Wavelet packet analysis for acoustic emission signals caused by debris cloud impact

The feature of energy distribution of acoustic emission signals caused by debris cloud impact of an aluminum alloy plate was investigated based on the wavelet packet method. Firstly, the process to obtain the signals and the damage caused by debris cloud impact were introduced. Secondly, the signals were analyzed by using wavelet packet, and the change of energy distribution in different frequency bands was obtained. Finally, the relationship between debris cloud impact damage characteristics and acoustic emission signals energy distribution was discussed. The results showed that for the same mass of projectiles, the more completely they are broken, the less damage on the plate the debris cloud leads to; with higher initial speed, the projectiles are broken more completely, the signals caused by debris cloud impact have less energy; when the projectiles are not completely broken, the acoustic emission signal energy is concentrated within the range of less than 488 kHz; the energy proportion of the signal above 488 kHz increases as the projectiles are broken more completely.