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Nature materials usually possess unique hierarchical structures, like spongy bone, tendon and bamboo, and often exhibit remarkable mechanical properties. In this paper, inspired by the structural hierarchy of biological materials, the novel configuration design of unit cell with inner hierarchy was developed. The new lattice configuration takes advantage of the space filling and volume utilization of original BCC structure. The hierarchical lattices with 5 × 5 × 5 unit cells were manufactured by digital light processing (DLP) printing technique, using a hard-tough resin material. Numerical simulation and quasi-static experiment were performed to investigate the mechanical performance and deformation mechanisms of the lattice structures. The novel lattice configuration exhibits superior mechanical properties and enhanced energy absorption capacity with respect to conventional BCC lattice, e.g. when loading along x-axis, the improvement can be 38.9% for specific stiffness, 36.5% for specific energy absorption (SEA) and 73.1% for the crash load efficiency (CLE). Besides, the enhancement of mechanical performance and energy absorption capacity is more strong when loading along the z-axis. The mechanical interaction effect between structural hierarchy, e.g. master and slave cells, is proved to be the main reason that contributes to the enhancement of mechanical properties of hierarchical lattices. The designed novel configuration of hierarchical lattice will enrich the current lattice systems and promote the development of multifunctional applications in the future.
Wang et al. (Mon,) studied this question.