A theoretical strain transfer model between optical fiber sensors and monitored substrates

Abstract

This study proposed an analytical model to investigate strain transfer mechanism between FBG sensor and measured geogrid. Both geometric and mechanical parameters (bonding length, bonding thickness, bonding width, and Young's modulus) of interaction interface can be taken into account in this model. Both laboratory tensile tests of geogrid and experimental data in published literatures were used to verify the developed model. Validation study shows that the maximum relative error between experimental values and theoretical values is 8.2%, indicating that this theoretical model can be used to reflect geogrid deformation. Parametric study indicates that bonding length, bonding thickness, bonding width, Young's modulus of adhesive layer, and substrate layer have significant influence on strain transfer coefficient. Grey Relational Analysis (GRA) method was used to analyze influencing sensitivity of different parameters. GRA parameter values of bonding width and length are higher than 0.72, indicating that bonding width and bonding length are relatively dominant factors affecting average strain transfer coefficient in comparison with bonding thickness, Young's moduli of substrate and adhesive layers (their related GRA values are all lower than 0.692).