Abstract
Auxetic metamaterials have unique structural designs exhibiting zero or negative Poisson’ ratios during stretch/compression processes, which enable many critical applications such as sensing technology, wearable devices, and weight reduction parts. However, it is difficult to achieve ideal performance of various structural designs through geometry manipulation due to the beam/wall buckling under large strain. One way to minimize the occurrence of buckling is by introducing the high elasticity on the joints, but trade-offs exist among different mechanical behaviors. To this end, this study proposes to use a multi-material combining with the structure optimization to design an auxetic structure. The basic re-entrant structure is employed due to its simplicity, and finite element method (FEM) is adopted to demonstrate the effectiveness of this newly proposed strategy regarding the auxetic behaviors. For this multi-material structure, a different Young’s modulus is designed to apply on the additional arch structure. A series of simulations, which consider the influence of the mechanical properties, are conducted to investigate the change of auxetic behaviors such as stress distribution, Poisson’s ratio, and equivalent Young’s modulus against the applied material properties. The results indicate that the mechanical properties are strongly affected by the geometry design and the applied materials properties. Meanwhile, the buckling effect of the beam/wall could be eliminated if the hinge strength is small enough. The trade-off between equivalent mechanical properties and Poisson’s ratio could also be tuned through this newly material-based design.
