Integrità Strutturale, 51 (2020) 225-235; DOI: 10.3221/IGF-ESIS.51.18 229 Figure 5 : GFRP specimen with embedded FBGs. Fiber-optic sensor readings from this specimen where analyzed after the manufacturing stage without any additional external forces applied. Bragg wavelengths of FBGs were spaced out in the range 1500 – 1600 nm to not interfere with each other and the general spectrum is presented in Fig. 6. Figure 6 : Reflected spectrum of 5 FBGs embedded in the GFRP specimen. During the manufacture of composite material, optical fiber didn’t lose its integrity and all FBGs are clearly distinguishable on the reflected spectrum. But a close analysis of reflected optical signal from each FBG, presented in Fig. 7, shows that the spectrum became highly distorted after the applied technological process. Figure 7 : Reflected spectra for each FBG embedded in GFRP specimen.