Arbitrary strain distribution measurement using a genetic algorithm approach and two fiber Bragg grating intensity spectra

This paper proposes and verifies a simple, convenient, and low cost method to inversely measure arbitrary strain distributions by applying a genetic algorithm approach to analyze the reflection intensity spectra of two fiber Bragg gratings (FBGs). The proposed method involves bonding one uniform FBG and one chirped FBG to the same location of the structure of interest such that they both encounter the same strain field. The arbitrary strain distribution within the fiber gratings is then determined inversely from the two Bragg intensity spectra by means of a genetic algorithm population-based optimization process. The proposed measurement method is suitable for many smart structure-monitoring applications. (C) 2004 Elsevier B.V. All rights reserved.