STUDY ON THE DISPERSION CHARACTERISTICS OF WOOD ACOUSTIC EMISSION SIGNAL BASED ON WAVELET DECOMPOSITION

Artificial AE sources were generated on the surfaces of Ulmus pumila, Zelkova schneideriana, Cunninghamia lanceolata, and Pinus sylvestris var.mongolicaLitv. specimens. The AE transverse wave signal was decomposed into 3-layers detail signalsby wavelet decomposition and reconstructed, and it was calculated based on correlation analysis. Then thelongitudinal wave speed was calculated according to the time-difference-of-arrival (TDOA) method, and the wood dispersion phenomenon was studied. The results showed that thedispersion phenomenon of Ulmus pumilawas obvious. The propagation speed of high-frequency signal was 2.38 times that of low-frequency signal. The ratio of high and low frequency propagation speed of soft wood was 1.72 and 1.73. The dispersion degree of Zelkova schneideriana was the weakest, and the propagation speed of the high frequency was 1.25 times of the low one. The ratios of longitudinal and transverse wave speedsof the four specimens were 4.59, 4.07, 4.24 and 4.2, respectively.