机敏材料与结构中传感光纤集成技术初探

本文介绍了我我们在机敏材料与结构中集成传感光纤的初步研究成果。主要包括光纤的集成方法、１集成工艺、光纤的引出及其保护等。     

机敏材料中结构状态探测光纤阵列及其信号处理

将一种新颖的、结构简单的“城墙”型光纤传感阵列埋置于复合材料结构内,用于探测结构内应变,应力等状态参数及其变化。对于内埋光纤阵列输出的传感信号,则采用人工神经网络来处理,并给出了Ｂｐ网仿真结果。     

光纤机敏复合材料与结构中的光纤传感器及阵列

介绍了光纤机敏复合材料与结构中常见的光纤局部传感器、光纤分布及准分布式传感阵列的结构与应用。     

探测复合材料结构冲击损伤的内埋光纤陈列

本文介绍将刻蚀处理的多模光纤埋入复合材料结构内组居光纤传感陈列，用于探测复合材料结构由于外部冲击而造成的内部损伤，给出了实验方法与结果。实验显示了该方法探测复合材料结构冲击损伤的可行性。     

灵巧结构与蒙皮中的光纤传感技术

在复合材料结构部件内或蒙皮中埋入光纤传感网络，称为灵巧结构与蒙皮。该技术受到各国政府和军方的高度重视，成为９０年代材料与传感技术的一个热点。     

含光纤编织复合材料试件的制作与实验研究

编织结构复合材料克服了层合结构复合材料层间强度低,损伤容限低等缺点,光纤传感器由于与复合材料有良好的相容性等优点,已广泛应用于层合结构复合材料,文章通过实验研究了光纤偏入编织复合材料试件的工艺以及含光纤试件的成型工艺。将光纤成功地编入三维编织复合材料试件并通过树脂传递模塑（RTM）工艺成型。并对编入试件的光纤在试件受弯时的传感性能进行了研究,     

智能复合材料光纤传感层的研究

光纤自诊断系统是智能复合材料结构的重要组成部分。但是 ,将光纤传感器阵列埋入复合材料是实现智能复合材料的一个难题。解决这一问题的方法是将光纤传感器集成在一起形成一个模块化的便于埋入复合材料中的光纤传感层。本文探讨两种使用聚酰亚胺制作传感层的方法。一种是把光纤传感器阵列埋入聚酰亚胺薄膜中 ;另一种是用作为光学材料的含氟聚酰亚胺制作矩形 (道沟 )光波导和光传感器。后一种方法制作的传感器模块集成度高、可靠性好 ,是值得注意的发展方向。     

检测材料状态的缠绕光纤及OTDR技术

以智能复合材料结构中的损伤估计为目的,提出了一种新颖的利用多模光纤缠绕尼龙筋（或细钢丝绳）式的传感器。将这种传感器组成传感阵列埋置于复合材料内,可以对材料结构的受力、应变等状态参量进行检测。采用ＯＴＤＲ技术实时处理并行分布式传感信号,在复合材料典型构件上的初步实验表明该方法实用可靠,在复合材料智能化研究中有着广阔的应用前景。     

光纤Bragg光栅传感器传感原理及常见结构

根据光纤Bragg光栅传感器的传感原理,以光纤光栅传感器的的常用结构-悬臂梁结构,柱式力结构,膜片式结构,复合材料柔性结构,聚合物封装结构为例对光纤光栅传感器封装方法、使用范围以及各种结构的优缺点做了分析,并根据实际经验介绍了光纤光栅传感器断点的保护方法.     

光纤传感网络用于机敏复合材料的研究

探索采用一种埋入材料或结构内的结构简单、性能优良的刻纹光纤传感阵列对结构内应变、应力以及外部冲击造成的损伤等状态参数进行实时检测。埋置于教－１１飞机复合材料垂尾内光纤网络的实验显示了该方法的可行性。     

基于准分子激光加工技术的内嵌光纤型微流控器件的制备

为了方便、快速、低成本地检测样品,提出一种内嵌光纤型微流控芯片的制备方法.利用248 nm的KrF准分子激光在聚甲基丙烯酸甲酯(PMMA)基片上进行微加工,构建芯片结构,并嵌入腐蚀过的直径35μm的单模光纤,从而形成内嵌光纤型芯片.探讨了准分子激光加工参数以及嵌入光纤的方法.结果表明,用准分子激光加工芯片,可控性好、简便可靠、加工过程可实现无人化.内嵌光纤实现了光纤的相互对准以及光纤对流道中央的对准,可以灵敏地获取样品的光学信号.     

Ultrasonic embedding of nickel-coated fiber Bragg grating in aluminum and associated sensing characteristics

Fiber Bragg Gratings (FBGs) were embedded in metal foil using ultrasonic welding processes. Ultrasonic welding embedding processes, cross-sections of welded samples, the form change and wavelength shift of the Bragg peak during the processes, as well as the sensing characters of embedded FBGs were investigated. To understand the effects of metal foil properties on fiber embedding, optical fibers were embedded in similar and dissimilar metal foil samples. In order to study the effects of protective coating properties on the embedding processes, bare fibers, chemical nickel-plated fibers and chemical-electro nickel-plated fibers were compared in the ultrasonic welding process. Results indicate that only chemical-electro plated fibers and FBGs were successfully embedded in aluminum foils due to good protection and an appropriate matrix metal. Examination of the form change and wavelength shift shows that the FBGs are preserved well after the plating and ultrasonic welding processes. Thermal sensing results show that temperature sensitivity of the FBG was enhanced after chemical-electroplating and further enhanced after embedding in aluminum, which resulted from different thermal expansion coefficients of the SiO₂, aluminum and the nickel layer. Strain sensing results show (i) the embedded FBG remains in good condition when a cyclic tensile load (0–40 N) is applied; (ii) the relationship between wavelength and the applied load shows a linear trend.     

Theory and experiments on birefringent optical fibers embedded inconcrete structures

Theoretical and experimental results on birefringent optical fibers embedded in concrete are presented and discussed. We study the effect of strain on the propagation of light in birefringent fibers embedded in a host material loaded under uniform compression. Both longitudinal and transverse deformations are considered in the analysis since the fiber is embedded along a direction perpendicular to the strain load. The effects of the strain on the birefringence of the fiber and the rotation of the optical axis are studied. The theoretical model is used to determine the best polarimetric system configuration to detect strain. Our experimental work was performed by embedding optical fibers in standard concrete cylinders, attaching resistive electric strain gauges on the surface, and testing the specimens under uniform compressive stress. Optical transmission data from the fiber and readings from the electric strain gauges were simultaneously recorded     

智能结构中光纤智能夹层系统的研究

根据光纤自诊断系统模块化、集成化要求，提出并研制了光纤智能夹层。这种智能夹层易于制作，且制作过程中光纤传感器完好率达100％，智能夹层的埋入对复合材料拉伸强度影响较小。在此基础上，对光纤智能夹层试件进行了轴向拉伸试验。试验表明，在一定应变范围内，单膜交错光纤中光强-应变之间具有良好的线性关系，可以在埋入复合材料之前进行标定。利用智能夹层内的光纤传感器网络和先进的信息处理技术，可以建立结构损伤主动、在线和实时监测系统。     

Embedding optical fibers in metal alloys

This article presents a new method for embedding optical fibers into a nickel alloy and gives the results for a long-term test with thermal cycling of two fiber-optic Bragg gratings embedded in nickel alloy. We embedded these Bragg gratings in a piece of Inconel 600 (a nickel alloy) using vacuum brazing. We then thermally cycled this piece between 500, 525, and 550/spl deg/C for about six months while monitoring the reflected wavelengths of the gratings. We tested two other embedded gratings for 68 hours at 600/spl deg/C. Some microscopic cross sections of the embedded fibers are presented. The results show that fiber sensors embedded in metal can operate reliably at very high temperature and in harsh environments. We hope that the results from the long-term, elevated temperature test will make it possible to apply the technology of fiber-optic sensing in new and demanding monitoring applications, especially at high temperatures in energy production.     

Passive-quadrature demodulated localized-Michelson fiber-opticstrain sensor embedded in composite materials

A strain sensor embedded in composite materials that is intrinsic, all fiber, local, and phase demodulated is described. It is the combination of these necessary elements that represents an advance in the state of the art. Sensor localization is achieved by using a pair of mirror-ended optical fibers of different lengths that are mechanically coupled up until the desired gauge length for common-mode suppression has been reached. This fiber-optic sensor has been embedded in both thermoset (Kevlar/epoxy and graphite/epoxy) and thermoplastic (graphite/PEEK) composite materials in order to make local strain measurements at the laminar level. The all-fibre system uses a 3×3 coupler for phase demodulation. Parameters such as strain sensitivity, transverse strain sensitivity, failure strain, and frequency response are discussed, along with applications     

节点重要性感知的透明虚拟光网络协同映射策略

针对透明弹性光网络环境下虚拟光链路映射过长和频谱碎片问题,该文提出一种节点重要性感知的协同映射算法。在节点映射阶段,设计节点重要性度量准则,评估未映射节点和已映射节点的邻近性,以及光路的频谱紧密度,以缓解链路频谱碎片和增强节点映射的紧凑性。同时,为了降低节点映射成功而链路映射失败的概率,提出一种节点-链路协同映射算法,当成功映射一对相邻虚拟节点时,立即映射他们之间的虚拟光链路,并分配频谱资源,最小化虚拟光链路所映射物理光路跳数。仿真结果表明,所提算法能够使用更少的频谱资源传输更多的虚拟光网络业务,且缩短了虚拟光链路映射长度。     

Scattering from composite laminate strips

An analytical model is developed for a composite laminate consisting of unidirectional fibers embedded in a dielectric slab on a conducting strip. The physics of the problem is formulated in terms of integral equations solved by the method of moments using an entire-domain Galerkin formulation. The effect of fiber spacing, the proximity of the ground plane, and the properties of the embedding dielectric are examined in relation to the nonspecular scattering characteristics of the laminate. Results of this analysis are presented for various limiting cases and are compared with experimental data     

Response of FBGs in Microstructured and Bow Tie Fibers Embedded in Laminated Composite

Fiber Bragg gratings in bow tie fiber and highly birefringent microstructured optical fiber are embedded in a carbon fiber reinforced epoxy. The Bragg peak wavelength shifts of the embedded gratings are measured under controlled bending, transversal loading, and thermal cycling of the composite sample. We obtain similar axial and transversal strain sensitivities for the two embedded fiber types. We also highlight the low temperature dependence of the Bragg peak separation of the microstructured fibers, which is an important advantage for this application. The results show the feasibility of using microstructured fibers in structural integrity monitoring.     

Transversal Load Sensing With Fiber Bragg Gratings in Microstructured Optical Fibers

We present fiber Bragg grating based transversal load sensing with a highly birefringent microstructured optical fiber. For the bare fiber, the change of the Bragg peak separation under a transverse line load was simulated with a finite-element model and experimentally verified. We also show that microstructured optical fibers with fiber Bragg gratings can be successfully embedded in a carbon fiber reinforced composite material. The linear dependence of the Bragg peak separation to a transversal stress in the composite sample was measured to be 15.3 pm/MPa.