Mechanical Behaviours Of Wood-Based Lattice Truss Core Sandwich Structures

The aim of the present study is to initiate an investigation based on the design of a large interconnected void space structure by using wood composites though snap-fit method to build the lattice truss core sandwich structures. The basic mechanical behaviours of the sandwich structures are investigated though experiments and mechanical models.In chapter one, the overseas and domestic research status of composite lattice truss core sandwich structures, wood engineering materials and wood sandwich structures are presented. The concept of wood-based lattice core sandwich structures is presented according to the former studies.In chapter two, the original materials, the manufacture processing of poplar laminate volume lumber, the configurations of lattice truss core sandwich structures and the snap-fit method are introduced. The snap-fit method is presented though the pictures of manufacture processing.In chapter three, the theory of bending vibration method and longitudinal sympathetic vibration method of non-destructive test method are presented. The comparisons of different failure modes, effective strength and effective modulus of wood-based lattice truss core sandwich structures under different load conditions are reported.In chapter four, the detective method of non-destructive test, original materials and lattice truss core sandwich structures’ mechanical properties are reported.In chapter five, the mechanical properties of the original materials are presented. The compressive properties of dowels are detected by column compression test, and the influence of the variability of wood is decreased though normality test. The non-destructive test method is used to evaluate the modulus of facesheets and the influence of drilling holes, and optimal select the facesheets of bending test specimen. The experimental results show that this methods are feasible. For the first time, the wood composites are used to manufacture wood-based lattice truss core sandwich structures though snap-fit method. The main failure mode of the sandwich structures is the shear failure of dowels under out-of-plane compressive load. Owing to the manufacture processing, the failure mode of the sandwich structures is the failure of the adhesive under shear load. The debonding of the dowels is the initial failure mode, and the facesheets are broken near the middle span of the bending specimens which is the ultimate failure mode under bending load. The failure mode of the sandwich structures is the break or delamination of the facesheet under in-plane compressive load. Using GFRP (glass fiber reinforced plastic) to reinforce the bending specimens of the sandwich structures, the effect of reinforcement is significant. Theoretical predictions and experimental results of the mechanical properties of the sandwich structures are in good agreement. However, the mechanical model should be improved in the future works.Compare with the traditional wood engineering materials and wood sandwich structures, the sandwich structures is lighting, superior specific strength/stiffness and designability. The wood-based straight lattice truss core sandwich structures can be applied to the area which need bear compressive load. The wood-based two-dimensional lattice truss core sandwich structures can be applied to the area which need bear compressive and shear load. Due to the interconnected lager space, the sandwich structures can achieve the purpose of multi-functionalization.