Numerical and experimental characterization of 3D-Printed elliptical anti-chiral metamaterials with box-Behnken optimization

In recent years, progress in architected lattices and high-resolution vat photopolymerization has renewed attention to auxetic designs that combine conformability with load-bearing capacity. Here, the mechanics of Digital Light Processing (DLP)-printed elliptical anti-chiral metamaterials were examined with the aim of establishing practical design rules for stiffness, energy absorption, peak load, and auxetic response. A Box-Behnken design was implemented over three geometric factors (curvature, thickness, width), and an elastic-plastic finite-element model calibrated from compression tests was validated against tests on representative lattices. ANOVA confirmed statistically significant models for all responses. Qualitatively, thickness governed elastic stiffness, maximum force, and energy absorption; width provided additional gains while helping preserve auxeticity; and curvature had a secondary effect on strength but reduced the magnitude of the negative Poisson’s ratio. Representative outcomes included elastic stiffness ≈ 3.0 kN/mm, ≈ 5.3 kN, specific energy absorption ≈ 339 J/kg, and a most-auxetic case of ν ≈ -1.61. A multi-response desirability search identified a narrow high-performance region favoring large width with moderate thickness and curvature, offering a balanced increase in load capacity and energy absorption while retaining auxetic behavior. The validated DOE/RSM framework provides clear, data-efficient guidance for tuning elliptical anti-chiral lattices toward protective and biomedical applications.