WOOD RESEARCH Volume 70, Number 4, 2025
DOAN VAN DUONG and MASUMI HASEGAWA

NONDESTRUCTIVE PREDICTION OF BENDING STRENGTH OF PINUS MASSONIANA LAMB. LOGS AND SMALL CLEAR SPECIMENS USING STRESS-WAVE MEASUREMENTS

The main objective of this study was to investigate the relationships between stress-wave velocity measured in logs and small clear specimens and the bending strength of Pinus massoniana trees planted in northern Vietnam. Stress-wave velocity (SWVL) and green wood density (WDL) were measured on logs collected from different heightlevels of 23-year-olds P. massonianatrees. Stress-wave velocity (SWVS), wood density (WDS), and bending strength (MOR) were subsequently determined on small clear specimens prepared from the logs. Regression analyses revealed significant correlations between SWVL and MOR (r = 0.73, P < 0.001) and between SWVS and MOR (r = 0.80, P < 0.001). These results show that stress-wave velocity measurements, whether taken on logs or small specimens, are effective for segregating P. massoniana lumber resources based on MOR. A more accurate prediction of strength was obtained when stress-wave velocity and log or specimen wood density were used together to calculate the dynamic modulus of elasticity of logs (DMOEL) or specimens (DMOES), respectively. The correlation coefficients were 0.82 (P < 0.001) between DMOEL and MOR, and 0.93 (P < 0.001) between DMOES and MOR.

WOOD RESEARCH Volume 70, Number 1, 2025
DOAN VAN DUONG, VAN HUNG HOANG, MASUMI HASEGAWA, and EVGENII SHARAPOV

THE INFLUENCE OF TREE AGE AND RADIAL POSITION ON THE STRESS-WAVE VELOCITY AND TIMBER PROPERTIES OF PINUS MASSONIANA LAMB. PLANTED IN VIETNAM

The main objective of this study is to investigate the influence of tree age and radial position on the structural properties, asair-dry density (AD), modulus of rupture (MOR), modulus of elasticity (MOE) and the stress-wave velocity measured on small specimens (SWVS). Results of analysis showed a highly significant effect of age and radial position on the SWVS, AD, MOR, and MOE. Stress-wave velocity and wood property traits tend to increase with increasing tree age. The SWVS and selected wood properties near the pith were significantly lower than those near the bark. Mean MOR and MOE of the timber had significantly (P<0.001) relationships with SWVS (r = 0.75 and 0.91, respectively), although in the case of MOR a model based on AD alone is slightly better (r = 0.79). There were also significant relationships of acoustic velocity measured in standing trees (SWVT) with mechanical properties measured destructively in small specimens implying that stress-wave method has a good potential for measuring static bending properties of P. massonianaplanted in Vietnam