All-composite integrated 3D-Kagome lattice cores sandwich structure with flexible mortise-tenon joints

Composite lattice cores sandwich structures have shown obvious advantages in specific mechanical property and potential multifunctional integration. 3D-Kagome lattice core is regarded as a classic core configuration with relative optimal theoretical performance. However, it is still unavailable due to preparation problem of the overlap joint-node of composite cores. In this paper, a self-locking mortise-tenon joint method is presented to sucessfully fabricate the integrated 3D-Kagome cores with the expected mechanical properties. The out-of-plane compressive behaviour and energy absorption characteristics are experimentally studied. For the composite structures with various relative densities, three kinds of compressive curves are observed, following by different failure modes. An obvious bearing reinforcement emerges for the lattice cores with high relative density. As the length-to-thickness ratio of the core-rods increases, the initial peak strength and modulus of structures both decrease with a slowing rate. Though the mortises weaken the load-bearing capacity of core-rods, the active constraint of mortise-tenon joint suppresses an obvious degradation. The dominated failure more depends on the core-height than rod-thickness. The composite 3D-Kagome cores show more excellent mechanical properties than other similar structures, especially for the elastic strain before the initial peak stress. The semi-rigid power-wasting mortise-tenon joint and load-bearing characteristics of Kagome core together provide a large deformation tolerance at a relatively high stress level. All suggest that the presented 3D-Kagome lattice cores could be considered as a potential energy absorbing material.