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针对经验模式分解(EMD)易受噪声影响的缺点,提出采用小波消噪结合Hilbert-Huang变换的结构损伤检测方法。首先对含噪声振动信号进行小波消噪预处理实现信噪分离,再进行EMD分解得到若干固有模态函数(IMF),利用希尔伯特(Hilbert)变换得到其瞬时频率。提出了一个基于低阶瞬时频率变化率的损伤判定指标,利用此指标可以判断损伤是否发生。数值研究结果表明小波消噪结合HHT的方法是进行损伤检测比较有效的方法。
In view of the disadvantage of empirical mode decomposition (EMD) being easily affected by noise, a structural damage detection method using wavelet denoising combined with Hilbert-Huang transform is proposed. First, noise-free signal is denoised by wavelet to achieve signal-to-noise separation, then EMD is decomposed to obtain several intrinsic mode functions (IMFs), and the instantaneous frequency is obtained by Hilbert transform. A damage detection index based on the rate of change of low-order instantaneous frequency is proposed. By using this index, the damage can be judged. Numerical results show that wavelet de-noising combined with HHT method is a more effective method for damage detection.