An emerging class of hyperbolic lattice exhibiting tunable elastic properties and impact absorption through chiral twisting

Lightweight lattice structures and chiral metamaterials have both received extensive attention during the past decades. This work builds up a systematic design procedure for an emerging class of architected materials, achieving chirality and achirality under the same framework of parameterization. The design of the so-called ‘hyperbolic unit cell’ takes inspiration ultimately from the double-layered morphology of the fore-wing shells of flying beetles, being intended to replicate the hyperbolic geometric feature. The tessellation schemes that populate the microstructure to a component level are stirred up by the similarity with Euclidean tiling of convex regular polygons. Numerical and experimental studies revealed a wide variation of elastic constants for hyperbolic materials maintaining the same volume fraction, making more visible their applications under various loading scenarios, including compression, tension and shear. Also, a significant twisting effect, observed on the chiral cellular material, is shown to be advantageous in the design of buffering plates and energy-absorbing devices.