Real-Time Fatigue Crack Monitoring Based on Fiber Bragg Grating Sensors

In this paper, an real-time fatigue crack monitoring method is investigated based on the fiber Bragg grating (FBG) sensors. Three FBGs are applied along the direction of crack propagation to monitor a fatigue crack with size of 10mm. Experimental results demonstrate that the reflection spectrum changes observably with the propagation of crack when the crack is within 3-4mm long of each FBG. Characteristic parameters are constructed to detect the variation degree of reflection spectrum. A crack quantification model based on characteristic parameters is proposed to describe the correlation between the crack size and damage sensitive features extracted form FBG measurements. It makes possible to monitor the propagation of crack quantitatively within 3-4 mm long for each FBG. Finally, a certain size crack can be monitored using several FBGs.