为研究适于大型工程长期健康监测的耐久性光纤光栅(FBG)应变传感器,提出并实现了传感光纤无机一聚合物一金属的耐久性组合式封装。对传感元件应变传递的理论计算结果表明,光纤的应变传递机制主要依赖于封装结构的无机内核,金属外套用于工程安装初期对无机内核的保护,聚合物主要起这两者间的连接作用,其应变传递机制被抑制,故即使其力学或材料性能发生转异或劣变,亦不对传感器的耐久性产生显著影响;应变测试的理论分析及模型实验结果均表明,相对于普通聚合物封装的FBG传感器,组合式封装传感器的检测精度有明显提高,验证了理论分析结果的可靠性。
A combined encapsulation of sensing optic fiber with inorganic material, polymer and metal is proposed and accomplished successfully. The strain transmission analytical results show that the major strain transmission mechanism depends largely on the inorganic inner core within encapsulation structure, and with outside metal tube serving as protection for sensors during-installation within engineering, polymer layer is used mainly to connect the inner and outside structures, while its strain transmission action is inactivated. Therefore, even if the mechanical or material performance changes in an unfavorable or a poor manner, the durability of sensors will not be affected accordingly. The analytical and experimental results of sensor strain test models both show that, compared with ordinary polymer encapsulated FBG sensors, the test precision of combined encapsulated sensors is improved noticeably, which verify the reliability of analytical conclusions.