埋入式光纤光栅界面应变传递机理与误差修正

光纤光栅应变传感的准确程度主要取决于光纤、保护层和黏贴层以及基体材料的物理力学性能,即各层间应变传感的界面传递特性.本文以埋入式光纤光栅作为研究对象,推导出了考虑多层界面应变传递的光纤光栅应变传感的统一表达式.通过定义平均应变得到了光纤光栅应变传感的误差与修正公式.针对自行开发的埋入式光纤光栅管式封装应变传感器和FRP-OFBG应变传感器,研究了相应的应变传递误差规律和影响因素,给出了相应的误差修正系数,并通过试验加以验证.为埋入式光纤光栅封装应变传感器的开发与工程应用提供了理论基础.

Interface strain transfer mechanism and error modification of embedded FBG strain sensors

It has been widely accepted that optical fiber Bragg grating(FBG) can be regarded as a strain sensor for structural health monitoring due to its prominent advantages.The practical accuracy of the FBG strain sensor is highly dependent on the physical and mechanical properties,namely the interface strain transfer characteristics between the layers among the bare optical fiber,protective coating, and adhesive layer and host materials.Taking practical embedded FBG strain sensors as examples,the general expression of multilayer interface strain transfer is first inferred.Secondly,the error and error modification expression are obtained based on defining average strain.Finally,the strain transferring error and affection factors of embedded tube-encapsulated FBG and FRP-OFBG strain sensors developed by the authors are analyzed and the corresponding error modification coefficients are also given and tested by experiments.The research results are the basics of the development and practical application of the embedded FBG-packaged sensors.