基于光纤光栅的PBX声发射监测方法

为解决传统压电传感器(piezoelectric,PZT)不能植入弹药内部监测高聚物粘结炸药(polymer bonded explosives,PBX)损伤问题,利用可调谐窄带光源搭建了基于光纤布拉格光栅(fiber Bragg grating,FBG)微细传感器的PBX声发射监测系统(FBG-AE),开展了PBX单轴拉伸、压缩及断铅实验,对比了FBG与PZT两种传感器的信号特征;同时还开展了FBG方法的环境适应性、信号方向敏感性等研究,以验证该监测系统的基本性能。研究结果表明:虽然试验中FBG信号幅值略低于PZT,但也能产生毫伏级以上输出信号,可以应用于PBX损伤在线监测;在环境温度与变形场分别小于±3℃或±25με范围内时,该FBG-AE系统能够有效监测到PBX上产生的断铅信号;FBG对AE信号方向具有敏感性,在90°和270°方向(即垂直于FBG轴向方向)信号幅值最低,提出并验证了采用弯曲粘贴FBG方法可以减小声发射监测方向敏感性差异,有利于提高PBX损伤定位精度。

Acoustic Emission Monitoring Method of Fiber Bragg Grating in PBX

In order to solve the problem that the traditional piezoelectric(PZT)sensor can not be implanted into the ammunition to monitor the polymer bonded explosives(PBX)damage,a PBX acoustic emission monitoring system based on the micro-sensor of the fiber Bragg grating(FBG)was constructed by using a tunable narrowband laser source.The uniaxial tension,compression and pencil lead break experiments of the PBX materials were carried out,and the signal characteristics monitored by the FBG and PZT sensors were compared.At the same time,the environmental adaptability and signal direction sensitivity of the FBG method were also studied to verify the basic performance of the monitoring system.The results show that:although the amplitude of the signal monitored by FBG in the test is slightly lower than the PZT,it can also generate output signal above the millivolt level,which can be applied to online monitoring of PBX damage;When the ambient temperature and strain field are less than±3℃or±25με,respectively,the FBG-AE system can effectively monitor the AE signal generated by PBX damage;FBG is sensitive to the direction of AE signal,and the signal amplitude is the lowest in the 90°and 270°directions(the direction of perpendicular to the FBG axial).It is proposed and verified that the gluing method of bending FBG can reduce the difference in the sensitivity of the FBG in response to AE signal,which is beneficial to improve the positioning accuracy of the acoustic emission source.