Three-dimensional mechanical metamaterials with a twist

TLDR

In classical solid mechanics, deformation is constrained by limited degrees of freedom, so pushing on a material does not normally cause twisting. The authors designed a mechanical metamaterial that twists left or right when pushed, showing that macroscopic chirality can be engineered to produce unusual deformation behavior. Frenzel et al., Science, this issue p.

Abstract

Getting twisted with metamaterials In the classical picture of solid mechanics, deformation in response to stress is constrained owing to limitations on the degrees of freedom. For instance, when you push on a material, you do not expect it to twist in response. Frenzel et al. designed a mechanical metamaterial with a pronounced twist to the left or right when pushed (see the Perspective by Coulais). Designing this type of chirality for a macroscopic material is unexpected, but it points to a more general strategy for developing materials with unusual deformation behavior. Science , this issue p. 1072 ; see also p. 994