Topological design of 3D chiral metamaterials based on couple-stress homogenization

The design of metamaterials brings the possibility of realizing novel properties beyond traditional materials. The coupling effects between tension/compression and torsion can be viewed as the chirality of materials, which is hardly to observe in uniform materials. In this paper, we present a systematic topology optimization approach to design a 3D metamaterial with chirality. The proposed method is based on the couple-stress homogenization, where effective moduli of a 3D material are calculated by a series of numerical tests for the unit cell. Then the optimization model and sensitivity analysis are developed for maximizing the chirality of a 3D cellular material. Novel designs of chiral metamaterials are obtained by the developed topology optimization method. The chirality of the newly obtained metamaterials is demonstrated by the twist deformation under the uniaxial compression. The developed approach is also applicable to explore for other novel properties of metamaterials.