Mechanical Performance of Auxetic Rotational Polygons Metamaterials Based on Simple Rectangular-Shaped Parts: Experimental Validation and FEA Modeling

This paper presents the design, fabrication, and mechanical characterization of rotational polygons auxetic metamaterial with a negative Poisson's ratio. The remarkable auxetic behavior demonstrated by the metamaterial was achieved through its cell structure, which consists of four rectangular-shaped parts that rotate around a fixed point. The metamaterial's mechanical performance was evaluated through experimental testing and finite element analysis (FEA) simulations. Simulations were performed using Abaqus computer-aided engineering (CAE), showing a good correlation with experimental results, with slight variations in force values during different stages of deformation. Stress distribution analysis showed that the maximum stress occurred at the junctions where the diamond-shaped units of the structure met, with a higher stress concentration observed in the lower half of the structure. Elastic strain distribution followed a similar pattern, with greater strain observed in the lower half, particularly in the central diamond-shaped gaps. Additionally, simulations of compression along the x-direction revealed a more pronounced auxetic effect than y-direction compression, where compression in the x-direction caused contraction in the y-direction. The force-displacement curve for x-direction compression showed a higher peak force compared to y-direction compression, with the force reaching a maximum of 3.26kN. The study also demonstrated that the stress and strain distribution during x-direction compression closely resembled that observed at the end of the deformation in y-direction compression. Furthermore, results reveal that the structure absorbs nearly four times more energy along the X direction than the Y direction, attributed to its enhanced auxetic behavior in the X direction. In terms of energy absorption, it was observed that a smaller gap size resulted in a higher capacity for energy absorption. The study underscores the enhanced energy absorption and auxetic response of the developed metamaterial, making it well-suited for use in energy dissipation and impact-resistant applications such as footwear.