WOOD RESEARCH Volume 68, Number 1, 2023
Saiyin Fang, Ming Li, Wei Li, Chang Lin Huang, Tingting Deng, and Kun Du

Experimental analysis of acoustic emission propagation velocities and energy attenuation law of p and s waves in wood using improved TDOA measurements

To explore the propagation law of AE signal in wood, the propagation velocity of P-wave and S-wave and the energy attenuation law of different frequency components were studied By PLB (pencil-lead break) tests. Firstly, an improved time-difference-of-arrival (TDOA) method was designed to determine the arrive time. The propagation velocities of P-wave and S-wave were calculated. Then, the Young’s modulus was estimated by P-wave velocity. Finally, on the basis of eliminating the influence of standing wave, the energy attenuation models were obtained by numerical fitting and wavelet decomposition. The results showed that the improved TDOA algorithm can calculate the propagation velocity of P-wave and S-wave at the same time through one test, and the P-wave velocity can be used to estimate the Young’s modulus. P-wave propagated faster in soft wood, while S-wave propagated faster in hard wood. The higher the frequency of AE signal, the faster the energy attenuation.

WOOD RESEARCH Volume 67, Number 4, 2022
Saiyin Fang, Ming Li, Tingting Deng, and Kun Du

Study on the time-frequency characteristics and propagation law of acoustic emission longitudinal waves in wood grain direction

To study the propagation law of acoustic emission (AE) longitudinal waves in wood, the relationship among wave velocity, standing wave fundamental frequency and Young’s modulus of elasticity was studied, and the energy decay model of AE longitudinal waves along the grain direction was established. Firstly, the propagation velocity of the longitudinal wave was calculated using the time-difference method. Then, the relationship between the wave velocity and Young’s modulus of elasticity was analyzed and the method of calculating the longitudinal wave velocity using the fundamental frequency was proposed. Finally, using different levels’ pulse strings as AE sources, the attenuation law of AE signal energy with distance was studied. The results show that the longitudinal wave velocity can be estimated more accurately by using the standing wave fundamental frequency. The influence of Poisson’s ratio needs to be considered when calculating the Young’s modulus of elasticity by using the longitudinal wave velocity.