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提出了调频EMD方法,克服了原EMD方法在密集频率情况下容易产生固有模式函数(Intrinsic Mode Function,IMF)混淆的弱点,可以较好地分解相对密集频率的弱非线性信号,得到物理意义相对明确的IMF。与Hilbert-Huang变换相结合,有效地识别多自由度弱非线性系统瞬时模态信息的变化过程。通过数值仿真计算证明了调频EMD方法的有效性。利用调频EMD方法对Humber大桥的主梁两自由度节段模型自由气弹振动信号进行识别,揭示了该耦合系统的非线性。
The EMD method is proposed, which overcomes the weakness of the original EMD method in confusing the Intrinsic Mode Function (IMF) under the condition of dense frequency, and can decompose the weak nonlinear signal of relatively dense frequency well, and obtain the relative physical meaning Clear IMF. Combined with Hilbert-Huang transform, the change of instantaneous modal information in multi-degree-of-freedom weakly nonlinear system can be effectively identified. The effectiveness of FM EMD method is proved by numerical simulation. Frequency modulation EMD method is used to identify the free air-to-air missile vibration signals of the two-degree-of-freedom joint model of Humber Bridge. The nonlinearity of the coupled system is revealed.