Axis 1 – Self-Adaptive Architectures:

Metamaterial with a twist

As for other types of so-called “metamaterials” (photonic, acoustical, sismic…), which are objects periodically structured at a sub-wavelength scale, there is a fair amount of hype developing mechanical metamaterials that can exhibit behaviours inaccessible to homogeneous materials and possibly interesting for structural control. A breakthrough discovery has been published in the Nov.24 issue of Science, and making its cover, thanks to a fruitful collaboration between researchers of EIPHI and KIT in Karlsruhe: from cubic building blocks, they purposely designed, modelled and fabricated an adequate chiral metamaterial that turns out to be efficient in converting, for the first time, a purely linear compression force into a purely rotating torsion. Such unusual deformation behaviour is indeed not allowed by the classical rules of solid mechanics. Moreover, this three-dimensional metamaterial is also providing enhanced rigidity while being prone to structural lightening. As a foreseen application, advanced mechanical designs based on such a metamaterial might be efficient in protecting structures from unwanted mechanical shock waves.

Artist view of a 3D mechanical twisted metamaterial made from an innovative two-photon-absorption-based 3D printing method with micrometre precision. © Tobias Frenzel (KIT)

T. Frenzel, M. Kadic, M. Wegener, “Three-dimensional mechanical metamaterials with a twist”, Science 358, 6366, 1072-1074 (Nov. 24 2017). DOI: 10.1126/science.aao4640