Elastic and Inelastic Properties of Wood and Wood-Based Materials

Abstract

Knowledge of the elastic and inelastic properties of wood and wood-based materials is an important basis for the calculation of deformations of wood under external loads and also for the deformations and stresses caused by moisture changes (e.g., stresses in wood during drying, deformation of wood elements in different climates). Wood is an orthotropic material. Thus, the properties depend on the anatomical wood directions (longitudinal, radial, tangential). In addition, there is a clear influence of the wood moisture, the temperature, and also the load type. Elastic properties include elasticity, shear modulus, and Poisson’s ratios. Wood properties are also time dependent; wood and wood-based materials are viscoelastic. There are creep and relaxation phenomena, which are greatly influenced by the climate but also by the type of stress and, in the case of bonded elements, the type of adhesive. The moisture-induced mechano-sorptive effect, which has not yet been sufficiently researched, is very important.