Multi-feature bionic gradient hierarchical lattice metamaterials with multi-synergistic crushing mechanisms

A persistent challenge of the checkerboard lattice metamaterials has been the trade-off between the controllability in crushing process and the enhancement of mechanical properties, where high stability and customizability tend to yield relatively low energy absorption capacity. To breakthrough this challenge, a design strategy based on a multi-feature bio-inspired gradient hierarchical lattice is presented, drawing from the microstructure characteristics of biological tissue. Experimental results and finite element analysis demonstrate the efficient and strong crushing performances and low oscillatory responses of the proposed gradient hierarchical lattice structures, featured by the designable multi-plateau crushing characteristics due to the multi-synergistic mechanisms of multi-biomimetic incentives. Specifically, its initial peak crushing stress is reduced by 162.69%, and the energy absorption efficiency is improved by 62.19% relative to the original square lattice with the same relative density. Moreover, the 1st plateau width of multi-feature bio-inspired gradient hierarchical lattice is determined by the size ratio of the unit cells, while the 1st and 2nd plateau stresses are mainly tailored by the wall-thickness and the relative density, respectively. The multi-bionic gradient hierarchical design paves an exemplary pathway to enhance the crushing performance and mechanical controllability of the checkerboard lattices.