One possible way to use waste materials in the wood industry (chip, dust, smaller pieces) is to transform them into pellets. Pellet making requires, however, additional energy which should be as low as possible. Present work examines the possible origins of binding forces and experimental evidences show that also the presence of water on particle surfaces plays a definite role. It also turned out that the water potential curve of timber materials can successfully be used to estimate the relation of compaction pressure to the water tension of the material.
This article investigates the material thickness of the individual layer composition influence on the stresses under tension loading. The SolidWorks application was used for tension stress simulations. This simulated course of tensions was carried out for soft and hard materials as a function of their thicknesses. Hard material was represented by beech wood and soft material by aspen wood. Subsequently, the tensile stress and deformation of various two- and three-layered compositions of these materials were analyzed. Based on our results, the soft material was the weakest link; therefore, the ultimate tensile strength of the entire layered material is directly dependent on it. Hard material can withstand greater tensile stress and deformation without breaking, as soft material does.
Effect of loading type (compression and tension) on mechanical properties, including elastic constants, yield strength and ultimate strength of beech (Fagus orientalis) wood were studied based on experimental and numerical methods. The mechanical behaviors of beech wood in compressive and tensile states were simulated by finite element method (FEM) using mechanical parameters measured in an experiment. The results showed that the effect of loading types on mechanical properties of beech was statistically significant. The elastic moduli measured in tension were all bigger than those in compression, but the Poisson’s ratios determined in compression were bigger than those in tension. In compressive state, the yield and ultimate strengths of beech in longitudinal grain orientation were all smaller than those measured in tensile state, while the yield and ultimate strengths of beech in radial and tangential directions were higher than those of longitudinal direction. The results of the FEM in compression and tension were all well consistent with those measured by experiments respectively, and the average errors were all within 13.69%. As a result, the finite element models proposed in this study can predict the mechanical behaviors of wood in tensile and compressive states.