The objective of this work was to evaluate the effect of growth ring number (specimens including 2, 4, and 6 rings from the bark) and growth ring width on elastic constants in the radial direction of Populus x canadensis, which has not been revealed before. The longitudinal (2.25 MHz) and transverse (1 MHz) ultrasonic waves were propagated to calculate the longitudinal (VRR) and shear (VRL, VLR, VTR, and VRT) wave velocities and used to determine the elasticity modulus (ER), and shear moduli (GRL and GRT). The average growth ring widths of specimens including 2, 4, and 6 rings were 17.0 mm, 17.8 mm, and 18.2 mm, respectively. According to the results, only VRL steadily increased with increased ring number, while other velocities fluctuated. The same fluctuations were observed for moduli except for GLR, which constantly increased with ring number. The influence of ring number on velocity was statistically significant only for VRL and VRT. However, all moduli were significantly affected by ring number. Linear regression statistics revealed that there were significant relations between the ring width and density, VRL, VLR, VRT, GRL, and GRT.

Temperature is one of the environmental factors that has influences on the material properties, and its behavior in service life. In this study, effects of temperature and exposure duration on the ultrasound wave velocity, dynamic Modulus of Elasticity, Modulus of Elasticity in bending, and Modulus of Rupture were figured out by the transmission of ultrasound longitudinal wave and three points bending tests. According to results, all determined properties were decreased at intensive treatment conditions. Maximum decreases were 4.7, 16.6, 20.7, 34.1, and 8.7 % at 210 °C 8 h treatments for VLL, Edyn, MOE, MOR, and density, respectively. However, at moderate temperatures up-to 150 °C, properties (except density) were increased (VLL: 12.7%, Edyn: 20.2%, MOE: 18.1%, MOR: 11.7% at 80°C for 8h) with the increase in exposure time within the groups but decreased between the groups. Pearson correlation coefficients between the variables were ranged from 0.71 to 0.93 for Edyn-MOE, 0.47 to 0.85 for Edyn-MOR, 0.02 to 0.75 for Edyn-VLL, 0.71 to 0.88 for MOE-MOR, 0.02 to 0.78 for MOE-VLL, and 0.01 to 0.81 for MOR-VLL. Furthermore, R2 values were ranged from 0.7 to 0.9.

Softwoods are the basic and traditional raw materials for medium-density fiberboard production. However, sustainable consumption of wood material in the production of wood-based products requires material variety. Therefore, the usability of hardwood species in the production and its effects on the board properties should be of interest. Considering this, the influence of oak utilization percentages (30 %, 50 %, 70 %, and 100 %) on the physical (density, thickness swelling-TS 2 and 24 h) and mechanical (modulus of rupture, modulus of elasticity, internal bonding, screw holding resistance, and Janka hardness) properties of medium density fiberboard was evaluated in this study. Boards were factory-made instead of laboratory-made using Quercus petraea (oak), Fagus orientalis (beech), and Pinus sylvester (Scots pine) fibers. According to the results, the modulus of rupture, modulus of elasticity, and Janka hardness values were increased when medium-density fiberboard was produced using only oak fiber. On the contrary, thickness swelling, screw-holding resistance, and internal bonding properties were decreased.

Aim of study: Drying in kilns becomes one of the most significant procedures for the optimal use of wood products since the dimensions alter with changes in relative humidity. Computational fluid dynamics analysis of an unloaded lumber-drying kiln and positioning of the timber to be dried were aimed. Material and methods: The heat and flow analysis of the lumber-drying kiln was analyzed using ANSYS software. Concrete and aluminum were chosen as the floor and wall materials, respectively. The wall thickness was taken as 1 meter. Gravity forces were also taken into account in the study, the number of elements of the created mesh is 87057 and the number of nodes is 17730. Main results: The flow characteristics and temperature analyses formed in the study shed light on the lumber-drying kilns planned to be built. Preliminary information is provided about the positioning of the lumbers to be dried according to flow paths and temperature distributions. Highlights: Flow analyzes of the unloaded lumber-drying kiln were undertaken and streamlines were shown. The thermal analysis of the hot air directed from the fans together with the concrete floor of the drying kiln and the walls made of aluminum panels was made.