专利摘要

200510010505.7埋入公路中的光纤光栅传感器及其封装方法本发明提供的是埋入公路中的光纤光栅传感器及其封装方法。它包括光纤布拉格光栅传感器,在光纤布拉各光栅传感器外有玻璃纤维板封装,光纤布拉格光栅的延长线上套有保护套管。将光纤布拉格光栅的延长线穿入保护套管中,使光纤布拉格光栅的延长线位于保护套管中,然后把光纤布拉格光栅和延长线熔接在一起,最     

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.     

复合材料层合板工程常数的光纤光栅测试与分析

复合材料工程常数的精确测试是合理有效开展复合材料结构力学分析与评估的基础。采用埋入式光纤光栅测试技术对复合材料结构应变特征进行测量,可有效获取复合材料的工程常数,如弹性模量、泊松比等。本文将光纤光栅与引伸计、应变片的单向应变测试结果进行了对比,得出不同测试方法下弹性模量的结果,验证了光纤光栅测试方法的可靠性和有效性。进一步通过在复合材料试件内部分别铺设横向及纵向的光纤光栅,对复合材料试件的泊松比进行了测试,并与应变片的测试结果进行了对比。试验结果表明,光纤光栅相对于应变片测试灵敏度更高,测得的泊松比数值更为稳定。     

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。     

内埋光纤光栅碳纤维增强复合材料层压板力学性能及拉伸应变监测

将不同数量的光纤光栅埋植于复合材料层压板层间部位,研究了光纤光栅的埋植数量对层压板拉伸和压缩性能的影响及光纤光栅埋入对层压板层间结构的影响。此外,利用埋植在层压板内部的光纤光栅监测了层压板在拉伸过程中的应变变化,并与应变片监测结果进行了对比。试验结果表明,当在复合材料层压板中沿纤维方向埋入光纤光栅时,复合材料0°拉伸强度和模量略有降低。而当光纤光栅垂直于纤维方向埋入复合材料内部时,复合材料的90°拉伸强度和模量略有提高。对于压缩性能而言,由于光纤光栅在压缩过程中发生脆断,在复合材料内部产生损伤源,导致复合材料压缩强度有所降低,但当光纤光栅埋植数量较小时,对压缩模量的影响较小。层间形貌的显微观察结果表明,光纤光栅沿纤维方向埋入复合材料内部,在光纤光栅周围未形成树脂富集区,反之则将出现明显的富树脂区。     

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。     

超高压压缩机管道内气流脉动的应变片测量方法研究

由于超高压压缩机管道压力高,且很多介质为易燃易爆介质,出于安全性考虑,超高压管道的压力脉动一般不允许采用动态压力传感器侵入管道进行直接测量,只能采用间接测量的方法。本文对采用应变片测量管道表面应变,进而间接测量管道压力脉动的方法进行研究。首先,在静水压条件下,对管内压力—表面应变的关系进行标定。在该条件下,通过应变片测量得到的管内压力与管内实际压力的误差小于3%。然后,根据该标定关系对超高压压缩机管道的气流脉动进行测量。测量得到二级进气管道近气缸处脉动峰-峰值为21%,二级排气管道近气缸处的脉动峰-峰值为27%,脉动频率主要集中在前3阶。将测量得到的管内脉动压力作为振动激励,对二级进气管道振动应力进行有限元仿真。结果表明,有限元模型计算所得的管道表面应变与测量值在时域及频域特性上吻合较好。上述研究表明采用应变片测量压力脉动的方法具有一定的准确性,能较好地测量管道压力脉动的幅频特征,具有工程应用的可行性。     

三种结构光纤光栅应变传感器应变灵敏度分析研究

基于光纤光栅应变传感器的应变传感理论以及封装技术,针对"矩、工、回"三种结构的基片式光纤光栅应变传感器进行了有限元仿真分析,在相同载荷作用下三种结构传感器的应变灵敏度差别较大,其中"回"型结构传感器具有更高的灵敏度和适用性。     

用于承压构件的在线光纤监测技术研究

分析了分布式光纤检测系统和光纤光栅检测系统在实验室材料疲劳试验中的应用。基于光纤在线监测的试验研究,分析了该方法的优缺点,提出了应用于在役压力容器和工业管道系统的光纤监测实施方法。     

光纤传感及其在管道监测中应用的研究进展

管道安全关系到人类生命和财产安全,及时掌握管道结构健康状态是确保管道安全运行的重要前提。光纤传感技术的不断发展,使其在各个领域得到广泛研究与应用,特别是为管道结构的安全监测提供了技术保障。介绍了分布式光纤传感、光纤光栅传感、阵列复用传感、以及光纤智能传感的基本原理及关键技术,对其性能和特点进行了对比分析。在此基础上,阐述了各种光纤传感技术在管道监测中的具体应用,包括管道结构监测、管道泄漏监测以及管道腐蚀监测。通过对传感技术的不同应用进行比较分析,总结了各传感技术应用的特点和进一步研究发展的方向,指出光纤传感技术在管道监测方面具有的巨大优势和广泛的应用前景。     

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...     

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.     

Influence of Cure Regime on the Strain Development in an Epoxy Resin as Monitored by a Fiber Bragg Grating Sensor

In this paper, the effects of different cure regimes on the strain development in an anhydride‐cured epoxy resin were investigated by fiber optical measurements. The course of the strain signal was detected by an embedded fiber Bragg grating sensor in the unconstrainedly curing epoxy. The build‐up of strain was detected for various cure regimes differing in the dwelling times of the first isothermal step, heating rates to the cure temperature, and final curing temperatures, respectively. Characteristic points (gelation, vitrification) of the cure regimes were identified by conversion‐ and T_g‐determinations via DSC and assigned to changes of the FBG signal. The fiber Bragg sensing technique allowed us to find those variables of the cure regimes which mostly affect the strain development and thus, the level of the residual strain. It was established that the dwelling time and heating rate to the cure temperature influence markedly the residual strain whereas the cure temperature affects this value to a lesser extent for the selected cure regimes. So, the above parameters should be selected properly for an optimum cure regime characterized by the build‐up of a minimum residual strain.

     

Residual Stress Determination Using Strain Gage Measurements

A strain gage technique, which relates the prior residual stress state in a material to the strain data obtained by fixing a strain gage on one surface and grinding off the other, has been proposed previously. In the current work, a generalized solution for obtaining an arbitray residual stress profile from strain gage data is presented. Numerical analysis using the solution indicates that the formulation is insensitive to random errors of 10% or less in the experimental data. Based on the results of the analysis, a procedure for determining stress profiles from strain gage data is outlined. Experimental data for tempered glass was analyzed using the technique proposed. The stress profiles predicted are in good agreement with independent observations using indentation and strength data.     

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.     

Strain effect on recovery behaviors from circular deformation of natural rubber vulcanizate

The recovery behaviors of vulcanized natural rubber from circular deformation were studied by varying sample length to investigate the influence of the degree of applied strain to the sample. The stress and strain varied uniformly across the thickness of the sample, and the degree of applied stress and strain to the sample decreased with increasing the sample length. The linear sample was made into a circular form and thermally aged in a convection oven. The recovery was measured after removing from the circular deformation. The recovery increased by decreasing the sample length. The difference in recoveries of the samples with different lengths reduced at high temperature. The short sample had higher heat‐resisting property for recovery than the long sample. The experimental results were explained by the rearrangement and stabilization of the deformed rubber chains as well as the crosslink density change. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Determination of Residual Stress Profile Using a Strain Gage Technique

A simple beam theory analysis is presented for the determination of residual stress patterns in beams or plates using a strain gage technique. The analysis is valid for a general stress distribution which need not be symmetric with respect to the neural axis. The experimental approach consists of attaching a strain gage on the surface of a beam or a plate and then grinding off the other side. The recorded strain vs thickness ground off data can be used to determine the corresponding stress profile.     

光密度法研究聚丙烯腈纤维的热稳定化过程

采用梯度升温曲线,在170～310℃内,每间隔10 min升高10℃对聚丙烯腈(PAN)纤维进行热处理,使用光密度法研究了PAN纤维的热稳定化。结果表明:PAN纤维在热稳定化过程中光密度发生了变化,热稳定化过程中纤维表面会发生反应生成致密的氧化层,导致皮芯结构的形成。光密度法是系统研究PAN纤维热稳定化程度与氧化均匀性的理想方法,具有良好的准确性灵敏性;引入了光密度标准差有效评估PAN纤维皮芯结构程度。     

基于分布式布里渊光纤散射传感的海底动力电缆监测技术研究

针对海底动力电缆出现故障而寻找电缆监测的技术与方法,分析渤海湾不稳定海域的海底动力电缆多次出现短路和断路故障的原因与机理,提出基于布里渊散射原理的分布式光纤传感技术监测电缆所受外力变化和监测电缆内部温度变化的方案和方法,进行三相高压电缆截面温度场和电缆外部受力变形的数值模拟分析,通过室内模拟实验和海堤沉降段电缆敷设后的光纤传感监测数据及水准仪观测监测数据对比分析,得出光纤传感器检测数据趋势与水准仪器测量结果吻合。模拟和现场测试结果表明,基于光纤布里渊散射原理的分布式光纤传感技术可有效实现海底动力电缆的温度和变形监测。     

Optical fiber multiparameter sensor for real-time monitoring of thermoplastic composites during in situ consolidation process

Temperature and strain are important parameters in the in situ consolidation process of thermoplastic composites and have been monitored based on optical fiber Bragg gratings. A special polyimide fiber grating (PFBG) is used in this article. PFBG can monitor temperatures up to 400°C and strains up to 40,000 με. The wavelengths of the PFBGs are obtained by wavelength demodulation system and fast digital signal processing with field programmable gate array. Temperature and strain in auto fiber placement process of thermoplastic composites are monitored accurately according to wavelengths. During the whole consolidation process, temperatures have been monitored with the accuracy of 0.1°C in the range of 100–250°C and strains have been monitored with the accuracy of 1 με in the range of ?250 to 500 με. The validity and correctness of the results have been validated by the thermocouple and the strain gauge.