超低温宽温域环境下FBG传感器应变标定方法

Strain Calibration Method of FBG Sensor in Ultra⁃low Temperature and Wide Temperature Range

在某超低温风洞结构健康监测的工程中,光纤光栅传感器被用来实时监测风洞洞体结构变形,然而超低温及宽温域的环境会极大地影响应变测量精度。为解决光纤光栅传感器在-196℃至常温范围的应变测量的温度影响,进一步提高测量精度,提出了一种超低温宽温域环境下的光纤布拉格光栅(fiber-opticBragggrating,简称FBG)传感器应变灵敏度系数标定方法。该方法通过一套超低温宽温域标定系统对FBG传感器在-196℃~20℃的多个温度点的应变灵敏度系数进行了试验测量,利用该标定结果修正超低温宽温域环境下温度对应变的测量结果,可有效提高光纤光栅传感器的应变测量精度。试验还发现,FBG传感器的应变灵敏度系数呈现出随温度降低而升高的规律,该结论对进一步开展超低温宽温域环境下FBG应变传感器温度补偿研究奠定了基础。

In a project for monitoring the health of ultra-low temperature wind tunnel structures,the light grating sensor is used to monitor the deformation of the wind tunnel body in real time. However,the environment of ultra-low temperature and wide temperature range greatly affects the accuracy of strain measurement. In order to solve the temperature influence of strain measurement of fiber Bragg grating(FBG)sensor from -196℃ to normal temperature range and further improve the measurement accuracy,this paper proposes a strain sensitivity coefficient calibration method,which measures the strain sensitivity coefficient of FBG sensor at multiple tem-perature points from -196℃ ~ 20℃ through a set of ultra-low temperature wide temperature domain calibration system. Moreover,the calibration result is used to correct the ultra-low temperature wide temperature range. The measurement result of the temperature corresponding to the environment can effectively improve the strain measurement accuracy of the fiber grating sensor. The experimental results also show that the strain sensitivity coefficient of FBG sensor increases with the decrease of temperature. This conclusion lays an important foundation for further research on temperature compensation of FBG strain sensor in ultra-low temperature wide temperature range environment.