Verifying the Shape Estimation Performance of Individual Attachment Type FBG Bending Sensors According to Longitudinal Intervals

In this study, finite element analysis-based verification was employed to analyze efficient installation intervals for a series of longitudinally installed FBG (Fiber Bragg Grating) bending sensors for the structural health monitoring of railway rails. Three FBG sensors spaced apart by 120-degree angles from the center were arranged along a circular rod to make a single of individual attachment type FBG bending sensor module. Railway load conditions were simulated to analyze gravitational displacement. Analysis of the longitudinal intervals of 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm for the FBG bending sensors demonstrated a linear decrease in error when installation intervals decreased, where intervals were 20 mm or longer. In intervals shorter than 20 mm, average error converged to a specific value. Given the importance of setting cost efficient sensor intervals within the allowable margin of error, the findings of this study are expected to contribute to the efficient use of FBG sensors in the field of railway rail structural health monitoring.