光纤光栅传感器阵列在撞击定位监测中的应用

Application of fiber Bragg grating sensor array in impact location monitoring

本文提出基于半导体环形激光器的光纤传感阵列系统,用于在铝板上撞击定位监测。采用光纤法布里-珀罗(F-P)标准具对光纤布拉格光栅(FBG)传感器信号进行解调。施加在FBG传感器的应变被编码为FBG反射光的波长位移,然后由自由光谱范围为50 GHz的光纤F-P标准具转换为强度调制。通过波分复用技术,光纤F-P标准具可同时解调多个FBG信号,光纤传感阵列系统安装在厚度为1 mm的铝板上,50 g的小钢球在20 cm的高度自由下落撞击铝板产生声发射信号。利用时频小波分析,从测量的FBG传感器瞬态响应中获得的Lamb波的群速度频散曲线,并根据三角定位算法,确定撞击点的坐标。经过撞击试验,通过本系统和定位算法的平均定位精度误差在30.89 mm,达到了较好的精度。

In this article, an optical fiber sensing array system based on semiconductor ring laser is proposed for impact location monitoring on aluminum plate. A fiber Fabry-Perot etalon is used to demodulate the signal of fiber Bragg grating sensor(FBG). The strain applied to the FBG is encoded as the wavelength shift of the reflected light of the FBG sensor. Then, it is converted into intensity modulation by the optic Fabry-Perot etalon with a FSR of 50 GHz. The optic F-P etalon can demodulate multiple FBG signals at the same time via wavelength division multiplexing. The optical fiber sensing array system is installed on an aluminum plate with a thickness of 1 mm. A 50 g small steel ball falls freely at a height of 20 cm and strikes the aluminum plate to generate acoustic emission signals. By using time-frequency wavelet analysis, the group velocity dispersion curve of Lamb wave is obtained from the measured transient response of the FBG sensor, and the coordinates of the impact point are determined according to the triangular positioning algorithm. Through the impact test, the average positioning accuracy error of the system and positioning algorithm is 30.89 mm, which achieves good accuracy.