A Kirigami Approach to Forming a Synthetic Buckliball

Abstract

The shape transformation of some biological systems inspires scientists to create sophisticated structures at the nano- and macro- scales. However, to be useful in engineering, the mechanics of governing such a spontaneous, parallel and large deformation must be well understood. In this study, a kirigami approach is used to fold a bilayer planar sheet featuring a specific pattern into a buckliball under a certain thermal stimulus. Importantly, this prescribed spherical object can retract into a much smaller sphere due to constructive buckling caused by radially inward displacement. By minimizing the potential strain energy, we obtain a critical temperature, below which the patterned sheet exhibits identical principal curvatures everywhere in the self-folding procedure and above which buckling occurs. The applicability of the theoretical analysis to the self-folding of sheets with a diversity of patterns is verified by the finite element method.

An Omnidirectional Encircled Deployable Polyhedral Gripper for Contactless Delicate Midwater Creatures Sampling

“…Among all kinds of foldable polyhedrons whose edges are all equal in length, it can be seen from Figure 5E that the deformation of a regular octahedron is the simplest, and its square hole after expanding is the largest which is helpful for the target to swim in. In addition, although the deformation mode of the basic deformable polyhedrons shown in Figure 5E is identical to the previous research about "the Buckliball," [24][25][26][27] the ways to achieve its deformability are different. More specifically, the origami method introduced in this article (convex every regular face into several rigid kite-shaped faces) ensures more definite trajectories, better bistability, and better controllability.…”

Mechanical behaviour of a creased thin strip

“…The fundamental principle of origami is to transform a flat sheet square (2-D) of paper into a finished sculpture (3-D) through folding and sculpting techniques along pre-defined creases. Because of its unique properties, origami has been imitated and developed to design foldable mechanisms (Hanna et al, 2014), self-deployable structures (Delimont et al, 2015), robots (Jayaram and Full, 2016), self-folding structures (Na et al, 2015), metamaterials (Overbelde et al, 2017), energy absorbing structures (Yang et al, 2016 and to solve plant structure folding (Couturier et al, 2013), soft matter folding (Lin et al, 2016) and even protein folding problems (Gethin and Sambrook, 1992). From an engineering viewpoint, mechanical properties of the crease for design-ing origami structures are of significant importance, which should be fully understood and characterised.…”