Impact energy absorption performances of ordinary and hierarchical chiral structures.

Auxetic chiral structures consisting of circular ring nodes and tangentially connected ligaments are engineered systems that exhibit excellent flexibility, vibration attenuation, impact resistance performances. In this paper, the out-of-plane dynamic crash behaviors of anti-tetrachiral, hexachiral and hierarchical chiral structures are studied. The energy absorption efficiency, plateau stress, peak stress of chiral structures with different ligament length, node radius, ligament thickness and level of structural hierarchy under different external crashing conditions are compared, and identical mass per area of different unit cell configurations are assumed. It is found that anti-tetrachiral structure is able to generate higher plateau stress and better energy absorption efficiency than hexachiral structures. Making use of the mechanical benefits of structural hierarchy, novel hierarchical chiral structures are proposed for improving the crash energy absorption abilities of chiral structures, and relations between crash energy absorption performances and unit cell geometries are explored, such as: energy absorption efficiency, plateau stress of chiral structures. Based on systematical analysis, optimized chiral and hierarchical chiral cellular structure can be designed for impact energy absorption in protective sandwich structures. • Novel hierarchical chiral metastructures are designed for energy absorption. • Energy absorption performances of ordinary and hierarchcal chiral metastructures are investigated systematically. • Hierarchical design can improve the impact energy absorption abilities of chiral structures drastically. [ABSTRACT FROM AUTHOR]