变分模态分解和同步挤压小波变换识别时变结构瞬时频率

Instantaneous frequency identification of time-varying structures using variational mode decomposition and synchrosqueezing wavelet transform

针对土木工程领域存在的时变多分量响应信号,提出一种变分模态分解定理和同步挤压小波变换理论相结合的时变结构响应信号瞬时频率识别新方法。该方法首先利用响应信号的小波量图判断分量信号的个数,然后通过变分模态分解定理将多分量信号自适应地分解为多个分量信号,最后对分解得到的分量信号进行同步挤压小波变换并识别其瞬时频率。通过一个多分量信号数值算例、一个质量突变悬臂梁试验和一个时变拉索试验验证该方法的有效性,研究结果表明:提出的新方法能够有效识别时变结构响应信号的瞬时频率,且识别效果优于传统的希尔伯特-黄变换和连续小波变换。

A combined method based on variational mode decomposition(VMD)and synchrosqueezing wavelet transform(SWT)was proposed to identify instantaneous frequencies from multi-component response signals of civil engineering structures.The wavelet scalogram was first introduced to estimate the number of the components contained in a response signal.Then,the VMD was used to decompose the response signal into several mono-components self-adaptively and the SWT was performed on the decomposed component signals to extract their instantaneous frequencies.A multi-component simulation,an aluminum cantilever beam test with abrupt mass reduction and a steel cable test with time-varying tension forces were used to verify the effectiveness and accuracy of the proposed method.The results demonstrated that the proposed method performs better than the traditional Hilbert-Huang transform and the continuous wavelet transform.