Effects of annual ring number and width on ultrasonic waves in some softwood species

Abstract

The effect of annual ring number and width on the longitudinal (P) and transverse (S) ultrasonic wave velocities in the radial direction of black pine, Scots pine, Turkish red pine, and cedar softwoods was evaluated in this study. Annual rings were evaluated using high-resolution images captured with a Lumix camera. The 2.25 MHz P and 1 MHz S wave frequencies were propagated through the radial direction of small clear samples. An increase in ring number caused different changes in the P and S wave velocities. Only Scots pine and cedar presented continuous decreases in P and S wave velocities with the increase in annual rings. On the contrary, VR of Red pine slightly decreased and surpassed the initial value when the ring numbers increased from 5 to 10 and 15, respectively. Furthermore, the greatest decrease (4%) in the velocities was observed for VRL of Red pine. According to one-way ANOVA results, significant relations were only observed for VR vs. ring number of Black pine and cedar. R2 values ranged from 0.0001 (Red pine VR) to 0.18 (Cedar VR) for ring number and 0.0002 (Cedar VR) to 0.44 (Scots pine VR) for ring width. Furthermore, ANOVA results for linear regression analysis showed that VR of Scots pine and VR, VRL, VRT of Red pine can be statistically significantly predicted by the ring widths.