Multi-parameter real-time monitoring scheme for power transmission lines based on FBG sensors

A multi-parameter real-time monitoring scheme for power transmission line is proposed and experimentally demonstrated.The Fiber Bragg Grating(FBG)sensors are used to sensing the information of temperature and strain in the power transmission lines system,and a monitoring center based on client–server model is established to process and display the sensing information.Several FBG-based power transmission line temperature sensors interrogated based on the developed multi-parameter real-time monitoring scheme is experimentally investigated.The result shows that the system is very useful.

The Circular Birefringence-Insensitive FBG Sensor for Weak Pressure

The influence of the circular birefringence on the measurement performance was analyzed based on the Polarization Properties of FBG in this paper. Due to the circular birefringence, the linear relationship between the max of PDL and pressure has been broken down. To estimate the cross sensitivity, a new parameter named relative peak of PDL (RPPDL) is proposed. Under different circular birefringence, the same pressure sensitivity of sensor has been achieved. The theo- retical analysis and experiment results prove that transverse strain sensor of FBG is insensitive to the circular birefrin- gence by applying the RPPDL. This research can be provided to useful and practical application.

Deformation Measurement of Glass Structure Using FBG Sensor

Glass has been widely used as an important component in structures such as reflection glass curtainwalls,high speed trains,and landscape glass bridges with advantages of transparent and easy to clean,which are exposed to extreme weather conditions and external loads.Over time,these factors can lead to a damage of glass.So the health status of glass structure is critical,which should be routinely monitored to improve safety and provide reliable maintenance strategy.In this paper,fiber Bragg grating(FBG)sensors are used to monitor glass damage based on the fact that the main components of both the optical fiber and the glass are silica,which hints that both optical fiber and glass have the similar mechanical properties.Furthermore,the diameter of FBG installed on the glass structure is small,which has little effect on the beauty of glass.In order to validate the feasibility of the damage monitoring method,one common glass panel model with two-side fixations is loaded impact and static loads respectively,on the upper and lower surfaces of which four FBG sensors and two resistance strain gages are installed.A comparison study among the measured strains from the FBG sensors,those from the resistance strain gages,and those calculated from finite element model(FEM)analysis is conducted and the result obtained with experiments agrees with the element result.Test results show that the FBG sensors can effectively measure the glass deformation or damage under the impact and static load.

A novel successive demultiplexing scheme based on optical-CDMA balanced demodulation for FBG sensor systems

In order to increase the multiplexing density of the fiber Bragg gratings （FBGs） for a low cost per-sensor, based on the analysis of the spectrum shadow distortion （SSD）, a novel successive demultiplexing scheme for FBG sensors has been developed. It is based on the optical cade division multiple access （CDMA） balanced demodulation. A high-density multiplexing-demultiplexing system for FBG sensors has been designed, and corresponding simulation carried out has demonstrated that the FBG sensors＇ reflective signals can still be obtained accurately and respectively, even if FBG sensors＇ operating bandwidths heavily overlap. The SSD has been greatly mitigated.

FBG传感器在起重机械局部损伤监测中的应用研究

光纤布拉格光栅(Fiber Bragg Grating,FBG)传感器自身应变传递特性和敏感范围波动较大,在应用过程中缺少结合被测结构性能和FBG传感器本身结构特点的应用方法。为此,研究FBG传感器在起重机械局部损伤监测中的应用。根据起重机械的内部振动状况构建损伤模型,在FBG传感器光纤的同一位置放置两个不同的Bragg光栅,并根据波长变化采集局部损伤数据,将采集到的数据输入自回归滑动平均模型(Autoregressive Moving Average Model,ARMA)中,提取损伤状态,完成起重机械局部损伤监测。实验结果表明,所提方法的反馈时间低于0.25 ms,监测到的应变数据与实际应变数据差距相近,监测的损伤部位与设定损伤部位一致,证明该方法监测反馈效率和监测精度高,监测效果好,适用于各种环境下的起重机械局部监测工作。

基于正弦式波纹膜片的压差式FBG静力水准仪

为解决建筑物不均匀沉降长期、可靠监测的问题,基于连通器原理,推导了膜片半径r、刚度K、光纤自由段长度l、波长变化量Δλ_(B)等参数和沉降量的线性关系式。以此设计了带有正弦式波纹膜片的压差式光纤布拉格光栅(FBG)静力水准仪,并通过标定试验验证压差式FBG静力水准仪的传感性能。结果表明:此静力水准仪灵敏度不小于13.2 pm/mm,综合误差不大于3.26%,相关性系数均在0.99以上。该型静力水准仪传感性能满足工程结构沉降测量的要求,丰富了FBG静力水准仪的研究,具有理论和现实意义。

基于FBG传感器的卫星天线形变重构技术

针对由温度变化和外界机械载荷等因素引起的卫星天线结构形变重构需求,提出了一种基于光纤布拉格光栅(FBG)传感器的可视化形变重构技术。利用非金属封装材料和聚酰亚胺光纤光栅制备了FBG应变传感器和温度传感器进行应变与温度的测量,采用光纤传感解调系统实现结构的形变重构。搭建了变温环境天线结构模拟试件形变重构测试平台,采用激光测距仪完成对比测试。研究结果表明,通过相同工艺制备的FBG传感器具有很好的一致性,常温下FBG传感测量的误差小于5.94%,变温环境下的测量误差小于6.97%。重构后的曲面能够真实反映模拟试件的形变情况,验证了该系统的有效性。该技术在卫星天线结构形变重构领域中有良好的应用前景。

Implementation of Phase Generated Carrier Technique for FBG Laser Sensor Multiplexed System Based on Compact RIO

This paper presents the fundamental technique of phase generated carrier （PGC） and its realization on compact reconfigurable input and output （RIO） which adopts real-time and field programmable grate array （FPGA） techniques. Improvement of the PGC technique is also introduced by using peak-to-peak value detection method to reduce the influence of variation of the light intensity. A four-element fibre Bragg gratings （FBG） laser sensor system is conducted in the experiment and the demodulated results demonstrate correlation coefficient as high as 0.995 with the reference signal and the dynamic range to be 120dB@63Hz.

表贴式矿用FBG传感器应力传感特性分析研究

本文重点对表贴式矿用光纤布拉格光栅(FBG)传感器应力传感特性进行了分析研究,针对表贴式FBG传感器应力传感特性受基体剪切模量进行系统性的分析,建立表贴式FBG应变三层结构理论分析模型,推导表贴式FBG的应变传递数学表达式,从基体的剪切模量角度分析矿用FBG传感器应力传感特性。通过试验分析总结,得出铜基体材料应变和波长线性关系最佳,可达99.89%,表贴式FBG基体剪切模量越大,应力与波长线性度越好,为矿用FBG传感器结构设计和灵敏度优化提供理论研究基础。

基于FBG的农业大棚土壤温度测量与研究

研究农业大棚土壤温度,对农业生产具有重要意义。针对传统热电偶等传感器测量土壤温度场存在效率低、误差大等问题,该文采用一种基于光纤布拉格光栅(FBG)的温度传感器来监测农业大棚内的土壤温度变化。该方法将封装了FBG串的不锈钢管垂直埋入被测土壤中,采用可调谐激光器法和寻峰算法解调FBG串各传感器波长,在大棚环境下进行了土壤多层温度场测量实验。实验结果表明,土壤内部温度呈余弦函数模型周期性变化。随着土壤深度增加,温度变化逐渐减小,在一定的湿度范围内,土壤湿度越大,浅层土壤温度越低。土壤湿度对深层土壤温度影响较小,太阳辐射对浅层土壤温度影响较大。

Electroless Nickel Plating and Electroplating on FBG Temperature Sensor

Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.

矿用FBG倾角传感器结构设计及传感性能分析

基于杠杆—摆锤结构与力学分析方法,利用差动补偿法消除温度对光纤布拉格光栅(FBG)波长漂移量的影响,建立波长与倾角传感的数学模型,分析矿用FBG倾角传感器传感特性。通过矿用FBG倾角传感器平台标定静态实验分析总结,铜基体表贴FGB传感器精度为1.526%、灵敏度为952.95 pm/(°)、重复性为1.2687%、迟滞性为0.2998%,结果表明:FBG倾角传感性能与实际倾角测量结果具有较好的一致性,为矿用FBG倾角传感器的应用提供理论技术支撑。

Axial Micro-Strain Sensor Based on FM-FBG via Dual-Mode ML-FMF in Sensor Networks

An in-fiber axial micro-strain sensor based on a Few Mode Fiber Bragg Grating (FM-FBG) is proposed and experimentally characterized. This FM-FBG is in inscribed in a multi-layer few-mode fiber (ML-FMF), and could acquire the change of the axial strain along fibers, which depends on the transmission dips. On account of the distinct dual-mode property, a good stability of this sensor is realized. The two transmission dips could have the different sensing behaviors. Both the propagation characteristics and operation principle of such a sensor are demonstrated in detail. High sensitivity of the FM-FBG, ~4 pm/με and ~4.5 pm/με within the range of 0 με - 1456 με, is experimentally achieved. FM-FBGs could be easily scattered along one fiber. So this sensor may have a great potential of being used in sensor networks.

高强钢丝表面封装FBG传感器的温度响应研究

为解决桥梁缆索高强钢丝表面封装光纤光栅应变传感器(HSW-FBG传感器)的温度修正问题,建立HSWFBG传感器的温度响应模型并推导其温度灵敏度系数计算公式,基于正交试验设计并制作9根HSW-FBG传感器,通过水浴试验对传感器的温度响应进行了验证与分析。结果表明:FBG传感器在封装后其温度灵敏度系数出现了较大变化,通过水浴试验验证了HSW-FBG传感器的温度灵敏度系数计算公式的准确性;通过影响参数分析及极差分析,温度灵敏度系数的影响顺序由主到次依次为基体热应力系数、光纤初始波长、封装材料热应力系数、封装层横截面面积,其中基体材料对HSW-FBG传感器温度响应具有决定性作用。HSW-FBG传感器的温度响应研究结果将为其工程应用打下坚实的基础。

预应力锚固区FBG螺旋筋的研制

预应力锚固区的应力集中复杂,其承载和抗裂性能对预应力混凝土结构的安全耐久至关重要。针对锚固区应力应变检测难题,在其螺旋筋中径位置嵌入分布式的FBG,制备能可靠监测环向应变的FBG螺旋筋,并按国标GB/T 14370—2015对M15-9型锚具锚固区进行三组荷载传递试验。试验结果表明:FBG螺旋筋的全部测点均存活有效,能够全程跟踪锚固区应力变化;随着荷载的增加,其内部拉应变逐渐增大,在1.2倍极限荷载下实测出三个试件的螺旋筋实际最大拉应变分别为777.15、710.29、785.50με,其应力均未超过其材料屈服强度,螺旋筋尚处于弹性变形阶段。在0.6~0.8F_(ptk)加载过程中,试件侧表面开始出现竖向劈裂裂缝;1.0~1.2F_(ptk)加载过程中,首条裂缝均发展为主裂缝,同时加载端面出现斜裂缝,裂缝宽度最大值为0.15 mm,均满足规范要求。FBG螺旋筋应变传感器可为锚固区的服役期应力应变监测、预警及其设计方案提供一种有效手段。

考虑混凝土弹塑性的植入式GFRP封装FBG传感器应变传递分析

工程化FBG传感器的封装层引入的应变传递损耗使其具有应变传递误差,需进行应变传递分析。已有研究多聚焦于基体处于线弹性时的应变传递分析,而混凝土结构发生弹塑性变形后的应变传递规律尚未明晰。以植入式GFRP封装FBG传感器为对象,在应变传递分析中引入混凝土的非线弹性本构关系,建立了基体与FBG的应变传递关系,通过有限元模拟验证了该理论推导的有效性。基于理论分析探讨了混凝土弹塑性演化、混凝土标号、传感器半径与标距等因素对应变传递效率的影响,并分析了传感器的尺寸设计。研究表明:平均应变传递率在混凝土弹性阶段变化较小,而到塑性阶段则显著降低,混凝土标号、半径与标距都会对应变传递效率产生较大影响。本研究可广泛用于植入式FBG传感器的应变传递误差修正及设计。

FBG技术监测分析机场跑道沥青加铺层反射裂缝扩展过程

反射裂缝是导致机场跑道加铺层失效的主要病害之一。为分析机场水泥跑道沥青加铺层反射裂缝扩展过程,本文基于光纤布拉格光栅(FBG,fiber Bragg grating)传感技术,提出了可用于实时监测机场水泥跑道沥青加铺层反射裂缝扩展过程的柔性FBG传感器封装方法,并对研发的FBG传感器进行了标定。基于室内组合梁试验,分析了机场水泥跑道沥青加铺层复合结构反射裂缝扩展过程,包括微裂纹萌生与积累、反射裂缝扩展、反射裂缝贯通3个阶段。在反射裂缝扩展初期,FBG传感器中心波长增长速率相对较小;随着反射裂缝逐渐扩展,FBG传感器中心波长迅速增大。结果表明,柔性FBG传感器全部存活且性能完整,验证了其在实时监测机场水泥跑道沥青加铺层反射裂缝扩展过程中的可行性。

液压支架FBG倾角传感器的设计应用

在煤矿井下的支护中,FBG(Fiber Bragg Grating,光纤布拉格光栅)传感技术的应用和支架支护的检测具有一定的价值和重要性,因此需要对支架FBG倾角传感器进行设计,以提高矿采安全性。以A煤矿为例,在介绍采煤工作面概况后,对支架倾角姿态监测系统进行了分析,具体探讨了基于FBG的倾角传感器设计,并从监测原理、准确度补偿等方面进行了讨论。最后从模拟实验角度对FBG倾角传感器的应用价值进行了探讨,得出该倾角传感器能对顶梁、底座及前连杆的倾斜角度进行姿态监测,利于实时掌握支架的支护状态,及时调整支护参数,进一步提高采矿安全性。

基于锁模激光器的FBG电流传感器高速解调系统

智能电网可靠、安全、经济、高效的发展目标,对电流参数的检测速率提出了更高的需求。本文开展了锁模激光器对基于磁致伸缩效应的光纤布拉格光栅(fiber Bragg grating, FBG)电流传感器复用实现高速解调的实验研究,首次将时间拉伸-色散傅里叶变换(time-stretch dispersive Fourier transformation, TS-DFT)技术与光纤电流传感技术进行了结合。固定于磁致伸缩材料表面的FBG能够感知通电螺线管产生的磁场所引发的材料应变。TS-DFT技术可将应力引起的FBG波长偏移映射为时域上反射脉冲的时延偏移实现高速解调。在0~4.5 A电流范围内对2个传感FBG的波长复用进行监测,系统的解调速率高达69.6 MHz,该技术在电流或磁场传感领域有广阔的应用前景。