Relationships between mechanical properties of oak timber (Quercus robur L.)

Abstract

Abstract Ring-porous hardwoods such as oak are in high demand for furniture-making, cooperage, flooring, and construction. However, evaluating the quality of such timber is difficult and time consuming, and simpler tests are required. Models for predicting as many mechanical properties as possible, based on easier-to-determine mechanical tests, may help. In this study, the hardness, modulus of elasticity, bending, compression, and impact bending strength parallel to grain were tested on defect-free laths obtained from a sample of 42 oak trees. The relationships between the variables were investigated. Three models that relate the resistance to axial compression with bending strength and stiffness (R2>0.55; P<0.01) are proposed for defect-free oak timber. Selection of models mainly depended on the bias, which was highly variable among the models tested. The prediction models proposed in the international standard EN 384:2004 for structural dimension timber are not suitable for small clear wood specimens, especially in very elastic woods. The relative independence of hardness and impact bending strength as regards the other mechanical properties is also demonstrated.