A novel nested compression-torsion metamaterial with independently customized mechanical properties

Compression-torsion metamaterials demonstrate unexpected torsional deformation under axial loading as well as axial deformation under torsional loading. It brings new opportunities for displacement transformation or stress wave regulation. A sufficient number of cells is required within the metamaterial to improve the stiffness and stability. However, a long-standing challenge is the severely weakened compression-torsion coupling effect with the increase of cell number in transverse, as well as a difficult balance of the strong compression-torsion coupling effect with the stiffness and stability. These have brought great limitations to the application of multi-cells compression-torsion metamaterials. In the present work, we propose a novel nested metamaterial with chiral multi-cells, which can well achieve the balance between compression-torsion coupling effects and transverse cell number by improving the coordination among adjacent cells. More importantly, based on the established mechanical model, the axial stiffness, the torsional stiffness and the compression-torsion coupling coefficient of the metamaterial can be customized separately and independently without being affected by each other. Thus, the metamaterial with both strong compression-torsion coupling effect, high stiffness and high stability is obtained for the first time. The present work opens a door for customizing compression-torsion metamaterials with excellent composite performances and is expected to be a new start for promoting their significant applications.