Conclusions
We have analyzed and demonstrated highly versatile folding behavior of the Tachi-Miura Polyhedron (TMP) by employing rigid origami model and paper-based prototypes with self-folding creases. We showed that this volumetric origami can exhibit two drastically different configurations, collapsible and load-bearing ones, without modifying the predefined crease patterns. This is achieved by leveraging a mechanical bifurcation intrinsic in TMP, which enables in-situ transition between the collapsible and load-bearing states in an efficient and controllable manner. For experimental demonstrations, we employed a self-folding technique based on heat-shrinking films. Although this mechanism supports the one-way actuation only, we envision that the TMP cellular structures can also transform their shapes repeatedly by using two-way reversible actuation methods such as shape memory alloys and electroactive polymer actuators. This is possible because the kinematic nature of TMP allows the switching without hitting a singular state. While the contrast of load-carrying capabilities between compliant and sturdy modes was in the range of \(10^2\) for the paper model, we expect the contrast would vary depending on the types of materials, such as acrylic and 3D printed TMP architectures demonstrated in this study. We envision that the TMP architectures can be employed to a wide range of engineering applications, such as a portable bridge for disaster relief, deployable space habitat, and medical devices.