Transition Waves in Mechanical Metamaterials with Neighbor-Programmable Energy Landscapes

TL;DR

This paper demonstrates how arrays of monostable elastic units with neighbor-programmable energy landscapes can control transition wave propagation, enabling discrete and directional wave control in mechanical metamaterials.

Contribution

It introduces a novel mechanism for transition wave control using neighbor-dependent energy landscapes in monostable units, expanding metamaterial design options.

Findings

Transition waves can be initiated and controlled via neighbor interactions.

Wave speed and existence depend on geometric and mass design.

Neighbor effects enable domino-like wave propagation.

Abstract

Transition waves in mechanical metamaterials manifest themselves as propagating interfaces between different stable states in lattices composed of arrays of coupled, intrinsically bistable elements. Here, we show experimentally and numerically that arrays of elastic unit cells that are individually monostable, yet whose energy landscapes can be programmed through interactions with neighboring units, provide a rich and largely unexplored platform for transition wave propagation. We implement this concept by designing a unit cell comprising a von Mises truss supported by two vertical elastic beams. In one-dimensional arrays of such units, we demonstrate that each cell's energy landscape can change from monostable to bistable depending on the state of its neighbors. This neighbor-programmable energy landscape enables the controlled initiation and propagation of transition waves, giving rise to highly discrete, directionally unbiased, domino-like wave propagation. Experiments and numerical simulations show that the existence and speed of the waves are governed by geometric design and mass distribution. Our results establish neighboring effects as a distinct mechanism for transition wave propagation, expanding the design space of mechanical metamaterials beyond architectures that rely on intrinsically multistable building blocks.