Strain Transfer of Bonded FBG Sensor for Coal Mining Similar Model

Abstract

To accurately monitor the strain of a host with low strength, a new strain transfer model is proposed for the substrate FBG sensor. In the strain transfer model, the mechanical properties of the host are taken into consideration. The strain relationship between the fiber core and the host is obtained. The theoretical approach was verified by numerical simulation and experimental results. The influences of the mechanical parameters of the host on the strain transfer are analyzed. It is concluded that the strain transfer rate increases nonlinearly with the increase of the shear modulus of the host. The shear modulus of the host has different influence in different strain ranges; for the low strength host, the mechanical parameters of the host have great influence on the strain transfer rate. These results provide theoretical guidelines for the FBG sensor applications in low strength host. This study proposes an improved strain transfer model of the substrate FBG which is suitable for a coal mining model. From the proposed model, a theoretical formula is derived and used to predict the strain transfer relationship between the coal mining model and the fiber core in consideration of the mechanical properties of the host. Then, a numerical simulation by FEM and practical experiments are conducted to validate the theoretical predictions.