The Impact of Effective Refractive Index on Fibre Bragg Grating Sensor Sensitivity for Structural Health Monitoring

This research presents the impact of effective refractive index on Fibre Bragg Grating (FBG) sensor sensitivity for Structural Health Monitoring (SHM). SHM has been largely used in telecommunication, civil infrastructures, sports equipment, automotive, aerospace, oil and gas, and medical facilities due to their unique capability to monitor structures in a hazardous environment . In this research, the FBG sensitivity to induced strain on the composite structure was obtained at different effective refractive index values. T he shifts in Bragg wavelength was plotted against the induced strain on the composite structure at effective refractive index values of n eff1 = 1, n eff2 = 1.44, n eff3 = 1.5 and n eff4 = 2 at Poisson’s ratios ( ) of 0.3 and 0.19525 . The simulation was carried out in MATLAB R2018a version which shows the FBG with the lowest effective refractive index result in the highest sensitivity. The result of the FBG with n eff2 was compared with that of n eff3 . The result shows that a 1.49% increment in sensitivity was obtained at Poisson’s ratio ( ) of 0.3 and a 2.0% increment insensitivity was also achieved by the sensor when Poisson’s ratio ( ) is 0.19525 . The increment in the sensor’s sensitivity enabled the FBG sensor to be suitable for monitoring structures in harsh environment.