Time-varying cross mode identification method based on nonlinear frequency modulation mode decomposition

The invention belongs to the technical field of civil engineering structure health monitoring data analysis, and relates to a time-varying cross mode identification method based on nonlinear frequency modulation mode decomposition. The method comprises the following steps: firstly, calculating time-frequency distribution of collected acceleration response by adopting short-time Fourier transform, and extracting a ridge line of the time-frequency distribution; secondly, calculating time vibration mode coefficients under different frequencies by using the time-frequency distribution of the positions of the sensors; then, calculating a time vibration mode correlation coefficient at a ridge line time frequency point, and determining an initial center frequency of a cross mode in combination with a ridge line frequency; and finally, extracting the instantaneous frequency of the cross mode through a nonlinear frequency modulation mode decomposition method. According to the method, the initial center frequency is de