Mechanical properties assessment of Cunninghamia lanceolata plantation wood with three acoustic-based nondestructive methods
2010
Yin, Y., Chinese Academy of Forestry, Beijing (China) | Nagao, H. | Liu, X. | Nakai, T.
The objectives of this study were to establish the method of evaluating wood mechanical properties by acoustic nondestructive testing at standing trees and at logs of a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation, and to compare three acoustic nondestructive methods for evaluating the static bending modulus of elasticity (MOE), modulus of rupture (MOR), and compressive strength parallel-to-grain (sigmasub(c)) of plantation wood as well. Fifteen Chinese fir plantation trees at 36 years of age were selected. Each tree was cut into four logs, for which three values of dynamic modulus of elasticity, i.e., Esub(sw), of the north and south face based on stress waves to assume the measuring state of the standing tree, Esub(fr), longitudinal vibration, and Esub(us), ultrasonic wave, were measured in the green condition. After log measurements, small specimens were cut and air-dried to 12% moisture content (MC). Static bending tests were then performed to determine the bending MOE and MOR, and compressive tests parallel-to-grain were made to determine sigmasub(c). The bending MOE of small clear specimens was about 7.1 % and 15.4% less than Esub(sw) and Esub(us), respectively, and 11.3% greater than Esub(fr). The differences between the bending MOE and dynamic MOE of logs as determined by the three acoustic methods were statistically significant (P 0.001). Good correlation (R
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