Customized behavioral characteristics of localized hierarchical 2D chiral metastructures

Nature provides a reference paradigm for customized mechanical properties and deformation characteristics of chiral structures, such as the hierarchical design strategy. Generally, the hierarchical chiral structures (HCS) have better compression performance and fracture resistance than the traditional first-order chiral structures (FCS). Despite so, only one kind of single deformation feature exists in the HCS configuration, which limits the engineering need for customized deformation behavior. In this paper, a localized hierarchical chiral design strategy is proposed, enabling the programmable morphing modes, suitable stiffness, strength, energy absorption and good fracture toughness simultaneously. The mechanical behavior of the localized hierarchical anti-tetrachiral, tetrachiral, anti-trichiral and trichiral structures are investigated by numerical simulation and experimental test for validating the rationality of the proposed design strategy. Results indicate that the localized hierarchical chiral design strategy can not only achieve multiple deformation modes but also have better fracture toughness, which can greatly expand the versatility of chiral structures.