Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session A44: Focus Session: Extreme Mechanics: Origami, Kirigami and Mechanisms I |
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Sponsoring Units: GSNP GSOFT DPOLY Chair: Christian Santangelo, University of Massachusetts Amherst Room: 214D |
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A44.00001: How to keep your pants on: historic metamaterials and elasticity before the invention of elastic Elisabetta A. Matsumoto, L. Mahadevan How do you create stretching from an inextensible material? Remarkably, the centuries-old embroidery technique known as smocking accomplishes just this. With the recent explosion of origami-based engineering, the search is on for a set of design principles to generate materials with prescribed mechanical properties. This quickly becomes a complex mathematical question due to the strict constraints of rigid origami imposed by the inextensibility of paper. Softening these constraints by considering woven fabrics, which have two orthogonal inextensible directions and a skewed soft shear mode, opens up a zoo of possible configurations. We explore the emergence of elastic properties in smocked fabrics as functions of both fabric elasticity and smocking pattern. [Preview Abstract] |
Monday, March 2, 2015 8:12AM - 8:24AM |
A44.00002: Miura Tubes and Assemblages: Theory and Applications Evgueni Filipov, Glaucio Paulino, Tomohiro Tachi Origami systems inspired from the Miura-ori pattern are rigid and flat foldable meaning that they can fold completely by deforming only about prescribed fold lines. We investigate origami tubes and assemblages constructed from Miura-ori inspired sheets and use eigenvalue analyses to study their stiffness characteristics. A simplified bar model is used to model the stretching and shear of the flat panel segments and rotational hinges are used to simulate the bending stiffness of the panels and prescribed fold lines. We discuss the small to large deformation bending of thin sheets and show an improved method to estimate stiffness when modeling origami structures. The tube assemblages show interesting behaviors that make them suitable for applications in science and engineering. [Preview Abstract] |
Monday, March 2, 2015 8:24AM - 8:36AM |
A44.00003: Mulitshape Origami Metasheets Scott Waitukaitis, Martin van Hecke We show how origami-based folding structures are a platform for multistable metamaterials. Our focus is the simplest building block, rigid 4-vertices, which we demonstrate can have up to six stable states. We extend our results to non-Euclidean vertices, which enables us fine-control over the number of minima. Our results lay the foundation for building designer, origami-based shape-shifting structures. [Preview Abstract] |
Monday, March 2, 2015 8:36AM - 9:12AM |
A44.00004: Multi-stability in folded shells: non-Euclidean origami Invited Speaker: Arthur Evans Both natural and man-made structures benefit from having multiple mechanically stable states, from the quick snapping motion of hummingbird beaks to micro-textured surfaces with tunable roughness. Rather than discuss special fabrication techniques for creating bi-stability through material anisotropy, in this talk I will present several examples of how folding a structure can modify the energy landscape and thus lead to multiple stable states. Using ideas from origami and differential geometry, I will discuss how deforming a non-Euclidean surface can be done either continuously or discontinuously, and explore the effects that global constraints have on the ultimate stability of the surface. [Preview Abstract] |
Monday, March 2, 2015 9:12AM - 9:24AM |
A44.00005: Prediction of the force required to unwrap a thin-film origami structure Lee Wilson, Sergio Pellegrino We consider thin film membranes wrapped around a polygonal hub according to the origami crease pattern developed by Guest and Pellegrino [1]. The problem of unwrapping such membranes is important for applications such as space solar sails. Their deployment can be controlled by displacing four edge points radially outwards. During deployment the film buckles multiple times, creating a complex deployment force profile. We have used finite element simulations to investigate how different models of the creases affect the predicted force profile and we have compared the results of our simulations with experimental results for Kapton thin film thicknesses of 50um, 25um, 12.5um and 7.5um. The deployment force profile is also highly dependent on the initial packaged configuration of the film, which in our model is obtained by simulating the folding process from a flat state.\newline [1] S.D Guest and S. Pellegrino, Proc. First Int. Seminar on Struct. Morphology, R. Motro and T. Wester, eds. (1992) pp 203-215 [Preview Abstract] |
Monday, March 2, 2015 9:24AM - 9:36AM |
A44.00006: Making the Cut: Lattice Kirigami Rules Toen Castle, Yigil Cho, XingTing Gong, Euiyeon Jung, Daniel Sussman, Shu Yang, Randall Kamien Complex 3D structures can be built by bending and folding a flat sheet, as is done in origami. This paradigm can be extended by cutting and gluing the sheet as well as folding. The principles manifest in manipulating a piece of paper can translate across many length scales, limited only by fabrication methods. We explore and develop a simple set of rules that apply to cutting, pasting, and folding honeycomb lattices. We consider origami-like structures that are extrinsically flat away from zero-dimensional sources of Gaussian curvature and one-dimensional sources of mean curvature, and our cutting and pasting rules maintain the intrinsic bond lengths on both the lattice and its dual lattice. We find that a small set of rules is allowed, providing a framework for exploring and building kirigami - folding, cutting, and pasting the edges of paper. [Preview Abstract] |
Monday, March 2, 2015 9:36AM - 9:48AM |
A44.00007: Kirigami for Two-Dimensional Electronic Membranes Zenan Qi, Dario Bahamon, David Campbell, Harold Park Two-dimensional materials have recently drawn tremendous attention because of their unique properties. In this work, we introduce the notion of two-dimensional kirigami, where concepts that have been used almost exclusively for macroscale structures are applied to dramatically enhance their stretchability. Specifically, we show using classical molecular dynamics simulations that the yield and fracture strains of graphene and MoS$_{2}$ can be enhanced by about a factor of three using kirigami as compared to standard monolayers. Finally, using graphene as an example, we demonstrate that the kirigami structure may open up interesting opportunities in coupling to the electronic behavior of 2D materials. [Preview Abstract] |
Monday, March 2, 2015 9:48AM - 10:00AM |
A44.00008: Designing 3D Structure by 5-7 Kirigami Xingting Gong, Yigil Cho, Toen Castle, Daniel Sussman, Randall Kamien The purpose of this talk is to explore how one can create 3D structures from 2D materials through the art of kirigami. Kirigami expands upon origami by allowing not only folds, but also cuts, into materials. If we take an incompressible material such as paper and remove a hole from it, the paper will buckle into the third dimension once that hole is sealed in order to relieve strain. Thus, orienting cuts and folds in certain places throughout a sheet of paper can influence its ``pop-up,'' 3D structure. To narrow down the inverse design problem, we confined ourselves to making only one kind of cut (which we call the ``5-7 cut'') on a honeycomb grid, and we show how this single cut can give rise to arbitrarily complex three dimensional structures. A simple set of rules exists: (a) one 5-7 cut divides the material into 2 sections which can choose to pop-up or down independently of each other, (b) rows of uniform cuts must pop up or down in unison, giving (nearly) arbitrary 2D structure, and (c) the 5-7 cuts can be arranged in various ways to create 6 basic pop-up ``modes,'' which can then be arranged to give (nearly) arbitrary 3D structure. These simple rules allow a framework for designing targeted 3D structure from an initial 2D sheet of material. [Preview Abstract] |
Monday, March 2, 2015 10:00AM - 10:12AM |
A44.00009: Optimization of Actuating Origami Networks Philip Buskohl, Kazuko Fuchi, Giorgio Bazzan, James Joo, Reich Gregory, Richard Vaia Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. By leveraging design concepts from action origami, a subset of origami art focused on kinematic mechanisms, reversible folding patterns for applications such as solar array packaging, tunable antennae, and deployable sensing platforms may be designed. However, the enormity of the design space and the need to identify the requisite actuation forces within the structure places a severe limitation on design strategies based on intuition and geometry alone. The present work proposes a topology optimization method, using truss and frame element analysis, to distribute foldline mechanical properties within a reference crease pattern. Known actuating patterns are placed within a reference grid and the optimizer adjusts the fold stiffness of the network to optimally connect them. Design objectives may include a target motion, stress level, or mechanical energy distribution. Results include the validation of known action origami structures and their optimal connectivity within a larger network. This design suite offers an important step toward systematic incorporation of origami design concepts into new, novel and reconfigurable engineering devices. [Preview Abstract] |
Monday, March 2, 2015 10:12AM - 10:24AM |
A44.00010: Origami folding of polymer sheets by inkjet printing Ying Liu, Brandi Shaw, Michael D. Dickey, Jan Genzer In analogy to the ancient Japanese art of paper folding (Origami), self-folding is an attractive strategy to induce the formation of three-dimensional (3D) objects with well-defined shapes and dimensions using conventional two-dimensional (2D) patterning techniques, such as lithography and inkjet printing. Self-folding can be applied in the areas of reconfigurable devices, actuators, and sensors. Here we demonstrate a simple method for self-folding of polymer sheets utilizing localized light absorption on selected areas of the pre-strained polymer sheet. The ink is patterned via a desktop printer and it defines the location of the `hinge' on the sheet. The inked areas on the 2D sheet absorb light preferentially, thus causing the polymer sheet to fold locally in the inked areas. The temperature gradients through the depth of the sheet induce localized shrinkage and the sheet folds within seconds. This patterned polymer sheets act as shape memory materials which can be programmed to fold into various 3D structures based on the nature of the light source, the shape and size of the ink patterns, and ink property. By controlling the aforementioned parameters we achieve a complete control of the time and degree of folding, which ultimately govern the final 3D shape of the folded object. [Preview Abstract] |
Monday, March 2, 2015 10:24AM - 10:36AM |
A44.00011: Actuated 3D origami-like structures with tunable volume and stiffness Johannes Overvelde, Twan de Jong, James Weaver, Chuck Hoberman, Katia Bertoldi Recent years have seen an uprise of new materials with interesting and unusual properties that result from their regular periodic microstructure. Origami-based metamaterials based on the Miura fold pattern have recently gained a lot of attention for their ability to drastically change their shape and therewith creating a programmable metamaterial. In this work, we propose a completely new class of actuated 3D foldable materials with three degrees of freedom that can drastically change their shape and volume by folding. These materials do not only change their shape, but also have a tunable stiffness that can vary two orders of magnitude by making use of contact interaction between different parts of the material. We experimentally show their effectiveness by building a metamaterial consisting of 64 unit cells and by incorporating local inflatable actuators in the material to enable large on demand changes in shape and stiffness. [Preview Abstract] |
Monday, March 2, 2015 10:36AM - 10:48AM |
A44.00012: Stress Focusing in Creased Shells Sarah Selden, Arthur Evans, Nakul Bende, Ryan Hayward, Christian Santangelo Upon indentation, thin shells react by localizing strain energy in polygonal structures as opposed to a uniform axisymmetric distribution. While the formation of these localized structures are well-characterized for perfect shells, the introduction of a crease fundamentally changes the nature of the shell deformation. We perform finite element simulations, in tandem with experiments to explore the effect of a creased shell on the energy landscape. We find that the crease induces a new symmetry-breaking localization that does not appear in perfect shells, and we explore the deformation characteristics of the creased shell over a wide range of crease sizes, shell thickness, and crease orientations. [Preview Abstract] |
Monday, March 2, 2015 10:48AM - 11:00AM |
A44.00013: Folding and bending of self-assembled nanoparticle membranes Yifan Wang, Jianhui Liao, Sean Mcbride, Efi Efrati, Xiao-Min Lin, Heinrich Jaeger We demonstrate that self-assembled nanoparticle monolayers can be folded into 3 dimensional hollow structures -- nanoparticle scrolls, by utilizing their internal strain gradient. Using an Atomic Force Microscope (AFM), indentation measurements were made on these nanoparticle scrolls, and the bending modulus of the nanoparticle membrane is obtained for the first time. The resulting bending modulus is two orders of magnitude larger than that predicted by classical continuum elastic theory, we show this can be explained by a micropolar theory as the material thickness approaches single nanoparticle size. [Preview Abstract] |
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