光纤传感器激光焊接封装及其热压传感特性

发布时间：2018-06-06 11:36

本文选题：光纤布喇格光栅 + 温度灵敏度　；参考：《南昌大学》2017年硕士论文

【摘要】：光纤布喇格光栅(Fibet Bragg grating,FBG)具有径细、质量轻以及集信息传输与传感于一体等优良特性,是智能结构首选的信息传输与传感的载体,也是智能金属结构采用的传感元件之一,广泛应用在各个工程领域中。光纤本身质脆,纤细的石英光纤抗弯强度差,特别是写入光栅后变得更易损坏,因此埋入金属基体之前,需要对其进行有效的保护。文章研究了激光焊接封装光纤光栅涉及到的光栅保护、宿主金属焊接试验、激光焊接封装过程以及焊接封装以后的传感特性等问题。主要内容如下:1)FBG封装保护。采用化学镀结合电镀的方法对FBG进行金属化,实验结果显示:FBG化学镀Ni,Cu层表面均光滑,连续,镀层均匀致密,没有明显的开裂和起皮等缺陷;表面化学镀Ni后电镀Ni,电镀Zn的FBG表面均平滑,光亮,没有明显的凸起颗粒,表层无裂纹。说明采用化学镀结合电镀的方法可以对FBG进行良好的金属化保护。2)金属化FBG的热压传感性能测试。结果显示:化学镀Ni电镀Ni和化学镀Ni电镀Zn金属化FBG中心波长随温度变化而发生线性变化,温度灵敏度分别为:20.23 pm/℃和34.36 pm/℃,分别是裸FBG温度灵敏度的2.04倍和3.55倍。镀Zn金属化FBG对瞬态温度变化响应趋势与裸FBG类似,这可能归因于镀层金属的热容量小,镀层厚度较薄。化学镀Ni结合电镀Ni和化学镀Ni结合电镀Zn金属化FBG中心波长与负载呈线性变化趋势,且应变灵敏度分别为:4.98pm/g和5.12pm/g。镀Zn金属化FBG的中心波长比裸FBG的稳定性稍低,中心波长偏差值分别为0.013nm和0.008nm,产生这种现象的原因可能为镀Zn金属化FBG具有较高的温度灵敏度。3)化学镀膜过程中本征应力演化的实时监测。提出基于光纤传感的化学镀膜过程中本征应力的计算模型,并对化学镀Cu和化学镀Ni过程中产生的本征应力进行了实时监测。实验结果显示:化学镀Cu过程中FBG中心波长发生蓝移,薄膜在生长过程中对监测光栅施加压应力,三次镀Cu实验中,产生的本征应力分别为:17.80Mpa、23.65Mpa和28.04Mpa;化学镀Ni实验结果显示:化学镀Ni试验中,监测光栅中心波长发生红移,累积应力表现为拉应力,整个化学镀Ni过程中产生的本征应力为12.92MPa。采用基于光纤传感的本征应力监测方法时传感器的应力灵敏度可以达到4.10 pm/MPa,准确度可达到0.24MPa。4)金属化FBG激光焊接封装。将金属化FBG激光焊接封装在银铜薄箔表面,制成传感头,分析了FBG在焊接封装后的热压传感特性。实验结果显示:金属化FBG和银铜共晶合金结合良好,焊缝较窄且连续,均匀细致。焊接封装FBG温度灵敏度为16.94 pm/℃,是裸FBG温度灵敏度的1.76倍。FBG中心波长与载荷呈线性变化趋势,焊接封装FBG的应变灵敏度为0.197 pm/g。研究了激光焊接过程中残余应力的产生对焊接封装FBG中心波长的稳定性,实验结果显示:在常温下,激光焊接封装FBG比裸FBG的稳定性稍差,在整个稳定性实验时间段内激光焊接封装的FBG和裸FBG中心波长的偏差分别为0.091nm和0.006nm,产生这种现象的原因可能为FBG在焊接封装过程中银铜共晶合金发生变形致使整个FBG传感器结构有残余应力,影响FBG中心波长的稳定性,此外,较高的温度灵敏度也影响着整个焊接封装FBG传感器中心波长的稳定性能。
[Abstract]:Fibet Bragg grating (FBG) has fine characteristics such as fine diameter, light mass, and integrated information transmission and sensing. It is the preferred carrier of information transmission and sensing in intelligent structure, and also one of the sensing elements used in intelligent metal structure. It is widely used in various engineering fields. Fiber itself is brittle and fine. The flexural strength of the British fiber is poor, especially when it is written into the grating, which is more easily damaged, so it is necessary to protect it effectively before embedding the metal matrix. The paper studies the grating protection, the host metal welding test, the sealing process of the laser welding and the sensing characteristics after the welding package. The main contents are as follows: 1) FBG encapsulation protection. FBG is metallized by electroless plating and electroplating. The experimental results show that FBG is electroless Ni, the surface of Cu layer is smooth and continuous, the coating is uniform and compact, there is no obvious cracking and peeling defects; the surface of the surface is electroless Ni plating Ni, the FBG surface of the electroplated Zn is smooth, bright, and no obvious. There is no crack in the surface of the convex particles. It shows that the method of electroless plating combined with electroplating can make a good metallization of FBG.2) the thermal pressure sensing performance test of the metallized FBG. The results show that the central wavelength of the electroless Ni electroplating Ni and the electroless Ni electroplating Zn metallized FBG center wavelength changes linearly with the temperature change, and the temperature sensitivity is respectively: 20.23 pm/ C and 34.36 pm/ C are 2.04 times and 3.55 times of bare FBG temperature sensitivity respectively. The response trend of Zn metallized FBG to transient temperature is similar to bare FBG, which may be attributed to the small thermal capacity of the plated metal and thin coating thickness. The electroless plating Ni combined with electroplating Ni and electroless plating Ni combined electroplating Zn metallized FBG center wavelength and load present The linear variation trend and strain sensitivity are as follows: the central wavelength of 4.98pm/g and 5.12pm/g. plated Zn metallized FBG is slightly lower than that of naked FBG, and the central wavelength deviation values are 0.013nm and 0.008nm, respectively. The cause of this phenomenon may be the intrinsic stress in the electroless plating process of the Zn metallized FBG with a higher temperature sensitivity.3). A calculation model of intrinsic stress in the process of electroless plating based on optical fiber sensing is proposed. The intrinsic stress produced in the electroless Cu and Ni electroless plating process is monitored in real time. The experimental results show that the FBG center wavelength is blue shift during the electroless plating of Cu, and the thin film exerts pressure stress on the monitoring grating during the process of growth. The intrinsic stresses produced in the three Cu experiments were 17.80Mpa, 23.65Mpa and 28.04Mpa, respectively. The results of electroless plating Ni showed that in the electroless plating Ni test, the central wavelength of the grating was red shift and the cumulative stress was expressed as tensile stress. The intrinsic stress produced in the whole electroless plating Ni process was based on the intrinsic stress based on optical fiber sensing for 12.92MPa.. The stress sensitivity of the sensor can reach 4.10 pm/MPa and the accuracy can reach 0.24MPa.4) metallized FBG laser welding package. The metal FBG laser welding is packaged on the surface of silver and copper foil to make a sensor head. The thermal pressure sensing characteristics of FBG after the welding are analyzed. The experimental results show that the co crystallization of the metal FBG and the silver copper alloy. The weld seam is relatively narrow and continuous and uniform and meticulous. The temperature sensitivity of the welded package FBG is 16.94 pm/ C, it is 1.76 times the temperature sensitivity of the bare FBG, the center wavelength of.FBG is linearly changing, the strain sensitivity of the welding package FBG is 0.197 pm/g., and the residual stress in the laser welding process is studied in the welding package FBG. The experimental results show that the stability of the laser welded package FBG is slightly worse than the naked FBG at normal temperature. The deviation of the laser welded FBG and the naked FBG center wavelength is 0.091nm and 0.006nm respectively during the whole time period of the stability experiment. The original cause of this phenomenon may be the Silver Copper Co crystallization in the welding process of the FBG. The deformation of gold causes the residual stress in the structure of the whole FBG sensor, which affects the stability of the FBG center wavelength. In addition, the high temperature sensitivity also affects the stability of the central wavelength of the entire welding package FBG sensor.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG456.7;TP212

【参考文献】