Multimodal origami shape memory metamaterials undergoing compression–twist coupling

Abstract

As origami structures display designable and predictable folding or unfolding shape changes, the origami-inspired mechanical metamaterials have recently been extensively investigated for applications in metamaterial engineering. There were many previous studies on the conventional hexagonal Kresling origami structures, however, there are many issues such as structural optimizations and designable strategies for the mechanical metamaterials, which have not been solved. To solve these issues, in this study, we studied the influences of crease direction, the number of sides, and unit arrangement on the origami structures. Effects of these parameters on mechanical properties and deformation behaviors of metamaterials were analyzed using finite element methods and experimental verifications. By adjusting the number of sides, the switching between monostability and bistability of the metamaterials was realized. The compression-twist coupling effect of these metamaterials can be adjustable and tailorable by arranging the chosen units in series. Designed foldable metamaterials are flexible, especially in their unfolding and folding directions, resulting in the achievement of an unstable compression state, i.e., the externally applied loads may cause the structure to unfold along the same compression path. Furthermore, shape memory polymer (SMP) has been printed using 3D printing technology to achieve the smart origami metamaterials, which endow the metamaterials with shape memory effect, self-adaptability and temperature-responsive mechanical behavior.

Rotating coupling of chiral identical twins in multimodal Kresling metamaterials for achieving ultra-high energy absorption

“…In our previous study [41], we found that the Kresling units present compression-twist coupling during the axial compression, and the axial stress values with the opposite chirality show no differences, whereas the torsional angles are opposite. Based on this result, we studied the differences between homochiral and antichiral unit connections.…”

“…Figure 11(a) shows the stress-strain curves under an axial compression, where the octagonal modules (8-pppp, 8-ppnn, and 8-pnpn) exhibit high stress and smooth curves. Due to the same stress in the unit with different chirality cases [41], the differences on mechanical behaviors of the modules are only influenced by the soft hinges. The quadrilateral modules have shown the lowest peak stresses.…”

“…The φ value of 4-pppp is 11.97 • , and that of 8-pppp is 8.09 • . Compared with the individual unit [41], the φ value of module after soft hinge connection is greatly reduced. It is because the coupling between units and hinges hinders the rotation of each unit.…”