Detection and Assessment Healthy Situation of Poulus Euphratica Oliv. with Stress Wave
Shanqing Liang, Nana Hu, Lanying Lin, Feng Fu
The defects of tree trunk of Poulus euphratica Oliv were inspected by stress wave method and diagnosed with transmission time and velocity. The reference values of transmission time of unit length and velocity from stress wave were used to assess the healthy situation of tree trunk. The goal is provide fast inspecting technology and assessment method for the historic trees in China. The results shown: 1) Single-path method of stress wave is effective nondestructive method to diagnoses the defect of wood, but it can not effective assess wetwood in standing trees using the reference value of unit length transmission time (670 m/s )and average velocity (942 m/s), there would have more accurate assessment results if reference value be summarized from sound wood and used to diagnoses healthy situation of tree trunk; 2) Two directions testing of stress wave can not accurate diagnose the edge crack and small area decay in stem, multitude point test should be used to get more useful information of wood ; 3) the multitude point test from single-path stress wave shown that the trend of velocity of healthy tree trunk was increasing firstly with the angle increase and decreasing when the transmission angle more than 180o. There has a binomial formula relationship between velocity and transmission angle and the correlation coefficient arrived at 0.9942. This velocity trend of cross-section in healthy tree trunk and binomial formula can be used to diagnoses the defects of tree trunk.