Research Information System
Russian Journal of Nondestructive Testing, vol.58, no.7, pp.548-562, 2022 (SCI-Expanded, Scopus)
Abstract: The influence of temperature and exposure duration on the twelve elastic constants of Turkish red pine has not been reported yet. In this study, the effect of temperature (110, 160, and 210°C) and treatment duration (2, 5, and 8 h) on the Young’s and shear moduli and Poisson’s ratios were figured out by non-destructive testing. Ultrasound (1 MHz) transverse and 2.25 MHz longitudinal) propagation through the axis and 45° off-axis samples with around 20 × 20 × 20 mm dimension. Ultrasonic wave velocities (UWV) were calculated and used to determine diagonal and off-diagonal terms of the stiffness matrix. The compliance matrix which was used to calculate the elastic constants was obtained by the inverse of the stiffness matrix. According to the results, consistent increases or decreases in the elastic constants with the increase in duration and temperature were not generally observed. Only EL at 110 and 160°C, GTL at 110°C, and νRL and νLR at 210°C presented consistent decreases. However, in the literature, treatment at low temperatures provided some improvements which are opposed to the results of this study, particularly for moduli values. For example, at 210°C–2 h treatment, moduli values were increased except GTR. The same is true for 210°C–5 h except for EL and GTR. According to ANOVA results, differences between the means of all properties are statistically significant except νLT and νRT (P > 0.05). When compared to the reported values, there are significant differences between the VLL and EL, while there is harmony for density. The average VLL of the unmodified samples was around 28.8% lower than the reported speed, and it’s thought that this could be one of the reasons for the remarkable low average dynamic EL (5792 MPa) value of the unmodified samples than the reported static value of 9200 MPa even the literature says dynamic values are generally higher than those of statically determined.