Multiple damage detection techniques by dynamic strain measurements using FBG sensors

The development of smart sensors for structural health monitoring and damage detection has been advanced remarkably in recent years. Nowadays fiber optic sensors, especially fiber Bragg grating (FBG) sensors, have attracted many researchers' interest for their attractive features, such as multiplexing capability, durability, lightweight and electromagnetic interference immunity. In this paper, two damage detection approaches by dynamic strain measurements using FBG sensors are presented. They are the modal strain-flexibility and the modal strain energy methods. An experimental study was conducted to investigate the feasibility of the methods for damage detection and localization. It has been found that the strain-based approaches using dynamic strain measurements from FBG sensors can successfully detect and localize multiple small damages near the sensors. However, the damage detection range of the present short-gage FBG sensors seems rather narrow. Long-gage FBG sensors would be a possible solution.