Damage-tolerant material design motif derived from asymmetrical rotation

Nature-inspired design motifs have contributed to the development of advanced materials. Here the authors present a segmental design motif to realize a compression-resisting lightweight mechanical metamaterial with a progressive failure behavior and rotational degree of freedom. Motifs extracted from nature can lead to significant advances in materials design and have been used to tackle the apparent exclusivity between strength and damage tolerance of brittle materials. Here we present a segmental design motif found in arthropod exoskeleton, in which asymmetrical rotational degree of freedom is used in damage control in contrast to the conventional interfacial shear failure mechanism of existing design motifs. We realise this design motif in a compression-resisting lightweight brittle material, demonstrating a unique progressive failure behaviour that preserves material integrity with 60-80% of load-bearing capacity at >50% of compressive strain. This rotational degree of freedom further enables a periodic energy absorbance pattern during failure yielding 200% higher strength than the corresponding cellular structure and up to 97.9% reduction of post-damage residual stress compared with ductile materials. Fifty material combinations covering 27 types of materials analysed display potential progressive failure behaviour by this design motif, thereby establishing a broad spectrum of potential applications of the design motif for advanced materials design, energy storage/conversion and architectural structures.

Automated summary

Nature-inspired design motifs have been crucial in advancing materials with both strength and damage tolerance. In this study, the authors present a segmental design motif extracted from arthropod exoskeleton to create a compression-resisting lightweight mechanical metamaterial. This design motif introduces an asymmetrical rotational degree of freedom, leading to a progressive failure behavior and increased energy absorbance capacity.