Crack localization and depth prediction in wood based on anisotropic velocity model of acoustic emission

For identifying crack location and depth on wood surfaces, this study proposes a crack localization method based on the anisotropic velocity model of acoustic emission (AE) signals. First, AE signal propagation velocities in different directions were calculated based on time difference of arrival (TDOA), thereby establishing an anisotropic wave velocity model as a function of propagation angle. Second, eight cracks with varying depths were sequentially introduced at the same surface position with 5 mm increments, and the corresponding propagation path for each crack is reconstructed using the velocity model. A crack localization algorithm is developed based on the geometric relationship between the AE source and three sensors, enabling determination of the crack position range and subsequent prediction of crack location and depth. The results showed that the proposed method effectively identifies crack positions. When crack depth exceeds 10 mm, AE signal propagation paths change significantly, with relative errors between calculated and measured TDOA ranging from 5.0% to 17.6%. Base on this, the crack depth and location were calculated. The relative errors between the calculated and actual values range from −4.0 % to 16.7 % for depth and from 4.8 % to 13.3 % for location.