Shock and Vibration / 2019 / Article / Fig 4

Research Article

Free-Decay Nonlinear System Identification via Mass-Change Scheme

Figure 4

Time-frequency analysis of the 4-DOF system. (a) Spectrogram of the output no. 2. (b) Frequency variations of the four modes. Blue line: mode 1; orange line: mode 2; green line: mode 3; purple line: mode 4.

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