A novel lightweight tetrachiral metamaterial enabled by additive manufacturing for tunable mechanical response

Tetrachiral cylindrical metamaterials exhibit unique deformation characteristics arising from their rotational unit-cell topology and continuous ligament network. While their global mechanical behavior is strongly governed by geometric parameters, the specific influence of ligament thickness on compressive performance and auxetic response remained unexplored. This study addresses this gap through a systematic numerical and experimental investigation. A series of five tetrachiral cylindrical structures sharing identical outer dimensions, unit-cell geometry, and lattice orientation were designed, with ligament thickness varied between 0.2 and 1.0 mm. Quasi-static compression was simulated using a finite element to capture the full deformation process, including nonlinear stiffness evolution, progressive instability, and pseudo-densification. The simulations reveal that ligament thickness plays a dominant role in controlling global stiffness, deformation stability, and energy dissipation capacity. Increasing ligament thickness led to an approximately five-fold increase in load-bearing capacity and a 2.4-fold improvement in specific energy absorption. In addition, ligament thickness significantly altered local deformation mechanisms, shifting the response from relatively homogeneous chiral rotation to pronounced strain localization in thicker-ligament designs. All configurations exhibited strong auxetic behavior, with negative Poisson’s ratios ranging from −2.8 to −2.2. To assess the predictive capability of the numerical model, a representative tetrachiral cylinder was fabricated using VAT photopolymerization-based additive manufacturing and tested under quasi-static compression. The experimentally measured response closely matched the numerical predictions, validating the modeling approach. The combined numerical–experimental results demonstrate that ligament thickness provides an effective and practical design lever for tailoring stiffness, energy absorption, and auxetic response, supporting their deployment in protective, and impact-mitigation applications.