The effect of bending parameters on mechanical properties of bent oak wood

Abstract

The aim of this study was to investigate the mechanical properties of oak (Quercus petraea Liebl.) wood bent at different radii for locations of the tension and compression sides of wood using micro-mechanical test specimens. Two oak trees having straight stems with approximately 40 cm diameter were selected and two 4 m long logs were cut. Two different steaming pressures, two setting methods, and three different bending radii were examined. Additionally, a set of three controls was unbent. Mechanical properties including the modulus of rupture, modulus of elasticity in bending, tension and compression strength parallel to grain were measured from the convex and concave sides of all samples. Bending strength, modulus of elasticity in bending, tension strength and compression strength properties on convex sides were greater than the corresponding properties on concave sides. All strength values significantly decreased with decreasing bending radius on both sides. On the convex side, strength and stiffness values of oak wood at 300 mm radius were greater when compared to control groups while the strength and stiffness values of oak wood were lower for 100 mm radius. The values for 200 mm radius, on the other hand, were not significantly different compared to the control group value. On the concave side, all of the bent groups had significantly lower strength and stiffness values than that of control group. The effect of bending radius and setting method on the strength and stiffness values of oak wood was statistically significant on both concave and convex sides. The effect of steam pressure was not significant.