Design and Investigation of a Fiber Bragg Grating Tilt Sensor With Vibration Damping

Fiber Bragg grating (FBG) sensors play an increasingly important role in structural health monitoring, and tilt sensors are one of the most commonly used among them. Traditional FBG tilt sensors are easily affected by external vibration, and to overcome such a problem, this work proposes a novel FBG tilt sensor with a vibration damping feature. Based on the classical equal strength beam structure, a vibration-isolating spring is used as the vibration-damping connection between the beam and the mass block, while a damping fluid is filled inside the sensor housing as the vibration-damping material. After elaborating on the details of sensor structural design and measurement theory, five sensors were set up for relevant performance tests, and the controlled experiments were carried out for the FBG sensors with and without the vibration isolation springs. Meanwhile, for sensors with vibration isolation springs, the viscosity of filled damping fluid was also varied in the experiments, to better reveal its influence on the sensor performance. The experimental results show that the proposed sensors have a high sensitivity of 112.743 pm/° within a range of ±15° and also have superior creep resistance as well as good temperature compensation capability. From controlled experiments, it is evident that the proposed sensor with a vibration damping structure offers better vibration stability and monitoring accuracy and can be effectively adapted to safety monitoring tasks in different engineering applications by simply adjusting the viscosity of filled damping fluid.