Abstract:

To investigate the effects of temperature and moisture content on the propagation velocity of stress wave in wood, we conducted stress wave tests on sixty korean pine(Pinus koraiensis) clear wood specimens at different moisture contents(MC)and temperatures (-30,-20,-10,-5,0,5 and 20 ℃ respectively)in laboratory. Based on this, the relationship between the propagation velocity of stress wave and moisture content or temperature was analyzed respectively, and the regression models among three parameters were built finally. The analysis results indicted that both moisture content and temperature were two important factors for affecting the propagation velocity of stress wave. Stress wave velocity decreased gradually as MC or temperature increased. Stress wave velocity is more significantly affected by moisture content as MC is below the fiber saturation point(FSP)than as MC is above the FSP. When MC was below 50%, stress wave velocity decreased linearly as temperature increased, but stress wave velocity had an abrupt jump near 0 ℃ temperature when MC was above 50%. The binary linear regression models between MC and the propagation velocity of stress wave for specific temperature conditions were found fitting to the experiment data very well(R²> 0.95).

Key words: stress waves, propagation velocity, temperature, moisture content, timber, pinus koraiensis