Design, FDM printing, FE and theoretical analysis of auxetic structures consisting of arc-shaped and Dumbell-shaped struts under quasi-static loading

This paper presents the design, 3D printing, and testing of this novel type of auxetic structure formed with arc-shaped unit-cells (UCs). The mechanical behavior of two different re-entrant Dumbell (RED) and Multiple-Arc structures are evaluated. The metamaterials are fabricated using 3D printing via Fused Deposition Modeling (FDM) techniques. Quasi-static compressive loading tests are performed on these metamaterials, and the results are verified using Finite Element (FE) simulation and theoretical analysis. The results of the study reveal that the RED configuration, which includes Dumbell-shaped struts that exhibit negative Poisson's ratio (NPR) themselves, outperforms the Multiple-Arc, the traditional re-entrant circular (REC), and conventional re-entrant auxetic structures in terms of specific stiffness (E_s) specific energy absorption (SEA) and NPR values. In addition, the effects of the geometry parameters, including strut thickness to height ratio, length to height ratio, and angle of Dumbell strut on the SEA and NPR values of the RED structure, are investigated. The findings indicated that the SEA values improved as the thickness-to-height ratio and Dumbell strut angle increased, and the length-to-height ratio decreased. Additionally, the NPR value showed enhancement with increased thickness-to-height ratio and Dumbell strut angle. However, the thickness-to-height ratio did not significantly influence the NPR value.