【作者】 李英；

【导师】 李维来；

【作者基本信息】 武汉理工大学 ， 机械电子工程， 2006， 硕士

【摘要】 光纤布喇格光栅(Fiber Bragg Grating,FBG)是目前最有发展前途、最具代表性的光纤无源器件之一。由于它能将被感测信息,如温度和应力的信号,转化为反射波长的偏移,即具有波长编码的特性,因而不受光源功率波动和系统损耗的影响。另外,光纤光栅具有可靠性好、抗电磁干扰、抗腐蚀等优点,易于将多个光纤光栅串联在一根光纤上构成光纤光栅阵列,实现分布式传感,这是其他传感元件无法比拟的。这种传感器在大型结构(如水坝、桥梁、重要建筑和飞行器、舰艇等)和特殊场合(如矿井、油田等的压力容器或压力管道)的安全监测方面具有广泛的应用前景,特别是其现场无电信号因而本质防爆的特点,近年来FBG传感器已经越来越引起人们的重视。 本文的内容是压力容器或压力管道的表面应力测量。以FBG为对象,以理论应变值为真值,对比传统的电阻应变片的测量值,进行研究和分析。 首先对FBG的应变传感特性进行了实验和研究。用光纤光栅本身吊重物,定量研究了FBG的Bragg波长和应变之间的线性关系,即标定了FBG的特性。 其次推导出该压力容器表面圆周向(横向)和轴向应变的理论值曲线。 在容器表面粘贴了8个波分复用的FBG来监测加载后容器的轴向和横向应力,同时在每个测量光栅的旁边各贴上一个电阻应变片,作为对比。分析了FBG和电应变片两种方法的应力测量结果,并与理论值进行对比。 考虑到由于光纤轴向受拉会变细,影响应变测量的结果,因此对受拉应力的光栅,使用了补偿的办法。 在复杂应力条件下,采用简化的方法,使之变成纯拉应力。并对比分析了受复杂应力的FBG与同一受力情况下采用简化受力方式的FBG的应变差别。 可以得到以下结论: 1.在轴向应变上:以理论值为真值,FBG的测量值比应变片测量值精确6%。 2.在横向应变上:以理论值为真值,FBG的测量值与应变片测量值相当,精度提高1%。更多还原

【Abstract】 At present, Fiber Bragg Grating (FBG) is one of the most potential and typical optical passive components. FBG can be immune from disturbance of light source and system attenuation, because it transforms sensing information, strain and temperature for instance, into reflecting wavelength shift, which is of the characteristic of wavelength coding. Besides, FBG is of good characteristic such as good reliability, immune from fire, electromagnetic interference and corruption. It can also be constructed as an FBG network in series to realize distributed sensing by Wavelength Division Multiplex (WDM), which is impossible for traditional sensors. FBG sensor therefore has wide prospect in use in huge constructions and dangerous situations, such as the dam, building, bridge etc, especially the compressive container or pipe in oil field and mine. That is way the research and application of FBG attract more and more attention in recent years.This thesis focuses on the strain measurement on the surface of compressive container or pipe, and compared the results of FBG and traditional resistance foil strain gauges (RFSG) with theoretical strain value.This thesis first studied the characters of FBG strain sensor. By hanging weights, it researched the linear relations in quantity between Bragg wavelength and strain that is to calibrate the characters of FBG strain sensor.Secondly, the theoretical strain value of this loaded contain both in hoop and in axis is calculated.There were eight FBGs in a way of WDM to detect respectively hoop and axis strain on the surface of a hydrostatically loaded container. Nearby each FBG, there is a RFSG as a reference. Then, the responses were analyzed and compared with theoretical strain value.Considering the fiber getting thin when it is pulled, it affects the response. So a compensation measure is employed.Finally, a simplification FBG encapsulating method is used to change the complex stress into pure tensile stress, and to compare the strain response with the response from the un-simplified encapsulating FBGWe have drawn the following conclusions:1. In axis direction, taking theoretical strain value as true strain value, FBG was 6% closer than RFSG2. In hoop direction, taking theoretical strain value as true strain value, FBG was approximately the same with RFSG as 1% error.3. The strain responses of compensated tension FBG were closer to the theoretical strain value than before compensation.4. The strain responses from simplified encapsulating FBG were closer to the theory than the un-simplified encapsulating FBGThus, because the FBG is of high precision, repeatability, linearity, and sensibility, it is good for strain measurement of compressive container or pipe, in hoop or in axis directions. Introduced in this thesis, the research of compensation of tensioning FBG, and the research of simplified encapsulation of FBG, can promote the engineering application of FBG更多还原