光纤布拉格光栅电镀保护方法的研究

提出一种在布拉格光线光栅(FBG)表面电镀金属的方法,以达到保护光纤光栅的目的.介绍了镀前预处理、化学镀以及电镀过程,确定了镀液配方及工艺;并进行了温度传感试验.通过对实验结果的分析,表明这种方法不仅可以获得厚度理想的金属保护层,同时可以提高光纤光栅的温度灵敏度.     

光纤光栅传感器设计及解调仪研发

针对油气井测试监测技术需求与应用,结合现有光纤及光栅传感技术,研制油气井高温高压光纤光栅传感仪。探明飞秒激光刻写光栅的光谱特性差、制备重复率低等问题的内在机制,设计制备温度和压力可以同时测量的光纤光栅传感器件,解决油气井下高温、高压、强腐蚀性等苛刻工况对灵敏度、精度、稳定性造成的影响,为光纤传感器在油气井钻井、完井、测试等领域获得广泛应用奠定基础。通过仪器研制的原始创新,推动油气井油气井测试监测技术的发展,提高石油开采的效率。     

基于光纤传感技术的输电杆塔倾斜传感器研究

针对输电杆塔的监测研究了一种基于光纤布拉格传感技术的倾角传感器,该传感器内固定有一根等强度悬臂梁,在悬臂梁两侧各粘有一个光纤布拉格光栅(FBG),在其自由端挂有一重物。当传感器倾斜时,重物带动等强度自由端重物产生挠度,使传感器的中心波长发生变化,通过监测中心波长来达到监测杆塔倾斜的目的。实验表明:该光纤布拉格光栅倾角传感器的灵敏度为0.317 2nm/°,线性度为1.030%FS,迟滞性误差为0.364%FS,具有零点漂移小的特点。     

武工大成功研制光纤光栅传感器

主要应用于石油化工行业的光纤光栅传感技术 ,日前在武汉理工大学研制成功 ,并获得湖北省科技进步一等奖 ,为我国石化业重大工程的安全检测提供了有力的保证。武工大研制的光纤光栅传感器除了具有普通传感器的本质防爆、抗电磁干扰外 ,还可实现现场无电检测 ,从本质上排除了一般光强型传感光信号传输中各种光强起伏引起的干扰 ,避免了一般干涉型传感器中相位测量的不清晰和对固有参考点的需要。该技术在一根光纤中串换多个光栅进行分布式测量 ,构成各种形式的光纤传感网络 ,因此可对大型油罐内部的温度变化进行高分辨率和大范围的测量。目前…     

基于光纤光栅的复合材料动态称重系统研究

本文利用光纤布拉格光栅(FBG)的智能感知特性研制开发一种复合材料结构,用以汽车的动态称重.采用轴荷称重的方法进行动态称重,其基本思想是将光栅布设在称体结构的承重梁上,利用光栅监测称体的变形,根据己知系统的动态特性和实测的动力响应,即称体的变形,反算出结构所受的动态激励,从而获得汽车载荷.首先,基于光纤传感器的原理和称重结构的力学特性,推导出载荷识别的算法.对称重系统进行动态实验,结果表明了以上算法的合理性,并对误差进行了分析.     

基于光纤布拉格光栅的复合材料振动性能研究与损伤监测

采用光纤布拉格光栅(FBG)对碳纤维增强复合材料(CFRP)的振动性能和损伤类型进行研究。采用落球击打碳纤维增强复合材料悬臂梁自由端,使复合材料悬臂梁产生谐振。通过测量复合材料悬臂梁的谐振频率,计算其阻尼损耗因子,得到无损伤碳纤维复合材料的振动性能。在此基础上,对碳纤维增强复合材料人为引入损伤,利用FBG测量其损伤状态下的谐振频率,依据谐振频率分析判断损伤类型。研究结果可对碳纤维增强复合材料的振动性能研究和损伤监测提供参考。     

光纤光栅传感器在道路测试及工程应用的研究进展

路面结构内部温度、湿度、应力和应变等参数的测试一直是道路测试领域的重点和难点,随着光纤光栅传感技术的发展,为道路测试领域提供了新方法;为了论证光纤光栅传感技术在道路测试领域的可行性,介绍了光纤光栅传感系统的基本结构,从温度和应变传感器基本原理出发,综述了光纤光栅传感器的室内探索性研究和在实际路面温度和应变测试的成果.最后介绍了光纤光栅传感器在其他工程,包括桥梁、隧道及机场跑道中的应用情况,并分析了光纤光栅在道路测试工程中推广使用所面临的困难和发展方向.     

光纤光栅机敏混凝土的研究

结合光纤光栅传感技术的优点,提出了一种新型光纤光栅机敏混凝土原理,并对该原理和特性进行了分析,阐明了实现光纤光栅机敏混凝土原理和系统的关键技术和方法,并通过原理性实验得以验证.光纤光栅机敏混凝土在结构的长期状态监测和损伤诊断方面具有良好的前景.     

弹性体结构光纤光栅应变传感器的设计与性能研究

为提高光纤光栅传感器的精度和长期使用稳定度,在分析其应变响应机理和研究现状的基础上,设计基于应变弹性体封装的光纤光栅应变传感器,封装材料采用305不锈钢。力学传递原理和Ansys力学分析结果都表明:该传感器能够有效地通过弹性结构将应变传递到光纤光栅上。利用激光切割技术制作不锈钢光纤光栅传感器封装壳体,在-2 000~2 000με的测量范围内,实验测得其应变灵敏度为1.21pm/με、线性度达0.999 6、检测精度不大于1με、稳定度不大于±3με。     

基于FBG的复合材料内固化过程应力和温度监测

阐述了玻璃纤维增强塑料管道内加热固化系统结构,采用光纤布拉格光栅传感器检测原理,设计了内固化过程应力和温度监测系统,重点解决了光纤光栅的交叉敏感和芯模旋转问题,监测分析了玻璃纤维增强塑料板固化过程的内部应力和温度变化历程,实践证明,该监测系统实时性高,数据检测精确.     

光纤布拉格光栅压力传感器标定中的不确定度研究

研制了一种量程为10k N的光纤布拉格光栅压力传感器标定装置,可实现光纤布拉格光栅压力传感器的标定和静态测试。对光纤光栅解调仪获得的中心波长和标准测力仪的压力值进行最小二乘拟合,求出静态标定系数,并分析了标定装置的不确定度来源以合成不确定度。试验结果表明:光纤布拉格光栅压力传感器的响应灵敏度为9.77×10~(-5)nm/N,线性度2.79%FS,经二阶拟合后重复性误差2.61%FS,标定装置的A类不确定度5.73N。     

Assessment of thermoset cure‐induced strains by fiber bragg grating sensor

Composites based on thermosetting resin and reinforcement fibers present generally unwanted residual internal stresses inherent to their elaboration process. In this article, different curing experiments of thermosets (isothermal and anisothermal) were monitored using optical fiber Bragg grating (FBG) sensors and thermocouples, to assess the cure‐induced strains. A thermokinetic model evaluates the degree of conversion of the resin. At the onset of stress transfer to the optical fiber, the degree of conversion ranges between 0.63 and 0.68. During curing, the FBG deforms under chemical shrinkage with an amplitude widely lower than the expected chemical strain, showing that the FBG signal is not directly related to the actual chemical shrinkage. However, once the resin is cured, the FBG sensor provides directly the coefficient of thermal expansion of the resin, as function of temperature and degree of conversion, reached in the different experiments. POLYM. ENG. SCI., 54:1585–1594, 2014. © 2013 Society of Plastics Engineers     

Crack monitoring using multiple smart materials; fiber-optic sensors & piezo sensors

ABSTRACT

This article focuses on health monitoring of structures using multiple smart materials. In this research, two fiber-optic sensors, namely fiber Bragg grating (FBG) and fiber-optic polarimetric sensor (FOPS), are investigated for damage detection in the beam specimen. FBG is used for local strain measurement while FOPS is used for global strain measurement. Both FBG and FOPS show significant changes in the strain due to damages in the specimen. Also, at the center of the specimen, piezoelectric wafer active sensor (PWAS) is attached. The electromechanical admittance (EMA) signature of the specimen beam is recorded by PWAS. The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed, and it is shown that the peak amplitudes respond differently to damages and to change in loading. Thus, multiple smart materials (FBG, FOPS, and PWAS) are used to get improved information on the health of the beam.     

悬臂梁结构光纤光栅电流传感器的优化

针对电力系统对电流测量高精度的要求,设计了一种基于等强度悬臂梁结构的光纤光栅电流传感器。将两根光栅分别粘贴于等腰三角形结构的悬臂梁上下表面,末端永磁体材料振子置于两螺线圈中间。当螺线圈接通电流时,形成的磁场将会引起永磁体振子偏移,进而引起光栅中心波长的变化。采用差分方式建立电流大小与光栅波长变化之间的关系,在提高测量灵敏度的同时消除了温度对测量结果的影响。实验结果表明:在0~5A的范围内,利用光纤光栅波长变化可准确反演待测电流值,与理论计算值相比,误差小于1.2%。     

Strain Profile Measurement for Structural Health Monitoring of Woven Carbon-fiber Reinforced Polymer Composite Bonded joints by Fiber Optic Sensing Using an Optical Backscatter Reflectometer

In order to monitor crack initiation and propagation under static and fatigue loading in adhesively bonded joints, strain profile measurement such as backface strain (BFS) is a very efficient technique. In single lap (SL) joints, crack initiation and propagation in the glue line can be monitored by detecting the negative peak of the strain profile. Therefore, the accuracy of the monitoring system greatly depends on detecting the strain profile correctly and accurately. Previously, an array of electrical strain gages as well as fiber Bragg grating (FBG) sensors had been used successfully to capture the profile of BFS of a SL joint by applying sensors on the backface of an adherend, near the overlap zone. In this work, the backface technique is improved by replacing an array of strain sensors by an ordinary optical fiber (without FBG sensors) connected to an optical backscatter reflectometer. The great advantage of this system over the more conventional arrays of FBG is that the entire length of the fiber can be used for sensing strains, and hence it provides a better spatial resolution. The experimental results are compared with finite element analyses, which were further validated by two-dimensional digital image correlation measurements.     

Study of a Surface Plasmon Resonance Optical Fiber Sensor Based on Periodically Grating and Graphene

Silicon - In this paper an optical fiber sensor based on plasmonic resonance of graphene and periodically grating is designed and investigated. The proposed sensor consists of an optical fiber core...     

Monitoring of cure‐induced strain of an epoxy resin by fiber Bragg grating sensor

In this study, we present a method to detect cure‐induced strain in an epoxy resin (EP) with a Fiber Bragg Grating (FBG) sensor. By embedding the optical fiber into the EP resin the characteristics during isothermal cure (gel point, vitrification) could be precisely detected due to changes in the fiber strain. In a follow up dynamic temperature scan the coefficient of thermal expansion and the glass transition temperature (T_g) of the fully cured EP were determined by the FBG sensor technique. All results obtained by the fiber optical method showed a very good agreement with those deduced by independent techniques, viz. rheological measurements, differential scanning calorimetry, and thermomechanical analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

通过光纤传感器和微型热电偶简单耦合方法测量内部平均应变和温度的变化来监测复合材料液体树脂灌注成型工艺

作为复合材料液态成型技术（LCM：Liquid Composites Moulding）中的一种,液体树脂灌注成型工艺（LRI：Liquid Resin Infusion）以其良好的发展前景已经越来越多地被先进复合材料制造产业所关注。为了提高对液体树脂灌注成型工艺的认知并从而达到对其良好的控制度,需要在实际制造工艺进行...     

基于FBG传感的正渗透膜界面剪切力变化特性

针对正渗透（FO）过程中膜面剪切力的分布式测量问题,基于光纤光栅（FBG）传感技术提出一种膜面剪切力的实时测量方法。研究了不同入口流速对剪切力分布、水通量和反向盐通量的影响,并对膜面的水力学特性进行分析。结果表明,FBG技术能够较好地给出FO膜组件表面流速的变化状况。膜面各位置的剪切力均呈现周期性的变化,在FO膜表面切向方向上,剪切力呈现空间分布的不均匀变化,直接导致了渗透通量的变化。增大入口流速能有效地改善膜面各位置的冲刷作用,但采用较大的入口流速才能使膜面距离入口较远位置的剪切力得到明显的提高。膜组件两侧剪切力的同步增加有利于提高膜通量,但单纯增加剪切力并不能更好地减缓浓差极化而提高水通量。