Study on Velocities of Stress Wave Propagating in Standing Trees of Broadleaf and Needles Species

摘要

Introduction Stress wave nondestructive evaluation (hIDE) has been widely used for lumbers, logs, and even some wood products and mounts of researches were conducted in recent years while the very NDE method applying to the standing trees is still immature to predict the grade of trees before felling. In order to improve the ability of mechanical grading based on the traditionally established visual grading in cold area, especially in the northeast forest area of China, longitudinal velocities of stress wave propagating in standing trees in frozen and non-frozen status were measured and the determination data were analyzed via SPSS.