WOOD RESEARCH Volume 68, Number 4, 2023
Abdurrahman Karaman and Mehmet Nuri Yildirim

EFFECT OF MATERIAL, ADHESIVE AND LOADING ON THE STIFFNESS OF WOODEN DOWEL JOINTS

The objective of this study was to evaluate the effects of selected parameters, such as type of loading (compression and tension), the wooden dowel species, and the adhesives type on the joint stiffness. Beech, oak, and Scots pine woods were used as wooden dowel material, and polyvinylacetate (PVAc) and polyurethane (PUR) adhesives were used as adhesive agents. Elastic stiffness on diagonal tension and compression tests were applied on 120 pieces of test samples prepared. The results showed that there was found out that the highest average elastic stiffness value of 656 Nm/rad was achieved in the oak dowel joints bonded with PVAc adhesive under compression loading. The lowest average value of 293 Nm/rad was found in the Scots pine dowel joints subjected to compression stress using PUR adhesive. On average, the elastic stiffness of the oak dowel joints bonded with PVAc adhesive was 17% higher than the elastic stiffness of the Scots pine dowel joints bonded with PUR adhesive. The influence of the wooden dowel species and the adhesive type were found statistically significant

WOOD RESEARCH Volume 65, Number 3, 2020
Nurdan Cetin Yerlikaya and Abdurrahman Karaman

Effect of the fabric reinforcement of structural holes in wood based panels

The objective of this study was to determine the effects of the glass fiber fabric reinforced holes in MDF, PB, OSB, and PL. The fabrics of 19 mm or 50 mm wide were used to reinforce the edge or flat surface of test specimens. The experimental sample groups were formed in 34 different ways. Three different holes configurations were prepared. The samples were subjected to the 3 points bend testing in the flatwise and edgewise directions. As a result of tests, bending strength and modulus of elasticity were determined. The data obtained separately in flatwise and edgewise bending tests were subjected to multiple variance analysis. According to experiment results, the lowest values were obtained in the “fabricless” in both tests. The lowest value was obtained as 12.35 N.m-2 (in PB material) in the group 12, which has samples with the fabric on the edge and 2 holes on the surface in the flatwise test, while the highest value was obtained as 49988 N.m-2 (in PL material) in the group 19, which has samples with the fabric on the bottom edge and holeless in the edgewise test. According to the materials, the lowest values were as 18.32 N.m-2 in PB material, while the highest values were 49988 N.m-2 in PL material. It was determined that the BS and MOE values decreased between 0.3 and 49% in terms of the effect of the hole with fabric on the edge. In the holeless groups, the lowest values 18.32 N.m-2 in flatwised were obtained in fabricless group in PB, while the highest values 49988 N.m-2 in edgewised were obtained in the group of fabric on top surface in PL. The results showed that the fabric reinforcement has a positive impact on the strength.

WOOD RESEARCH Volume 66, Number 2, 2021
Abdurrahman Karaman, Mehmet Nuri Yildirim, and Onder Tor

Bending characteristics of laminated wood composites constructed with black pine wood and aramid fiber reinforced fabric

The aim of this study was to determine the 4-point bending strength and modulus of elasticity in bending of Black pine wood laminated materials reinforced with aramid fiber was bonded using epoxy or polyurethane glues separately. The samples were prepared in accordance with the TS 5497 EN 408 (2006). The results of the study determined that the highest value for static bending strength was found in the laminated wood samples (83.94 N.mm-2) that were prepared using inter-layer aramid fiber reinforced polymer (AFRP) and epoxy glue. The highest value of modulus of elasticity in bending was found in the samples prepared with inter-layer epoxy and AFRP (10311.62 N.mm-2). It was observed that the samples parallel to the glue line of the laminated material showed higher performance compared to those perpendicular to the glue line. The data obtained as a result of this study demonstrated that aramid fiber reinforced Black pine wood laminated materials can be used in the building industry as building materials.