运用统计小波的光纤光栅结构健康监测技术

针对振动型结构健康监测方法的特点,搭建了基于非平衡M-Z干涉仪和相位载波解调技术的光纤光栅损伤识别系统。运用小波包分解振动信号,建立了基于小波包节点能量相对变化率之和的结构损伤识别指标;介绍了统计过程控制原理,推导了使用均值-极差控制图分析损伤识别指标,识别结构连续损伤的过程。实验测试了铝制简支梁结构处于健康状态和3种损伤状态下的各40次振动信号。信号时域图显示各状态振动信号持续时间均约为0.05ms,幅值基本相同。依据结构健康状态下的统计过程控制限(12.85,41.35)进行了均值-极差控制图损伤识别分析,结果表明,搭建的损伤识别系统能连续地对结构进行健康监测。

Structural health monitoring technology with fiber Bragg grating using statistical wavelet-based method

The interrogation system based on a Fiber Bragg Grating sensor was designed for damage identification by using a unbalanced M-Z interferometer and a Phase-Generated-Carrier (PGC) technology according to the features of vibration type Structural Health Monitoring (SHM) method. The damage indicator,namely the sum of relative variation ratio, was constructed based on the wavelet packet node energy of vibration signals. Then,the control principle of statistical process was introduced and the index of damage identification was derived by using X-R statistical process control. The 160 vibration signals of an aluminum simply supported beam under a health state and three kinds of damage states were measured using FBG interrogation,and results show that the duration of time domain vibration signal in each state is approximately 0.05 ms and their amplitudes are basically the same. The damage identification was analyzed based on the statistical process control limit (12.85, 41.35) ,and it is concluded that the damage identification system is good at continuously structural health monitoring.