光纤传感器灵敏度与探头机械性能关系的研究.pdf

上海交通大学硕士学位论文光纤传感器灵敏度与探头机械性能关系的研究姓名：余飞申请学位级别：硕士专业：电磁场与微波技术指导教师：李新碗20070201上海交通大学硕士学位论文上海交通大学硕士学位论文: 光纤传感器灵敏度与探头机械性能关系的研究光纤传感器灵敏度与探头机械性能关系的研究 II 模型，推导了应变灵敏度的理论公式，同时采用有限元法分析了光纤光栅放置点对基于圆环梁的光纤光栅应变传感器灵敏度的影响，并得到了实验验证结果显示：在采用圆环梁的结构中，在施力点沿逆时针转动，00~047之间00处灵敏度最大，之后灵敏度按余弦函数规律逐渐减小，到047附近灵敏度降为零；047~090之间灵敏度又按照余弦函数规律逐渐增大，090处灵敏度达到最大 3. 对封装的光纤光栅应变传感器， 理论推导了增敏公式， 同时采用有限元方法分析了不同封装结构对其应变灵敏度的影响，结果表明：为提高封装增敏效果，应选用弹性模量尽量小的封装材料，而且采用多层封装结构（内层为弹性模量较小且粘结性强的聚合物材料，外层为弹性模量较大的聚合物材料）的增敏效果明显优于单层封装结构此结论得到了实验验证 关键词：干涉型光纤磁传感器，FBG 应变传感器，灵敏度，有限元分 析，探头，机械性能 上海交通大学硕士学位论文上海交通大学硕士学位论文: 光纤传感器灵敏度与探头机械性能关系的研究光纤传感器灵敏度与探头机械性能关系的研究 III STUDY ON RELATIONSHIP BETWEEN SENSITIVITY AND MECHANICAL PERFORMANCE OF OPTICAL FIBER SENSOR ABSTRACT Compared with mechanical and electronic sensor, the fiber-optic sensor has had great development with its high sensitivity, large dynamic range, convenience, compactness and so on. Interferometric fiber-optic weak magnetic sensor and fiber grating strain sensor have become the hot topics in the field of research on the fiber-optic sensor technologies. The study target of this dissertation is to analyze the relationships between system sensitivity and mechanical parameters of transducer for the two kinds of sensors mentioned above. The main contents include: Firstly, the interferometric fiber-optic weak magnetic sensor was introduced. A mathematical model was presented to analyze the mechanical performance of the transducer for fiber-optic weak magnetic field sensors using finite element method. The resonant frequencies from the lowest mode up to the fortieth order mode were calculated. It was found that the transducer has the highest sensitivity at the 32nd order resonant frequency, which agrees with the experimental result. This indicates the validity of the model. It provides an effective method for the optimal design and implementation of the transducer, and the system sensitivity can be improved accordingly. The displacements of transducer with different sizes of magnetostrictive rings and different lengths of fiber wrapped on the ring were calculated through harmonic response analysis. The results are that maximum displacement of sensing transducer can be 上海交通大学硕士学位论文上海交通大学硕士学位论文: 光纤传感器灵敏度与探头机械性能关系的研究光纤传感器灵敏度与探头机械性能关系的研究 IV achieved to improve system sensitivity by largening outer radius or width of the ring or lengthening the fiber. Secondly, a kind of FBG (Fiber Bragg Grating) strain sensor based on semi-circular ring structure is analyzed. The mechanical displacement model of semi-circular ring was built up and theoretical formula was put forward. Influence of position of FBG on system sensitivity was analyzed by FEM (Finite Element Method) and the result which was validated by experiment shows that the sensitivity decreases from the maximum to zero for 00to 047counter-clockwise from the force point, and increases from zero to the maximum for 047to 090according to the rule of cosine function. At last, a theoretical derivation was made for enhancing strain sensitivity of package structure-based FBG strain sensor. The strain sensitivity of FBG sensors with three different package structures were analyzed by FEM. Conclusion is that the sensitivity increases with decrease of elastic modulus of package material and the sensitivity of multi-layer package (inner layer is polymer with smaller elastic modulus as well as strong adhesive capacity and outer layer is polymer with larger elastic modulus) is higher than that of single layer package. The above conclusion was validated by experiment. KEY WORDS：：Interferometric Fiber-optic Magnetic Sensor, FBG Strain Sensor, Sensitivity, FEM, Transducer, Mechanical Performance 上海交通大学硕士学位论文上海交通大学硕士学位论文: 光纤传感器灵敏度与探头机械性能关系的研究光纤传感器灵敏度与探头机械性能关系的研究 1 1 绪论 1.1 传感技术概述 传感器的基本作用是将某种形式的输入(被测对象)的变化转换为同种或其它形式的信号的单值变化。

今天的世界， 科学技术迅猛发展， 人类社会已步入信息时代，社会活动越来越离不开信息的采集，传输和处理传感器技术是关于传感器原理、设计、制造及应用的综合技术，它在测量系统中占有十分重要的地位，能否获得信息和获得的信息是否正确，关系到整个测量或控制系统的成败与精度 现代信息技术的三大基础是信息的拾取、传输和处理，也就是传感技术、通信技术和计算机技术，三者的发展是紧密结合，互相促进的，当代计算机技术的飞速发展也促进了传统的传感器的新发展近年来，传感器技术越来越为世界各国所认识并重视起来，世界上许多国家都已经在努力研究各种新型传感器，改进传统的传感器，开发各种新型传感器，这已经成为当前科学技术的主要课题之一[1]在过去的 20 世纪里，西欧各国争相把传感器技术列为本国国防科技发展的重点技术；美国曾把传感器技术评为其在 90 年代发明的 22 项关键技术之一；日本也把传感器技术列入影响其未来发展的六大核心技术(计算机、半导体、通信、激光、超导和传感器技术)之一美国和欧洲传感器市场投资总值的年增长率为 32%，英国传感器销售额 1990 年比 1980 年增长 24 倍[2,3]到了如今 21 世纪，各方面对传感器的需要也越来越强烈，预计于 2010 年将形成超过 50 亿美元市场的产业。

中国传感器的市场上海交通大学硕士学位论文上海交通大学硕士学位论文: 光纤传感器灵敏度与探头机械性能关系的研究光纤传感器灵敏度与探头机械性能关系的研究 2 近几年一直保持平稳的增长态势，2003 年中国传感器的市场销售额为 186 亿元，同比增长 32.9%预计 2007 年传感器国内市场容量为 8.5~10.5 亿只，年产量(推荐量)为 13.4~16.8 亿只考虑到产品出口量，则 2007 年我国将建成年生产能力达到 20亿只的传感器新兴产业但是我国目前生产的传感器，无论在品种、数量和质量上都远远满足不了市场的需求[4]所以，目前国内很多高校及企业的科学研究工作者都在进行这方面的研究 1.2 光纤传感技术及其发展状况 光纤传感技术是以光波为载体，光纤为媒质，感知和传输外界被测量信号的新型传感技术，是 20 世纪 70 年代伴随光纤通信技术的发展而迅速发展起来的光纤通信拥有一个广阔的市场，能提供一系列低价格的器件，更重要的是，它形成一门光纤传感器技术所适用的基础科学1970 年，美国康宁公司成功研制出传输损耗为20dB/km 的光导纤维，同年该公司又成功地使得操作简便的砷化铝钾(GaAlAs)半导体激光器在室温下连续运行，这两项发明为现代光通信的实用化。