基于光谱特征分析的光纤光栅腐蚀传感器研究

针对航空航天领域铝合金结构服役过程腐蚀监测需求，提出了一种基于铝质细管结构的预载荷型光纤光栅腐蚀传感器。给出了铝合金结构腐蚀在役监测机理，得到光纤光栅反射光谱特征与铝质细管厚度变化之间的理论关系模型，构建了酸碱环境下的光纤光栅腐蚀监测试验系统。通过在细管内部配置不受力且仅感受温度变化的光纤光栅传感器，解决了被测目标的温度与应力交叉敏感问题。研究表明，这种铝质细管封装设计不仅可以感受腐蚀对其力学性能的影响，还能够屏蔽外界腐蚀因素对管内光纤感知器件的干扰。随着金属管腐蚀程度加深，其管壁逐渐变薄，光纤光栅反射光谱逐渐向短波长方向偏移，且管壁厚度变化与光栅中心波长偏移量之间呈较好单调关系。这些特性能够为进一步开展基于光纤感知器件的机械结构在役腐蚀监测研究提供有益帮助。

The Research on Optic Fiber FBG Corrosion Sensor Based on the Analysis of the Spectral Characteristics

Aiming at meeting the need of aluminum corrosion monitoring in aerospace field，a pre-load type fiber grating corrosion sensor based on an aluminum thin tube structure is proposed. The corrosion sensor of aluminum alloy structure in-service monitoring mechanism is studied, a theoretical model about the relation of FBG reflection spectral chasacteristics and aluminum thickness variation is also obtained. Optical fiber grating corrosion monitoring test system based on the capillary structure of aluminum alloy is constructed by acid-base environment. The problem of cross sensitivity of temperature and strain is solved. by configuring an optical fiber grating which is not affected by strain and only sensitive to temperature inside the aluminum alloy tube. The results shows that he aluminum tube packaging design not only can sense the effects of corrosion on the mechanical properties, but also can interference shielding effect of corrosion on the tube optical fiber sensing device. With the deepening of the metal tube corrosion and aluminum alloy tube thickness gradually thinning, fiber grating reflective spectrum gradually shift to the short wavelength and the wall thickness and the grating center wavelength offset has a good monotonic relation. These characteristics can provide useful help to further research corrosion online monitoring based on optic fiber sensor.