Overcurvature induced multistability of linked conical frusta: how a ‘bendy straw’ holds its shape

Bende, Nakul; Yu, Tian; Corbin, Nicholas; Dias, Marcelo A.; Santangelo, Christian; Hanna, James; Hayward, Ryan C.

doi:10.1039/c8sm01355a

Cited by 24 publications

(15 citation statements)

References 32 publications

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“…The design has the ability to store potential energy in the bending of the folds and the stretching of the faces, similarly to the multistable "bendy straw" design [27]. Interestingly, by changing the size of the design and geometric parameters such as β and ∆z, the amount of structural deformation required for the design to bend and compress can be manipulated, thus allowing us to control the stiffness of the design purely through its geometry.…”

Section: A Parameterized Programmable Crease Patternmentioning

confidence: 99%

A Programmably Compliant Origami Mechanism for Dynamically Dexterous Robots

Chen

Misra

Gao

et al. 2020

IEEE Robot. Autom. Lett.

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We present an approach to overcoming challenges in dynamical dexterity for robots through tunable origami structures. Our work leverages a one-parameter family of flat sheet crease patterns that folds into origami bellows, whose axial compliance can be tuned to select desired stiffness. Concentrically arranged cylinder pairs reliably manifest additive stiffness, extending the tunable range by nearly an order of magnitude and achieving bulk axial stiffness spanning 200-1500 N m −1 using 8 mil thick polyester-coated paper. Accordingly, we design origami energy-storing springs with a stiffness of 1035 N m −1 each and incorporate them into a three degree-offreedom (DOF) tendon-driven spatial pointing mechanism that exhibits trajectory tracking accuracy less than 15% rms error within a (∼2 cm) 3 volume. The origami springs can sustain high power throughput, enabling the robot to achieve asymptotically stable juggling for both highly elastic (1 kg resilient shotput ball) and highly damped ("medicine ball") collisions in the vertical direction with apex heights approaching 10 cm. The results demonstrate that "soft" robotic mechanisms are able to perform a controlled, dynamically actuated task.

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Section: A Parameterized Programmable Crease Patternmentioning

confidence: 99%

A Programmably Compliant Origami Mechanism for Dynamically Dexterous Robots

Chen

Misra

Gao

et al. 2020

IEEE Robot. Autom. Lett.

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“…The original bendy straw cell has been described as a pair of conical frusta [12]. Bendy straws can be described in terms of the following parameters: R, the external radius of the cell, the ratio r = r R between the internal and external radii, and a 1 and a 2 , the angles of the top and bottom conical frusta.…”

Section: Geometry and Parametrizationmentioning

confidence: 99%

“…It is worth noting that bistability and even multistability can also be observed in soft structures such as the common bendy straw, which can be either bistable or multistable as required [12]. This was the starting point of our study on the design and construction of a multistable origami tube.…”

Section: Introductionmentioning

confidence: 98%

“…This bendy straw structure consisting of non-identical conical frusta can easily be made to become axially bistable, which means that it can adopt two different states: a tall stable state and a compressed state in which its smallest frustum is inverted. It is also possible to add another stable state: when the structure has some built-in stress, its frustum can become partially inverted, giving the structure a bent shape, the direction of which can be continuously varied while maintaining the bent state [12].…”

Section: Introductionmentioning

confidence: 99%

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Design of an Origami Bendy Straw for Robotic Multistable Structures

Bernardes

Viollet

2021

Journal of Mechanical Design

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This paper presents a soft cylindrical multi-stable origami structure based on “bendy straws”, consisting of multiple conical frusta mimicking the structure of a flexible drinking straw. These frusta are connected in such a way that the whole structure is axially multi-stable, having a stable compressed state in which its smallest frustum is collapsed. The bendy straw structure can also be modified so that the smallest frustum collapses only partially, keeping the structure in a bent state. We studied the geometry of a similar structure consisting of polygonal frusta instead of conical ones, and used this geometry to design a non-rigidly foldable origami pattern folding into a similar origami bendy straw structure. Most of the origami structures presented so far have been modeled from rigidly foldable origami patterns: these origami structures do not rely on deformation, and cannot use it to their advantage; whereas the non-rigid origami structure presented here features multi-stability. We have established that this origami structure is not only axially multi-stable, but that it can also be kept in a bent state, thanks to the use of pop-through defects (PTDs). The origami bendy straws studied here were made from paper (with a density of 90g/m2) bi-laminated with a 42.5-micron thick plastic film. A digital dynamometer was used to study the forces required to compress and expand a single origami bendy straw, create and reverse a PTD, and bend an origami bendy straw using PTDs.

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“…1(a), the unit cell structure of such a flexible straw is a pair of intersecting conical frustra (the outer frustum, Q-T-P and the inner one, Q-P, intersecting at the folds P and Q). By designing the geometrical parameters of the unit cell, a recent study [45] has demonstrated that both the axially folded state and the extended state can be mechanically stable (Figs. 1(b) and 1(c)) for elastic shells.…”

Section: Unit Cell Designmentioning

confidence: 99%

Engineer Energy Dissipation in 3D Graphene Nanolattice Via Reversible Snap-Through Instability

Gao²

2019

Journal of Applied Mechanics

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Carbon micro/nanolattice materials, defined as three-dimensional (3D) architected metamaterials made of micro/nanoscale carbon constituents, have demonstrated exceptional mechanical properties, including ultrahigh specific strength, stiffness, and extensive deformability through experiments and simulations. The ductility of these carbon micro/nanolattices is also important for robust performance. In this work, we present a novel design of using reversible snap-through instability to engineer energy dissipation in 3D graphene nanolattices. Inspired by the shell structure of flexible straws, we construct a type of graphene counterpart via topological design and demonstrate its associated snap-through instability through molecular dynamics (MD) simulations. One-dimensional (1D) straw-like carbon nanotube (SCNT) and 3D graphene nanolattices are constructed from a unit cell. These graphene nanolattices possess multiple stable states and are elastically reconfigurable. A theoretical model of the 1D bi-stable element chain is adopted to understand the collective deformation behavior of the nanolattice. Reversible pseudoplastic behavior with a finite hysteresis loop is predicted and further validated via MD. Enhanced by these novel energy dissipation mechanisms, the 3D graphene nanolattice shows good tolerance of crack-like flaws and is predicted to approach a specific energy dissipation of 233 kJ/kg in a loading cycle with no permanent damage (one order higher than the energy absorbed by carbon steel at failure, 16 kJ/kg). This study provides a novel mechanism for 3D carbon nanolattice to dissipate energy with no accumulative damage and improve resistance to fracture, broadening the promising application of 3D carbon in energy absorption and programmable materials.

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Overcurvature induced multistability of linked conical frusta: how a ‘bendy straw’ holds its shape

Cited by 24 publications

References 32 publications

A Programmably Compliant Origami Mechanism for Dynamically Dexterous Robots

A Programmably Compliant Origami Mechanism for Dynamically Dexterous Robots

Design of an Origami Bendy Straw for Robotic Multistable Structures

Engineer Energy Dissipation in 3D Graphene Nanolattice Via Reversible Snap-Through Instability

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