Stress–strain behaviour of wood in compression: Experimental and analytical investigations

• The stress–strain curves of beech and birch along the different orientations were investigated. • Simple and accurate mathematical models were developed to represent the stress–strain curves of the material. • The models are efficient in representing the complete stress–strain curves of wood by considering the micromechanical effects. • The proposed models accurately capture the behaviour of wood under various environmental or processing conditions. This study extensively investigates the compressive performance of two hardwood species (beech and birch) with the aim of developing simple yet efficient mathematical models to represent the stress–strain curves of wood along the different orientations. The proposed relationships were compared with the compressive data presented in this study and those compiled from the literature. Unlike models for cellular material used for wood in literature, the suggested relationships proved to be efficient in representing the complete stress–strain curves of wood by considering the micromechanical effects influencing the transverse behaviour of moderate- and high-density wood species such as beech and birch. The proposed models were shown to accurately capture the behaviour of beech and birch not only at standard testing conditions, but also at different environmental or processing conditions. Additionally, the models can successfully be applied to other hardwood and softwood species. These findings underscore the models' broad applicability and their value in advancing the understanding of wood's mechanical behaviour.