Weakening-induced Snap Instability as a Novel Reusable Force Protection Mechanism

We present a novel reusable force protection mechanism equipped with snap instability that is induced by weakening boundary conditions. The geometry of the proposed structure comprises one column and two flanges attached to its ends, and it allows the structural end conditions can alter between fixed supports and pinned supports. Switching between the fixed and the pinned supports results in elastic snap instabilities and it enables the structure to possess asymmetric equilibrium paths, whose loading and unloading paths are different. These snap instabilities induce hysteresis in the load-displacement curve, and external energy is converted in form of dynamic motion. After removing the external force, the structure elastically recovers to its initial configuration so that it can repeat the same force protection process. We report a combination of desktop-scale experiments, finite element simulations, and the Elastica analysis to explore the underlying mechanism of the unique structural behavior of the proposed structure. Given that the proposed reusable force protection mechanism exploits elastic instability, our study opens the possibility for practical applications over a wide range of length scales.