用光纤布拉格光栅(FBG)监测焊接过程时需要对其进行金属化保护和增敏封装, 本文对其金属化增敏封装现状进行了总结, 对比了熔融涂镀法、真空蒸镀法、溅射法、化学镀、电镀金属化方法的优缺点。概括了FBG监测焊接过程时的传感信号和灵敏度的标定方法, 总结了耦合信号的分离方案。介绍了搅拌摩擦焊(FSW )、金属惰性气体 (MIG)焊、钨极惰性气体(TIG)焊等焊接过程的实时监测实例; 分析了各种实例中传感器的安装布局、保护增敏、选择参照仪器等技术环节。分析了FBG实时监测超声波焊、钎焊等焊接过程(接头和热影响区温度和应力应变演化)的可行性, 指出FBG应用于监测焊接过程时存在焊缝内部监测困难, 表面粘贴的FBG散热差, 容易引起监测失准、温度和应变交叉敏感等问题。

The optical Fiber Bragg Grating(FBG) should be metallized and its temperature sensitivity should be enhanced before it is used to monitor the metal welding. This paper gives the topics concerning the monitoring welding process using FBGs. Firstly, the status of the protection and sensitivity enhancement of FBGs is briefly summarized, and the merits and shortcomings of each method are compared on the melt coating, vacuum evaporation, sputtering, chemical plating and electroplating. Then, two important issues for the application of FBGs to the welding monitoring are analyzed, including, the calibration of sensing signals and their sensitivities as well the division of coupled sensing data. After that, the illustrations of the real-time monitoring welding processing using FBGs for temperature and strain are introduced, and the Friction Stir Welding( FSW), Metal Inert-Gas(MIG) welding and Tungsten Inert Gas (TIG) welding and some associated technological issues, as well the installation and layout of sensors, the protection and sensibilization of sensors and the reference sensor selection are systematically analyzed. In addition, the feasibility and application prospect of the FBGs in the monitoring ultrasonic welding and brazing are analyzed. Finally, it points out that the issues and difficulties in the real-time monitoring of welding process are monitoring the inside of welding joint, processing the data errors induced by the poor conduction between the pasted FBG and the weld surface, and the cross sensitivity of temperature and strain.