Interface transferring mechanism and error modification of embedded FBG strain sensor based on creep part I: Linear viscoelasticity

As strain-sensing elements in the structural health monitoring, the research and application of the Fiber-optic Bragg Grating sensor (FBG) has been widely accepted. Although there are some significant achievements on the interface transferring mechanism and error modification of FBG, the theoretical research on the creep behavior of FBG sensors is rarely taken into account. Because the optical fiber and adhesive is macromolecular polymer, when loaded in long term or high temperature, the creep characteristic of these material is emerging which influences the accuracy of FBG sensors. This paper presents the theoretical part on creep behavior of FBG sensors. Firstly, based on the linear viscoelastic constitutive relations, the general expression of multiplayer interface strain transferring mechanism is derived, and the error modified equation of FBG sensors is obtained. Secondly, the transient and steady-state responses of FBG sensors are presented. Finally, the elasticity-viscoelasticity corresponding principle is proposed, which is used for solving a class of interface strain transferring linear viscoelastic problem.