Parametric and experiment studies of 3D auxetic lattices based on hollow shell cuboctahedron

As a kind of mechanical metamaterials with negative Poisson's ratio (NPR), auxetic lattices possess unusual mechanical responses such as higher sensitivity to strain and reversibility after large deformation. Therefore, they are regarded as a potential candidate to sensors, actuators, and optics. Here, we designed four types of auxetic lattices with long stress plateau based on the assembly of hollow shell cuboctahedron. To begin with, experiments along with finite element simulations were performed to probe their auxetic behaviors under uniaxial compression, which give an excellent qualitative and quantitative agreement. To establish design criteria on specific applications, we systematically investigated the mechanical properties of the four kinds of lattices with different volume fractions, including critical stresses, strain–stress curves, strain energy densities, strain-dependent Poisson's ratios, and the length of stress plateau. The results demonstrate that these lattices can suffer from buckling with NPR in an extended range of volume fractions, and high reversibility was observed in several compressive loadings, which provides insight into energy absorption such as the body protection equipments and smart packaging material