MATLAB codes: The MATLAB codes for the numerical cases mentioned in main manuscript are attached as electronic supplementary materials. from Kirigami-inspired rigid-foldable meta-structure with a bidirectional self-locking property

Self-locking is an attractive feature in origami structures that enables the foldable structure to withstand loads along the direction of deployment, without requiring extra locking elements. However, this feature is rarely observed in rigid origami because such structures can be easily folded or deployed along the deployment direction. Here, we introduce a novel origami meta-structure with both rigid foldability and bidirectional self-locking capacity based on a kirigami-inspired foldable icosahedron. The kinematic analysis demonstrates that a foldable icosahedron has two motion steps separated by a bifurcation point. By stacking two icosahedra together, we construct a rigid-foldable module capable of bearing both tensile and compressive loads along the direction of deployment. Through energy analysis and prototype experiments, we demonstrate that the bidirectional self-locking phenomenon originates from both the multiple motion steps of a foldable icosahedron and the torsional stiffness of creases. We arrange the module into a planar array and show its potential application in mechanical memory storage devices. This work paves a new way to design rigid-foldable and bidirectional self-locking origami structures.

自锁是折纸结构的一项极具吸引力的特性，可使可折叠结构承受展开方向的载荷，无需额外增设锁紧元件。然而，刚性折纸（rigid origami）中极少出现该特性，因为这类结构沿展开方向极易被折叠或展开。本文基于剪纸启发的可折叠二十面体（kirigami-inspired foldable icosahedron），提出一种兼具刚性折叠性与双向自锁能力的新型折纸超结构（origami meta-structure）。运动学分析表明，可折叠二十面体存在两个由分岔点（bifurcation point）分隔的运动阶段。通过将两个二十面体堆叠组合，我们构建出一种可沿展开方向承受拉压载荷的刚性折叠模块。通过能量分析与原型实验，我们证实双向自锁现象源于可折叠二十面体的多运动阶段以及折痕的扭转刚度。我们将该模块排布为平面阵列，并展示了其在机械存储设备（mechanical memory storage devices）中的应用潜力。本研究为设计兼具刚性折叠性与双向自锁能力的折纸结构开辟了全新路径。