Based on the number of harmonic frequencies, and spectral derivative slit fence Rejecting Frequency Identification and

The present invention discloses a method based on the harmonic number of spectral derivative and frequency fence slit Frequency identification and culling method comprising the steps of: calculating a vibration signal power of a first derivative of the spectrum G (ω) or the second derivative, to obtain the spectrum mutation of ab (ω) or Dexterity ag (ω); setting spectrum mutation degrees or Dexterity thresholds are ab-max and ag-max; found ab (ωi) = ab-max or ag (ωi) = ag at the frequencies ωi -max; [omega] i after finding the first point of the frequency spectrum of mutations frequencies [omega] i is negative or after the third Dexterity negative frequencies ωj, ωj is the harmonic frequencies of the frequencies omega] H; harmonic recognized by construction frequencies ωh culling all harmonic frequencies slit fence frequencies, to obtain the true natural frequency of the mechanical structure. The method of detecting high accuracy, excellent in mechanical structure as the natural frequency in the operating state, the mechanical structure line identification and monitoring, identification of structural damage and provide a powerful means.