光纤Bragg光栅在分离式Hopkinson压杆实验中的应用

Application of Fiber Bragg Grating in Split Hopkinson Pressure Bar Test

光纤Bragg光栅用于高频应变的测试是一个重要研究课题．文中介绍了其高频解调原理,探讨了光纤光栅传感器用于分离式霍布金逊压杆(SHPB)实验装置中应变测试的相关问题；推导了弹性杆中传播的应力波σ与传感光纤光栅中光波相位的变化量Δ(?)之间的关系式,进而建立了含有光纤光栅传感变化量的弹性杆应力波计算公式；构建了基于光纤Bragg光栅的动态应变测试系统,对中心波长分别为1550nm和1545nm的裸光纤光栅传感器以及应变片,两种传感器粘贴在被撞击弹性杆(输入杆)表面测试应变的情形进行了比较研究,给出了实验结果．研究表明,光纤Bragg光栅在高频动态应变测量中具有很好的应用潜力和前景,测试方法和结论对于光纤Bragg光栅在高频动态应变的实际测试中具有积极意义．

The principle of high-frequency demodulation for fiber Bragg grating （FBG） is introduced in the paper. The problems related to the application of FBG in split Hopkinson pressure bar （SHPB） for strain test are discussed. The relation between strain wave σ propagating in elastic bar and phase change △φ of FBG sensor is derived as well as the strain calculating formula for elastic bar. The dynamic strain acquisition system based on FBG is set up. Comparison of the detection of surface strain of FBG with center wavelength of 1 550 nm and traditional strain gage with center wavelength of 1 545 nm, The experimental results show that, for high frequency strain test, FBG sensor is more effective and has huge potentiality and application foreground. This method makes great sense to high frequency dynamic strain acquisition.