In this study, we examined stress wave velocity patterns in the cross sections of black cherry trees, developed analytical models of stress wave velocity in sound healthy trees, and then tested the effectiveness of the models as a tool for tree decay diagnosis. Acoustic tomography data of the tree cross sections were collected from 12 black cherry trees at a production forest. Trees were subsequently cut, and the disk at each test location was obtained to assess the true physical condition. Stress wave velocity data of different paths across grain, from radial to tangential, were extracted from the acoustic tomography data sets. Our analysis indicated that the ratio of tangential velocity to radial velocity in sound healthy trees approximated a second-order parabolic curve with respect to the symmetric axis θ=. 0 (θ is the angle between wave propagation path and radial direction). The analytical model was found in excellent agreement with the real data from healthy trees. Further examination indicated that the analytical model can be used to diagnose internal conditions of trees when a stress wave testing method is used in tree inspection.
Bibliographical noteFunding Information:
This research was made possible by the collaboration between the USDA Forest Service, Forest Products Laboratory and Zhejiang Agriculture and Forestry University in China. This study was supported in part by the Natural Science Foundation of China (Grant No. 61272313 ) and Zhejiang Provincial Science and Technology Project (Grant Nos. 2012C21015 and 2013C24026 ). The financial support to Dr. Guanghui Li’s visiting study at the USDA Forest Productions Laboratory (FPL) was provided by the China Scholarship Council (CSC).
- Internal decay detection
- Stress wave
- Velocity pattern