Mechanical memory in 1D

Mechanical memory has now emerged as an organizing principle across many length and timescales, via the interactions of many interacting elements which can encode and reveal information within their configurations. I will talk about a pair of quasi-one-dimensional sytems which are simple enough to record a few bits of information in specific locations through well-characterized interactions: a folded tube of origami, and narrow tube of water beads. In both cases, we capture similar information about the configuration: each folded element, or each unit cell of spheres within the channel, acts as a bistable element that can be open/folded or dilated/compressed, and can be characterized by a bulk stiffness. In both cases, we find a one-dimensional material that exhibits return-point memory, and through repeated cycles of compression, we can record the connectivity of discrete, well-labeled states (e.g. 000110 for chain of 4 open and 2 closed units). In the cases where the origami units are decoupled, the system reduces to the Preisach model, and we can drive the bellows into a particular state via a prescribed sequence of compressions and extensions. In the case of the low-friction spheres or coupled origami units, the available states can exhibit defects and irreversibility, are more complex, and have less well-separated states, but retain many of the same features. By considering the mechanics of the units, we analyze the hierarchical structure of the transition diagrams, which includes Garden of Eden states and subgraphs that may provide insight into more complex glassy systems.