Ductility improvement of metallic bars by bioinspired chiral microstructures

Abstract

Improving the deformability of metallic materials is of paramount importance in engineering practice. Inspired by the tendrils–pole structures widely existing in the plant kingdom, we present a high-performance design of chiral composite structures in this study. Through wrapping fibers spirally on the surface of a metallic bar or embedding helical fibers into its body, the fracture strain of the bar can be increased greatly. Theoretical analysis and numerical simulations are combined to investigate the mechanical behavior of the designed composite. The effects of the number, geometry, and distribution of fibers on the elastoplastic responses of the composite bar are examined. Failure mechanisms of the bar are revealed. The results show that the helical fibers can suppress the occurrence of strain localization bands, leading to the improvement of structural ductility. The findings are verified by experimental measurement. The mechanical property of the proposed structures can be easily tuned by changing the microstructural parameters, and thus this strategy can be applied in various structures.