Abstract
Due to the error between the strain measured by the fiber grating sensor pasted on the surface of the substrate and the real strain of the substrate, the analysis of the relationship between the strain measured by the fiber and the actual strain of the substrate is the focus of this research. Since structures are subjected to various harsh conditions in actual service, such as temperature changes, fatigue, corrosion, aging, cracks and other external factors, when using surface-adhesive fiber Bragg grating (FBG) sensors for structural health monitoring, all external factors may affect the measurement accuracy of the sensors and cause measurement errors, so it is necessary to consider some specific factors in a comprehensive manner. In this paper, we theoretically study the average strain transfer rate of the three-layer strain transfer model of a surface-adhesive fiber grating sensor under the effects of temperature change and fatigue load, derive the formula for the average dynamic strain transfer rate under the combined effects of two external factors using the shear-lag method and analyze the parameters of the fiber-optic sensor to correct the error and optimize the measurement accuracy of the sensor in order to better monitor the structure under temperature change and fatigue load. The shear hysteresis method is also used to analyze the parameters of the fiber-optic sensor to correct the errors and optimize the measurement accuracy of the sensor in order to better monitor the real dynamic strain of the substrate under temperature and fatigue loads and provide theoretical guidance for its measurement.
