Origami Metamaterials with Near-Constant Poisson Functions over Finite Strains

Origami-based structures have gained interest in recent years due to their potential to develop lattice materials, called metamaterials, the mechanics of which are primarily driven by the unit cell geometry. The folding deformations of typical origami metamaterials result in stretch-dependent Poisson's ratios, and therefore in Poisson functions with significant variability across finite deformation. This limits their applicability, because the desired response is retained only for a narrow strain range. To overcome this limitation, a class of composite origami metamaterials with a nearly a constant Poisson function, specifically in the range -0.5 to 1.2 over a finite stretch of up to 3.0 with a minimum of 1.1, is presented. Drawing from the recently proposed Morph pattern, the composite system is built as a compatible combination of two sets of cells with contrasting Poisson effects. The number and dimensions of the cells were optimized for a stretch-independent Poisson function. The effects of various strain measures in defining the Poisson function were discussed. The results of the study were validated using a bar-and-hinge-based numerical framework capable of simulating the finite deformation behavior of the proposed designs. (C) 2021 American Society of Civil Engineers.