Toughness enhancement of honeycomb lattice structures through heterogeneous design

Inspired by the microstructures feature in the architected composites, which are consisted of a stiff phase and a soft phase, the concept of varying the struts thickness in the uniform honeycomb (UH) is proposed to enhance the toughness of UH structures through heterogeneous design. We specifically examine the effect of the choice of reinforcement phase, particularly its patterning and organization, on the toughness and deformation mechanisms of heterogeneous designed hexagonal (HDH) lattices. The HDH lattice is fabricated by using the 3D-laser cutting, and the HDH lattice composite is made by a hybrid manufacturing process on this basis. The experimental results show that the crack paths of the substrate lattice are consistent with the lattice composite. With longer crack paths, the total energy dissipation of the HDH lattice composite is significantly enhanced, and thus the toughness increases accordingly. In addition, theory and simulation studies for the substrate lattice are also carried out to explore the crack deflection mechanism. These results provide tougher lattice structures and shed new insights into the structure–property relationship which may further facilitate the design and usage of lattices in a wide range of structural engineering applications.