Morning glory-inspired lattice structure with negative Poisson's ratio effect

Negative Poisson's ratio (NR) structures have compression-contraction properties. Many studies have focused on the NR effect of artificially designed microstructures, but very few studies have been conducted on biomimetic NR structures. In this study, inspired by the geometric features and living habits of a plant called morning glory, a biomimetic lattice structure is proposed. A finite element model of the morning glory-inspired lattice structure (MGS) was established and the sample was prepared by 3D printing. Axial compression experiments and simulations were performed, and the MGS exhibited the characteristics of light weight, efficient energy absorption, and the NR effect. The mechanisms of the NR and compression force characteristics were analyzed in detail. In addition, many MGS models have been proposed, based on various connection modes of cells. The effects of the cell distance and cell connection modes on the compression behavior of the MGS were further studied. It was found that the energy absorption efficiency and NR effect of the MGS deteriorated with an increase in vertical cell spacing, and the energy absorption efficiency and NR effect of the MGSs tended to contradict each other. Furthermore, the minimum NR (MNR) values obtained for W5MG and F6MG were –1.509 and –1.480, respectively. In summary, the MGSs have broad application prospects.