Effect of crease curvature on structure and instabilities of the origami waterbomb base

A straightforward folding process transforms a planar, 2D sheet into the 3D origami structure known as the waterbomb base, which consists of alternating mountain and valley folds that meet at a central vertex. Futhermore, transverse force applied to the central node of the tent-like structure drives snap-through between two bistable configurations. Thus, the waterbomb base serves as an easy-to-manufacture switching actuator, and has earned popularity in origami engineering as a result. In this work, we explore how further tunability may be accessed by introducing nonzero crease curvature, which causes facets to bend and store elastic strain energy. Through experiments and simple modeling, we show how geometry and crease curvature affect the folded shape and the loading response of this origami structure. We focus in particular on local buckling events, which precede global snap-through in the curved-crease origami waterbomb base.