RESEARCH ON THE ANISOTROPIC PROPERTIES OF WOOD AT HIGH-RATE LOADING

Wood is widely used as a shock absorbing material. For the design of various protective structures and modelling their behaviour under dynamic load conditions, models equipped with authentic parameters are required. Since wood is a highly anisotropic material, this effect should be taken into account in modelling. The behaviour of the three structural types of wood is studied: pine, birch and sequoia. The stress-strain curves of pine and birch were obtained when the specimens are loaded along and across the fibers. To achieve a greater degree of deformation, the mode of multicyclic loading of the sample was used. For sequoia, an analysis of the effect of the stress-strain state on the strength and deformation properties was carried out. In the condition of uniaxial deformation, the nonuniformity of the radial expansion of samples with a different cutting direction relative to the grain was evaluated. It was found that the lateral confinement strongly affects the stress-strain behavior of the sequoia, suppressing cracks along the fibers and thereby slowing down the fracture.