Analysis and Simulation Verification of the Strain Transfer Model for the FBG Sensor With Surface-Bonded in the Nongrating Region

The surface-bonded fiber Bragg grating (FBG) sensors are extensively utilized in structural health monitoring. During the strain transfer process from the substrate being measured to the FBG sensor, shear deformation occurs within the adhesive layer. Consequently, the strain detected by the FBG sensor differs from that of the substrate, resulting in strain transfer loss. To solve this problem, a relatively simple strain transfer model for the FBG sensor with surface-bonded in the nongrating region was developed. The impact of various parameters on strain transfer efficiency was examined, and the influence laws of parameters, such as the adhesive layer’s elastic modulus, thickness, and length on transfer efficiency, were elucidated. The theoretical model was validated through finite element simulation. This model offers a theoretical foundation for the design optimization and precise calibration of FBG sensors, as well as for strain monitoring in applications, such as bridges and aerospace.