Bistable shallow arches: a new building block for nonlinear mechanical metamaterials

Snap-through instability of shallow arches is a well-known phenomenon and it has been extensively investigated in the literature. However, the mechanics of shallow arches has not been exploited yet for engineering nonlinear mechanical metamaterials. In this study, we use shallow arches as building blocks for realizing snapping-through bistable nonlinear structures.
By carefully assembling shallow arches in 2D arrangements, we can engineer fully snapping unit cells, which snap between two equally stable energy configurations. These unit cells can tile a 2D space which will have both bistability and snapping-through behavior. In this 2D array, the snapping of a unit cell triggers the snapping of the neighbor cells allowing the propagation of a “snapping wave” in the whole structure. We also show that it is possible to design snapping unit cell showing different configurations accordingly with the specific type of mechanical applied stimulus (i.e. moments, concentrated forces etc.).
We successfully prove that a fully reversible nonlinear mechanical metamaterial by harnessing shallow arches snap-through instability is viable. This anticipates being a promising avenue because its versatility in both the 2D space tessellation and the shallow arch design (i.e. bilayer shallow arches).