变分模态分解和小波等值线法识别结构瞬时频率  

Recognition of Instantaneous Frequency of Structures by Variational Modal Decomposition andWavelet Isoline Method

作　　者：刘文 蒋淑霞[1] 王天鹏 柳霞 何泽江 LIU Wen;JIANG Shuxia;WANG Tianpeng;LIU Xia;HE Zejiang(School of Mechanical and Electrical Engineering,Central South University of Forestry and Technology,Changsha 410004,China;School of Civil Engineering,Central South University of Forestry and Technology,Changsha 410004,China)

机构地区：[1]中南林业科技大学机电工程学院,长沙410004 [2]中南林业科技大学土木工程学院,长沙410004

出　　处：《噪声与振动控制》2023年第5期167-174,226,共9页Noise and Vibration Control

基　　金：湖南省自然科学基金资助项目(2019JJ60076);湖南省交通运输厅科学研究资助项目(201527)。

摘　　要：针对土木工程结构多分量时变模态参数识别困难问题,提出一种基于变分模态分解(Variational Modal Decomposition,VMD)、小波分析和等值线法相结合的瞬时频率识别新方法。首先,通过连续小波变换确定模态分量个数,利用VMD分解多分量信号得到各模态分量;然后,采用小波分析和等值线法识别每个模态分量的瞬时频率;最后,叠加展示各模态分量的时频曲线。为解决长时段信号小波能量衰变问题,提出一种等间距拆分时段、逐段分析的方法。采用多分量时变数值算例验证该方法的有效性和准确性。设计一个具有时变刚度拉索结构试验,对线性和正弦两种时变工况下索的振动位移响应数据进行分析,从而识别出拉索的时频变化曲线。结果表明,提出的方法可以准确有效地识别出多模态时变结构的瞬时频率,其拆时段分析手段在组合的可视化展示中有很好的时频效果,该方法具有较强的抗噪性和时频特征提取的稳定性。In view of the difficulty of identifying the multi-component time-varying modal parameters of civil engineering structures,a new instantaneous frequency identification method based on the combination of variational modal decomposition(VMD),wavelet analysis and isoline method is proposed.Firstly,the number of modal components is determined by continuous wavelet transform,and the modal components are obtained by VMD decomposition of multi-component signals.Then,wavelet analysis and isoline method are used to identify the instantaneous frequency of each modal component.Finally,the time-frequency curves of each modal component are superimposed.In order to solve the problem of wavelet energy decay of long-time signal,an equal-spacing time split analysis method is proposed.The validity and accuracy of the proposed method are verified by multi-component time-varying numerical example.A time-varying stiffness cable structure test is designed to analyze the cable vibration displacement response data under linear and sinusoidal time-varying conditions.Thereby,the time-frequency curve of the cable is identified.The results show that the proposed method can identify the instantaneous frequency of multi-mode time-varying structures accurately and effectively,and the time split analysis method has a good time-frequency effect in the composite visual display,and the method has strong anti-noise performance and extraction stability of time-frequency features.

关 键 词：振动与波 时变结构 瞬时频率 变分模态分解 连续小波变换 等值线法 

分 类 号：TN911.6[电子电信—通信与信息系统] TU311.3[电子电信—信息与通信工程]