希尔伯特黄变换在调制超声激励-光纤光栅传感损伤检测中的应用

摘要

It is widely recognized that nonlinear ultrasonic method has more advantages than linear ultrasonic technology in micro defect detection.Vibro-ultrasonic modulation(VUM)method was adopted,and Fiber Bragg Grating (FBG)was used to sense nonlinear signal instead of piezoelectric patches because it is very easy for FBG to realize distributed measurement.The sensing characteristic of FBG for ultrasonic was studied and a VUM excitation-FBG sensing system for Aluminum thin plate was built.The Hilbert Huang transformation(HHT)was applied in the analysis of nonlinear signal,and it was proved that the nonlinear response was not only amplitude modulation(AM)signal but also frequency modulation(FM),so the influence of defect on amplitude and frequency should be considered in the further research.%相比于线性超声技术,非线性超声技术在微小损伤检测中的优势已得到广泛的认可.采用调制超声激励法,并利用布拉格光纤光栅(FBG)取代压电片实现调制超声响应的传感,使得整个系统更容易实现分布式检测.以铝制平板为对象,研究了FBG对超声的传感特性,建立了一个振动超声激励-FBG传感系统.利用希尔伯特黄变换对缺陷导致的非线性现象进行了分析,证实其既是调幅信号也是调频信号,因此在今后损伤分析研究中需同时考虑损伤对幅值和频率的影响.