Aerospace-grade surface mounted optical fibre strain sensor for structural health monitoring on composite structures evaluated against in-flight conditions
Aerospace-grade surface mounted optical fibre strain sensor for structural health monitoring on composite structures evaluated against in-flight conditions
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DOI：
10.1088/1361-665x/ab1458
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发表时间：
2019-06-01
影响因子：
4.1
通讯作者：
Berghmans, Francis
中科院分区：
文献类型：
--
作者：
Goossens, Sidney;De Pauw, Ben;Berghmans, Francis
多年来，人们一直在研究光纤传感器作为支持航空航天应用中结构健康监测 (SHM) 的首选传感器。更具体地说，光纤布拉格光栅 (FBG) 传感器可以提供精确的应变测量，从而返回有关其所附着的结构的机械应变状态的有用数据。该功能可以用于检测飞机结构中的损坏。然而，有关保护光纤并将其粘合到最先进的飞机复合材料的解决方案的报道却很少。文献中报道的大多数使用光纤传感器进行航空航天 SHM 相关应用的原理验证演示确实依赖于以大多数未指定的方式粘合到各向同性金属表面的未封装光纤传感器。传感器的操作、粘合材料和粘合程序均未针对全套标准化飞行条件进行耐久性测试。在这项工作中，我们提出了一种特殊涂层 FBG 传感器及其在航空航天级复合材料上的永久安装，并且我们证明了与航空航天飞行条件的兼容性。为此，我们通过将安装的传感器暴露于全套实际飞行条件之前和之后的反射光谱相关联，彻底评估 FBG 传感器的运行质量。我们还评估了 FBG 测量的应变差异，因为粘合线中的任何损坏都会导致应变释放。所应用的测试条件基于航空航天标准，包括温度循环、压力循环、暴露于湿度和液压油以及疲劳载荷。我们表明，代表飞行条件的应用环境和机械载荷对粘合线和传感器信号质量的影响可以忽略不计，因此得出结论，可以考虑将其用于航空航天级复合材料的 SHM。
Optical fibre sensors are being investigated since many years as candidates of choice for supporting structural health monitoring (SHM) in aerospace applications. Fibre Bragg grating (FBG) sensors, more specifically, can provide for accurate strain measurements and therefore return useful data about the mechanical strain state of the structure to which they are attached. This functionality can serve the detection of damage in an aircraft structure. However, very few solutions for protecting and bonding optical fibres to a state-of-the-art aircraft composite material have been reported. Most proof-of-principle demonstrations using optical fibre sensors for aerospace SHM-related applications reported in literature indeed rely on unpackaged fibre sensors bonded to isotropic metallic surfaces in a mostly unspecified manner. Neither the operation of the sensor, nor the adhesive material and bonding procedure are tested for their endurance against a full set of standardized in-flight conditions. In this work we propose a specialty coated FBG sensor and its permanent installation on aerospace-grade composite materials, and we demonstrate the compatibility with aerospace in-flight conditions. To do so we thoroughly evaluate the quality of the operation of the FBG sensor by correlating the reflection spectra of the installed sensors before and after exposure to a full set of realistic in-flight conditions. We also evaluate the difference in strain measured by the FBG, since any damage in the adhesive bond line would lead to strain release. The applied test conditions are based on aerospace standards and include temperature cycling, pressure cycling, exposure to humidity and hydraulic fluid and fatigue loading. We show that both the bond line and the quality of the sensor signal were negligibly affected by the applied environmental and mechanical loads representing in-flight conditions and therefore conclude that it can be considered for SHM of aerospace-grade composite materials.