An investigation of in-plane tensile properties of re-entrant chiral auxetic structure

A new auxetic structure, re-entrant chiral auxetic (RCA) structure, is proposed for the first time in this paper. The RCA structure combines the topological features of hexagonal re-entrant and anti-tetrachiral honeycombs. Additive manufacturing technique, stereolithography (SLA), and traditional waterjet machining (WJM) were employed to fabricate six samples made from photopolymer (VisiJet SL Flex) and aluminum alloy (6061), respectively. Quasi-static uniaxial tensile tests were conducted in the X and Y directions, respectively. Numerical models were developed using ANSYS/LS-DYNA and verified by experimental data. Deformation modes, stress–strain curves, and Poisson’s ratios were considered to examine the effects of loading directions and material types. A comparative study was conducted experimentally and numerically between the well-known hexagonal re-entrant honeycomb, and this newly developed RCA structure. The proposed RCA structure presented here was found to display lower density compared with re-entrant honeycomb. Moreover, it shows higher tensile properties and auxetic effect compared with re-entrant honeycomb when loaded in the X direction. The validated FEA models were employed to investigate the effect of friction on the deformation pattern and mechanical properties of the RCA structure when it is loaded in both directions.