A Temperature-Insensitive FBG Acceleration Sensor with Sinusoid-Shaped Curved Beams

It is an important means to identify and evaluate the structural damage of buildings before and after earthquake disaster by using fiber Bragg grating acceleration sensor to obtain the natural frequency of building structure. In order to solve the problem of temperature cross sensitivity of fiber Bragg grating (FBG) in structural health monitoring, a novel acceleration sensor based on strain chirp effect which is insensitive to temperature is proposed. A kind of M-shaped double cantilever beam structure is developed. The fiber grating is pasted in the gradient strain region of the beam, and the chirp effect is produced under the action of non-uniform stress, and then the change of acceleration is converted into the change of reflection bandwidth to demodulate and eliminate the temperature interference. Through theoretical analysis, simulation and experimental verification with rectangular beam sensor. The results show that the sinusoidal curvature beam sensor is insensitive to the change of temperature and is more likely to produce chirp effect. The sensitivity is about 317 pm/g, and the natural frequency is 56 Hz.