R&D Of FBG Strain Sensors

Recently, with the rapid development of fiber sensing technology and the increasing need for structure health monitoring in civil engineering, FBG sensors are showing their more and more prominent advantages in civil engineering than traditional mechanical and electrical sensors. Strain is an important index for project structure safety and it is meaningful to study novel FBG-based strain sensors to take long-time, real-time and dynamic monitor for the strain of structure in civil engineering.In this paper, three new kinds of FBG-based strain sensors with marvelous sensing performance have been developed, and the trials are carried out. The main work and results are as follows:Firstly, two novel sensitivity-enhanced and long-scale FBG-based strain sensors are designed according to the simple principle: sections with different shapes result in different strains distribution. With this great property we can change the sensitivity steadily and reliably by setting FBG on the proper position.Secondly, in view of the need for strain-in monitoring of concrete and sensors'durability and maneuverability, we will encapsulate the FBG into the FRP and thus we can get the excellent FRP-OFBG sensing pole. Then the embedded FRP strain sensors with fixtures at two ends will be designed and manufactured. The trials about the sensors are carried out.Finally, in view of the need for strain monitoring of steel surface, and sensors'durability and maneuverability, we also use FRP-OFBG sensing pole to design and manufacture the surface-welded FRP strain sensors. The trials about the sensors are carried out.FBG-based strain sensor has many virtues such as unerodibility, absolute code of wavelength, ability for anti-jamming, simple structure and easy execution, etc. So it can replace the traditional mechanical and electrical strain sensor in civil engineering, and has prosperous outlook in the application.