Multi-step self-guided pathways for shape-changing metamaterials

Abstract

Multi-step pathways-which consist of a sequence of reconfigurations of a structure-are central to the functionality of various natural and artificial systems. Such pathways execute autonomously in self-guided processes such as protein folding and self-assembly, but have previously required external control to execute in macroscale mechanical systems, provided by, for example, actuators in robotics or manual folding in origami. Here we demonstrate shape-changing, macroscale mechanical metamaterials that undergo self-guided, multi-step reconfiguration in response to global uniform compression. We avoid the need for external control by using metamaterials that are made purely of passive components. The design of the metamaterials combines nonlinear mechanical elements with a multimodal architecture that enables a sequence of topological reconfigurations caused by the formation of internal self-contacts between the elements of the metamaterial. We realize the metamaterials by using computer-controlled water-jet cutting of flexible materials, and show that the multi-step pathway and final configuration can be controlled by rational design of the nonlinear mechanical elements. We also demonstrate that the self-contacts suppress errors in the pathway. Finally, we create hierarchical architectures to extend the number of distinct reconfiguration steps. Our work establishes general principles for designing mechanical pathways, opening up new avenues for self-folding media, pluripotent materials and pliable devices in areas such as stretchable electronics and soft robotics.

Excess floppy modes and multibranched mechanisms in metamaterials with symmetries

“…Mechanisms are collections of rigid elements linked by flexible hinges, designed to allow for a collective, floppy motion of the elements. More recently, floppy modes and mechanisms have received renewed attention in the context of mechanical metamaterials, which are architected materials designed to exhibit anomalous mechanical properties, including negative response parameters, shape morphing, and self-folding [6,7,[12][13][14][15][16][17][18][19][20][21][22]]. An important design strategy for mechanical metamaterials borrows the geometric design of mechanisms, and replaces their hinges by flexible parts which connect stiffer elements [22].…”

“…Here we address two key issues. First, what is the multiplicity and statistics of EFMs in diluted lattices as considered recently [21,36,37] [Fig. 1(b)].…”

Metal–Organic Frameworks in Modern Physics: Highlights and Perspectives

“…This arrangement facilitates complicated mechanical behavior under external stimuli, and the literature is full of articles devoted to analysis of the unconventional mechanics of MOFs. [170] Metamaterials also demonstrate unconventional mechanical behavior. ), which is characterized by the different interactions (mechanical, electromagnetic) between the central element, a meta atom of a specific shape and size, with its neighbors.…”

Folding of Tubular Waterbomb

“…Mechanical metamaterials are artificially designed structures that offer extreme and unusual, yet useful, mechanical properties determined by their structural and geometric configurations rather than only intrinsic material properties of their composing elements. Conventional mechanical metamaterials are often formed by quasi-1D rods or links [1][2][3][4][5][6].…”