Dynamic bifurcation of Resch-patterned origami for self-adaptive impact mitigation
A long-standing challenge in impact mitigation is the development of versatile and omnifarious protective structures capable of encompassing a wide spectrum of scenarios, for example, ranging from low-speed pedestrian impacts to high-speed vehicle collisions. However, most existing impact mitigation strategies rely on fixed geometries or pre-tuned material properties targeting specific impact speeds, lacking the ability to adapt in real time. Here, we introduce a Resch-patterned origami structure that hosts two distinct deformation modes: a monostable folding mode and a bistable unfolding mode featuring snap-through. Impact experiments reveal a dynamic bifurcation, wherein the incoming impact velocity determines which of the two deformation pathways is activated. Unlike kinematic or static origami bifurcations governed by geometric compatibility or imposed displacement, this dynamic bifurcation enables the structure to engage distinct energy-dissipation mechanisms under various impact conditions. We further demonstrate the scalability and practical relevance of this mechanism by fabricating tessellations in a bumper-like configuration and evaluating their performance using a pendulum-based mannequin impact test. These results establish dynamic bifurcation in origami-based structures as a strategy for scalable and programmable impact-mitigation systems that autonomously select deformation modes in real time, with potential applications in adaptive robotics, protective armor, and aerospace structures.