凹槽内嵌式封装光纤光栅应变传感器的温度特性

内嵌预压式封装解决了光纤光栅传感器存活率低、监测量程不足等问题,实现了光纤光栅传感器对钢绞线应变的实时健康监测。光纤布拉格光栅(Fiber Bragg Grating,FBG)传感器主要受轴向应变和温度特性影响,为保证其内嵌封装后对钢绞线应变监测的可靠性,以温度为变化参数对其进行水浴恒温试验,对比分析在5~100℃过程中FBG传感器内嵌式封装前后中心波长变化。试验结果表明:FBG的中心波长随温度升高呈线性增长,与初始波长无关;在钢绞线中心丝凹槽封装裸FBG后,温度灵敏度增大了1倍;当钢绞线使用环境温差达到30℃,温度的交叉影响可使FBG传感器的应变测量误差达到7.6%以上,且钢绞线应变越小误差越大;应在钢绞线中心丝不受力部位串联封装1个FBG传感器,以实现温度补偿减少误差。试验结束后,FBG传感器封装完好,所测试验数据仍具有良好的线性度和重复率,对温度有较好的适应性,为自感知钢绞线的工程应用提供了可靠依据。

Temperature Characteristics of Fiber Bragg Grating Strain Sensor with Groove Embedded Package

Embedded pre-pressed package solves the problems of low survival rate and insufficient monitoring range of fiber grating,and realizes real-time health monitoring of steel strand strain by fiber grating sensor.The FBG(Fiber Bragg Grating)sensor is mainly affected by the axial strain and temperature characteristics.In order to ensure the reliability of strain monitoring of steel strand after the embedded packaged,the temperature was taken as the change parameter to carry out the constant temperature test in water bath.The changes of central wavelength of FBG sensor before and after the embedded packaging in the temperature range of 5~100℃were compared and analyzed.The experimental results show that the central wavelength of FBG increases linearly with the increase of temperature and is independent of the initial wavelength.The temperature sensitivity of bare FBG doubles after packaging in the central wire groove of steel strand.When the ambient temperature difference of steel strand reaches 30℃,the cross-influence of temperature can make the strain measurement error of FBG sensor reach more than 7.6%,and the error increases with the decrease of strain.A FBG sensor should be packaged in series at the non-force part of steel strand to reach temperature compensation and reduce errors.After the test,the FBG sensor is well packaged,the test results with good linearity and repeatability,and has good adaptability to temperature,which provides a reliable basis for the engineering application of self-sensing steel strand.