Mechanical Behavior of NiTi-Based Circular Tube Chiral Structure Manufactured by Selective Laser Melting

In this work, a new NiTi-based circular tube chiral (CTC) structure with compression-induced-twisting effect was proposed, inspired by the spiranthes cernua’s tendril, which was then manufactured by selective laser melting (SLM). The compressive deformation behavior and coupled twisting feature of NiTi-based CTC structure were disclosed in detail based on the experimental method and simulation approach. It was found that the twisting angle per axial strain λ achieved by the experiment and the simulation was roughly consistent with the result (1.5068°/%) based on the theoretical calculation within a small deformation. As the strain increased, the λ rapidly declined and finally stabilized at round 0.6°/%. Furthermore, the recoverable behaviors of the axial strain and the twisting angle after the unloading were also evaluated in views of the reversible martensitic transformation of NiTi alloys. After six cycles, the recoverable strain or twisting angle ratio could reach approach to 1. This work could be expected to provide a guiding significance to some degree for the development of functional components (such as smart actuators) with a stable and reversible twisting behavior applied in the aerospace field.