FIBER Bragg Grating (FBG) sensor for estimation of Crack Mouth Opening Displacement (CMOD) in concrete

Abstract

Crack mouth opening displacement (CMOD) is one of the important parameters for characterizing the fracture properties in concrete. Amongst various optical fiber senors, Fiber Bragg gratings are (FBG) being used for structural health monitoring in the recent times. Very few reports exist in literature for use of CMOD estimation using FBG sensors. We report here, the use of FBG based sensor for the estimation of CMOD in plain concrete beams prepared as per recommendations of Reunion Internationale des Laboratoires et Experts des Materiaux, Systems de Construction et Ouvrages (RILEM) and subjected to three point bend test in a digitally controlled Universal Testing Machine (UTM). The results are compared with Linear Variable Differential Transformer (LVDT) and a good agreement is found. The FBG sensor's resolution is better than LVDT beyond the peak stress.