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

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. © 2018, Editorial Office of Journal of Vibration and Shock. All right reserved.