Strain distribution and sensitivity in fiber Bragg grating sensors

Abstract

Optical Fiber Bragg Gratings (FBG) sensors have seen significant development in recent years. Such sensor technology developed initially for the civil infrastructure is currently attracting the aerospace industry due to the potential versatility of this technology and its measurement capability. The structural health monitoring and the diagnostics and prognostics health management communities are excited about such development and ready to embrace such capability. Sensors reliability and accuracy, however, continue to be two parameters critical to the eventual implementation of the technology in high value targets. Such parameters can be improved by different manufacturing techniques as well as optimum grating's coating selection. This paper presents an evaluation of the mechanical behavior of the FBG strain sensors. A simulated analysis, using finite element modeling, revealed the impact of coating material selection, coating thickness selection, and bonding effect on the strain transfer loss. Results illustrate that metallic fiber coatings are more suitable for improved strain transfer than their polymeric counterparts and acrylic coatings are least effective with adhesive layer as small as possible.