The in-plane tensile and shear properties of novel chiral cellular structures

Cellular structures have been widely studied and employed in engineering because of their excellent mechanical properties. To enrich the geometric diversity of cellular structures, we proposed two novel chiral cellular structures composed of half-periodic and full-periodic cosinoidal beams respectively in this paper. The in-plane elastic properties were studied by a combination of the energy method and the finite element analysis, and verified by the experimental test. The influences of geometric parameters on the elastic constants were analyzed. Then, the elastic properties of the two structures as well as the V-shaped chiral structure were compared. Finally, error analysis was carried out on the theoretical models. Results show that: (1) the two structures own considerably low equivalent elastic moduli and extremely high strain capabilities, and possess certain in-plane elastic coupling effects; (2) the elastic properties of the two structures are highly tunable with the variations of geometric parameters; (3) the elastic moduli of the two structures are lower than that of the V-shaped structure, and the structure with half-periodic beams exhibits the lowest in-plane stiffness and the highest strain capabilities; (4) the theoretical models without considering the internal axial force are convincible in predicting the elastic properties when the corresponding chord ratio is larger than 0.2. Generally, the proposed structures have great potential as flexible structures for morphing application.