Figure 4.
The normalized spring energy landscape with respect to origami folding. The bistable characteristics shown in the dashed dotted lines become prominent if kII/kI ratio is high (a) or the stress-free resting folding angle deviates further away from 0° (b). Here, the stress-free configuration is defined as the stable folding shape where no creases are subject to deformation (hence zero potential energy); the bistable configuration is defined as the stable folding shape with some crease deformations. (Online version in colour.)