Novel mechanical behaviors of DNA-inspired helical structures with chirality

Artificially designed structures with chirality are able to possess novel mechanical properties, for example, chiral honeycombs with negative Poisson's ratio and chiral acoustic metamaterials. Inspired by the chiral nature of double-helical structure of DNA molecule, in this paper, we present a design of helical structure with chirality and study its mechanical behaviors through experimental characterization, theoretical analysis and numerical simulation. A compression-twisting coupling deformation mode is observed for different types of DNA-inspired helical structures due to the competition among compression, bending and twisting energy of the helical structures and tension energy of the interlinks. We find that interlinks between two intertwined helices are decisive to the compression-twisting coupling deformation mode and both chiral and non-chiral behaviors of the structures can be quantitively captured by our established theoretical and numerical models. The influences of various geometric parameters on the stiffness and deformation mode are discussed. Finally, we present two types of superposed structures that behave differently, showing a high designability of the DNA-inspired structures. This study exploits the chirality of bio-inspired structures and uses it in structural design with novel mechanical properties, which may shed light on the development of bio-inspired mechanical metamaterials, impact energy absorbers, multi-functional composite materials and among others.