3D Printed Nonuniform Auxetic Structure: Programmable Local Stiffness to Improve Mechanical Property by Avoiding Buckling

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 (n), per-layer dimension reduction ratio (Ln/ln) and spatial programming of unit cells to achieve a simultaneous optimization of load carrying capacity and auxetic property. Effects of layers (n) and dimension reduction ratio (Ln/ln) 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.