环形腔全光纤F-P干涉仪的声发射检测

Ring cavity all fiber F-P interferometer used in detection of acoustic emission

为了实现固体材料内部声发射信号的检测,提出了一种新型结构的全光纤F-P干涉仪。将2×2光纤耦合器的一个入射端与一个出射端焊接相连,以其代替传统的反射腔面,构成光纤环形传输腔,腔体贴附或埋入待测固体中检测声发射信号。通过理论推导和计算机仿真,确定了此结构光纤传感器的检测特性。实验以大理石板作为待测介质,对利用信号发生器驱动压电陶瓷(PZT)作已知声发射源在大理石板中产生的连续型声发射信号,及冲击波作用下大理石板中产生的突发型声发射信号进行了检测,并利用Fourier变换得到了声发射信号的特征频率。实验结果表明,此种结构传感器能够检测材料结构中使光纤轴向伸缩长度达10-8m量级的声发射信号并识别其特征频率。该结构光纤传感器无需光程的匹配,适用于大尺度构件的监测,是材料结构健康检测与监控的一种新方法。

In order to detect the Acoustic Emission（AE） signals in solid materials, a novel ring cavity all fiber F-P interferometer is proposed. By welding the incidence and the exit of a 2 × 2 optical fiber coupler directly, an optical fiber ring cavity is constructed,which can be attached or embedded in the measured solid to detect the AE signals. The detection property of the optical fiber sensor is determined through the theoretical derivation and the computer simulation. Otherwise, a piezoelectric ceramic（PZT） is powered by signal generator to generate a continuous known AE signal, and a blast wave is adopted to simulate the burst AE signal in marble slabs. Then, they are detected by the optical fiber sensor, and the characteristic frequencies of AE signals are obtained by the Fourier technique. Experimental results indicate that the system can detect AE signals that cause the optical fiber stretching to 10 8 m in an axial direction and can identify the characteristic frequency of AEs. For it can work without the match Of optical path and is suitable for monitoring the large scale component, the sensor provides a new method for the health examination and the monitoring of material structures.