An optimized lozenge-chiral auxetic metamaterial with tunable auxeticity and stiffness

While auxetic metamaterials exhibit impressive mechanical traits, they frequently grapple with inherent conflict between their stiffness and auxeticity. In this study, we introduced an optimized lozenge-chiral auxetic meta-material (oLCAM) with the dual objectives of balancing the auxeticity and stiffness and achieving tunable properties concurrently. The mechanical performance of the proposed oLCAM was first compared with that of conventional lozenge auxetic metamaterial (cLAM) through both experimental and numerical studies. Herein, the transition stiffness (Etrans) was initially proposed as the typical metric evaluating the overall structural stiffness. Subsequently, the study proceeded to investigate the impact of crucial design parameters, specifically the angle of inclination and the radius of the circular core. The design method of oLCAM with tunable auxeticity and stiffness was finally established based on a multi-objective optimization model, achieving the balance be-tween the auxeticity and stiffness of oLCAM. The results revealed the proposed oLCAM obtained a more stable deformation mode than cLAM. Two geometric parameters verified their significance on the above mechanical properties of oLCAM. The resulting optimal oLCAM structure has been proven to obtain both comparatively prominent auxeticity and stiffness. The established design method may have the potential to broaden the possibilities for metamaterial design and performance tuning.