S2E7

Meta-structures and the quest for defect immune wave propagation

A design framework for deployable origami structures

Abstract:

Meta-structures are artificially engineered structures designed to exhibit properties not found in conventional materials. By careful design, one can obtain unprecedented control over various physical properties. Examples in mechanics includes structures having unique static and dynamic properties like negative Poisson’s ratio, zero shear modulus and non-reciprocal wave propagation.

Waveguides transporting energy and information are widely used in bulk and surface acoustic wave devices. They suffer from losses due to localization and scattering at defects and imperfections. In this talk, I will illustrate how such losses can be overcome by a new class of meta-structures: topologically protected waveguides. Inspired by recent developments in quantum condensed matter physics, such waveguides allow for one-way wave propagation along a boundary, immune to the presence of defects in the structure. Such waveguides have potential applications in acoustic signal processing, imaging and vibration isolation.

Abstract:

Shape-morphing finds widespread utility, from the deployment of small stents and large solar sails to actuation and propulsion in soft robotics. Origami structures provide a template for shape-morphing, but rules for designing and folding the structures are challenging to integrate into a broad and versatile design tool. Here, we address this challenge in the context of rigidly and flat-foldable quadrilateral mesh origami (RFFQM). First, we develop an efficient algorithm that explicitly characterizes the designs and deformations of all possible RFFQM. Then, we employ this algorithm in an inverse design framework to approximate a general surface by this family of origami. The structures produced by our framework are "deployable": they can be easily manufactured on a flat reference sheet, deployed to their target state by a controlled folding motion, then to a compact folded state in applications involving storage and portability. We demonstrate the accuracy, versatility and efficiency of our framework through a rich series of examples.