Nature-inspired heterogeneous metamaterials: functional design framework

Heterogeneous mechanical metamaterials can achieve extraordinary properties through their complex and diverse microstructural designs. However, research on the functional realization by heterogeneous mechanical metamaterials in varying scenarios remains insufficient. Nature's materials generally feature irregular and multi-material characteristics, endowing them with remarkable functions such as mechanical stress regulation and crush protection. Accordingly, herein, we combine these two features to create a unified framework for the design of heterogeneous mechanical metamaterials. By optimizing the spatial distribution of a limited set of unit cells, we show that irregular and multi-material metamaterials can be assembled to achieve functions such as cloak, protection, and field control characteristics, demonstrating the universality of this framework. Although our optimized structures are irregular and non-periodic, the assembled materials exhibit spatially varying characteristics, allowing precise displacement or stress distribution adjustment in different control regions under various loading conditions to achieve functionality. Our approach excels in rapidly responding to new design scenarios that offer inspiration for the efficient design of functional metamaterials.