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光纤布拉格光栅(FBG)传感器是智能金属结构首选的信息传输与传感的载体,埋入金属材料内部的FBG传感器必须要经过适当保护,金属镀层是最有效的保护方法之一。FBG经过镀前预处理,通过化学镀方法可获得均匀的金属保护镀层。针对金属保护镀层,应用弹性力学基本原理分析了由于镀层与FBG传感器的热膨胀系数不同而产生的热应力,建立了镀层厚度对FBG温度传感性能影响的数学模型。镀镍FBG的升温和降温传感实验表明,升温时的实际温度灵敏度系数与模型值之间误差为6.22%,降温时的实际温度灵敏度系数与模型值之间误差为6.75%。与裸FBG相比,化学镀镍后的FBG温度灵敏度系数提高1倍多。结果表明该温度模型从理论上解释了镀层金属热应力对FBG起到的温度增敏作用。
Fiber Bragg Grating (FBG) sensors are the preferred media for information transmission and sensing in smart metal structures. The FBG sensors embedded in the metal material must be properly protected. Metal plating is one of the most effective protection methods. FBG pre-plating through the pre-plating, electroless plating method can be uniform metal protective coating. Aiming at the metal protective coating, the thermal stress caused by the difference of thermal expansion coefficient between the coating and the FBG sensor was analyzed based on the basic principle of elasticity, and the mathematical model of the influence of coating thickness on the FBG temperature sensing performance was established. The experiment of heating and cooling sensing of the nickel-plated FBG shows that the error between the actual temperature sensitivity coefficient and the model value is 6.22% when the temperature is raised, and the error between the actual temperature sensitivity coefficient and the model value when cooling is 6.75%. Compared with bare FBG, electroless nickel FBG temperature sensitivity coefficient more than doubled. The results show that the temperature model theoretically explains the temperature sensitizing effect of the metal thermal stress on the FBG.