No abstract

The research determined the resistance to compression and low velocity impact of wood-based sandwich panels, the face sheet made of high-density fiber board, and high pressure laminate, while its auxetic lattice core was made by 3D printing using LayWood bio-composite filament. The core's auxetic property (i.e. exhibiting negative Poisson's ratio) was observed within the planes parallel to the facings. The ability of particular types of multilayer panels to absorb the energy was also determined. Based on the analysis of the obtained test results, it was proven that the core denoted as B, with inclination angle of the cell ribs $${{\varphi }_{x}=\varphi }_{y}=65^\circ$$ φ x = φ y = 65 ∘ , shows the highest compressive strength. It was determined that the dynamic load causes a very high overload in high-density fiber board face sheets. This results in damage to the sandwich panel surface and core structure. Cells of type B favorably minimize the differences in absorbed energy when using different face sheets and the energy value for low velocity impact. Taking into account the amount of absorbed energy, the most attractive is the panel with the D-type orthotropic core characterized by an inclination angle of the cell ribs $${\varphi }_{x}= 30^\circ , {\varphi }_{y}=60^\circ$$ φ x = 30 ∘ , φ y = 60 ∘ . The amount of energy absorbed by samples with high-density fiberboard face sheets increases significantly depending on the impactor's energy. For panels with face sheets manufactured from high-pressure laminate, the amount of energy absorbed decreases.

Sandwich panels most commonly used in the furniture industry are layered structures composed of a hexagonal cell paper core. The use of wood-based composites in modelling truss and pyramidal cores of layered furniture panels is rather scarce. The effect of geometry in the auxetic truss core on the mechanical properties of manufactured wood-based materials was primarily explored in this study. Moreover, the need to conduct further studies was also stressed to determine the elastic properties of cells and cores manufactured from wood filaments using 3D printing. The aim of this study was to determine the effect of the type of filament used in 3D printing and the geometry of pyramidal core cells on elastic constants in cores with identical relative density. This paper presented analytical models of manufactured cells, results of numerical calculations performed using the finite element method, as well as experimental tests determining elastic constants of the cores. Digital image analysis was used and showed that cell geometry had a considerable effect on elastic properties of the core while maintaining identical relative density of these structures. The angle of cell arms had a particularly marked effect on these properties.