With the development of 3D printing technology, auxetic structures have attracted extensive attention due to their unusual mechanical properties. In this study, we design a 3D printed auxetic structure using 2D draft angles to achieve a tunable out-of-plane double hyperbolic buckling behavior by effectively continuously varying stiffness across thickness. The influences of radii and draft angles on the buckling behaviors of the 3D printed draft-angle auxetic structures are studied by finite element method (FEM). The constitutive relationships between stress, strain, radius, and draft angle have been formulated and discussed to identify the working principle behind the mechanical performance of draft-angle auxetic structures. Finally, the buckling behavior is modelled by a laminate structure, and the accuracy of these analytical results has then been verified by experiment. This study is expected to provide a design guideline for achieving tunable buckling behavior of auxetic structures via the novel stress mismatch of draft angles and thus continuously varying stiffness along the thickness direction. The current work constitutes an initial attempt to realize the tunability of the 3D out of plane deformation of 2D plane structures under in-plane compression.
With the development of 3D printing technology, programmable auxetic structures have attracted extensive attention due to their designable and abnormally mechanical properties. In this study, we design a 3D printed programmable auxetic star-like structures using number of layers [Formula: see text], per-layer dimension reduction ratio [Formula: see text] and spatial programming of unit cells to achieve a simultaneous optimization of load carrying capacity and auxetic property. Effects of layers [Formula: see text] and dimension reduction ratio [Formula: see text] on the mechanical and Poisson’s ratio behaviors of the 3D printed auxetic star-like structures are investigated by finite element method and verified by experiments. Finally, the unit cell spatial programming is designed and analyzed to avoid buckling and rotation, while increasing the load carrying capacity and auxetic property in a coordinated way. This study is expected to provide a design guideline for meta-star-like structure with both high load carrying capacity and auxetic property via a novel nonuniform stiffness structure design.
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