Research On Micro-damage Identification Method Of Metallic Plate Based On Wavelet Packet Energy Spectrum

Based on the analysis technology of wavelet packet energy spectrum, the problem of micro damage and its degree detection in piezoelectric intelligent plate structure is studied in this paper. Numerical simulation is used to simulate the response signal of the structure containing micro damage with its degree changes. The response signal is decomposed by wavelet packet analysis to get a series of sub-signals and energy spectrums accordingly. The relationship between the distribution of energy spectrum and the kind and degree of damage is researched to guide testing work.The spectral finite element model of the intelligent metal plate structure combined with piezoelectric material is established on the base of Mindlin plate theory. The dynamic signal of this model is approached by numerical simulation when the structure contains micro groove damage and void damage with very little changes in their degree.Using wavelet packet analysis technology to decompose the dynamic signal of the structure to get a series of sub-signals with their energy spectrums and comparing the energy spectrums between the complete structure and the damaged, the rate of change in the energy spectrum is researched to get the influence witch the damage brings to it and the relationship between them.Results show that the energy spectrum of the response signal possesses much more sensitivity in early damage detection compared with other methods. Not only can the micro groove damage and void damage in the structure be detected, but also their degree can recognized very well. The numerical spectral finite element model of the piezoelectric intelligent plate structure and the damage identify method based on wavelet packet energy spectrum established in this paper can provide important theoretical guidance for detecting and evaluating the kind and degree of micro-damage in real work.