Phase-transforming and switchable metamaterials

Yang, Dian; Jin, Lihua; Martínez, Ramsés V.; Bertoldi, Katia; Whitesides, George M.; Suo, Zhigang

doi:10.1016/j.eml.2015.11.004

Cited by 87 publications

(38 citation statements)

References 29 publications

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“…These attributes offer motivation to develop material systems that may emulate such characteristics. Many efforts in this spirit have sought to mimic whole-muscle morphology and behaviors, leading to significant progress in fields such as soft actuators [1][2][3][4][5], legged robotics [6][7][8], and electroactive polymers and hydrogels [9][10][11][12]. On the other hand, various advantageous characteristics of skeletal muscle have origins in the nanoscale constituents that comprise the actomyosin network [13].…”

Section: Introductionmentioning

confidence: 99%

Modular and programmable material systems drawing from the architecture of skeletal muscle

2018

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The passive attributes of skeletal muscle "material" often have origins in nanoscale architecture and functionality where geometric frustrations directly influence macroscale mechanical properties. Drawing from concepts of the actomyosin network, this study investigates a modular, architected material system that leverages spatial constraints to generate multiple stable material topologies and to yield large adaptability of material mechanical properties. By exploiting the shearing actions induced on an actomyosin-inspired assembly of modular material constituents, new intriguing material behaviors are cultivated, including strong metastability and energy-releasing state transitions. Experimental, numerical, and analytical studies reveal that such passive attributes can be tailored by geometric constraints imposed on the modular material system. The geometric parameters can also introduce a bias to the deformations, enabling a programmable response. By invoking the spatial constraints and oblique, shear-like motions inherent to skeletal muscle architecture, this research illustrates new potential for architected material systems that exploit locally tunable properties to achieve targeted macroscopic behaviors.

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Section: Introductionmentioning

confidence: 99%

Modular and programmable material systems drawing from the architecture of skeletal muscle

2018

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“…Compressive stress, geometric constraint, and active multi‐field tuning are candidate methods for sustaining material systems near phase transitions. We capitalize on a passive, geometric constraint applied to an architected elastomer material inclusion, Figure b and c. The rotationally symmetric, radially arrayed beam geometry, outlined in the dashed line in Figure b and c, is inspired by recent work on post‐buckled metamaterials .…”

mentioning

confidence: 99%

Resilience to Impact by Extreme Energy Absorption in Lightweight Material Inclusions Constrained Near a Critical Point

et al. 2016

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This work investigates a model design for lightweight, architected material inclusions that cultivate significant impact energy dissipation in structures. The inclusions are sustained near a critical point where damping is theoretically increased without bound. Using the principle, a material architecture and constraint mechanism are studied that exemplify the theory. Guided by a computational model and analysis, numerous specimens are fabricated and experimentation verifies that engineered material inclusions constrained nearer to critical points most effectively suppress structural dynamics following impact, minimize transmitted impulsive force, and better promote structural integrity. The concepts articulated here may find broad application for reusable, resilient protective structures.

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“…In other words, it is possible to tune the mechanical response of a material by controlling its architecture. Mechanical metamaterials illustrate this close relationship between architecture and functionality by exhibiting unusual physical properties such as negative Poisson's ratio, multistability, phase shifting, or programmability . The structure of most mechanical metamaterials previously reported consist of periodic arrays of unit cells, which lead to materials with uniform mechanical responses upon actuation.…”

Section: Introductionmentioning

confidence: 99%

“…Harnessing mechanical instabilities—considered signs of structural failure in hard actuators—has recently emerged as a robust strategy to design and fabricate functional soft actuators with highly controllable nonlinear behavior . The reversible buckling of elastomeric beams is an example of a mechanical instability that can be harnessed to enable applications in stretchable electronics, switchable metamaterials, and soft fluidic actuators . Fluidic, buckling‐based soft actuators typically consist of an elastomeric slab patterned with 2D periodic arrays of holes perpendicular to the slab sealed by elastomeric membranes .…”

Section: Introductionmentioning

confidence: 99%

3D‐Architected Soft Machines with Topologically Encoded Motion

Goswami

Liu

Pal

et al. 2019

Adv Funct Materials

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The limited range of mechanical responses achievable by materials compatible with additive manufacturing hinders the 3D printing of continuum soft robots with programmed motion. This paper describes the rapid design and fabrication of low-density, 3D-architected soft machines (ASMs) by combining Voronoi tessellation and additive manufacturing. On tendon-based actuation, ASMs deform according to the topologically encoded buckling of their structure to produce a wide range of motions (contraction, twisting, bending, and cyclic motion). ASMs exhibiting densities as low as 0.094 g cm −3 (≈8% of bulk polymer) can be rapidly built by the stereolithographic 3D printing of flexible photopolymers or the injection molding of elastomers. The buckling of ASMs can be programmed by inducing gradients in the thickness of their flexible beams or by the localized enlargement of the Voronoi cells to generate complex motions such as multi-finger gripping or quadrupedal locomotion. The topological architecture of these low-density soft robots confers them with the stiffness necessary to recover their original shape even after ultrahigh compression (400%) and extension (500%). ASMs expand the range of mechanical properties currently achievable by 3D printed or molded materials to enable the fabrication of soft machines with auxetic mechanical metamaterial properties.

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Phase-transforming and switchable metamaterials

Cited by 87 publications

References 29 publications

Modular and programmable material systems drawing from the architecture of skeletal muscle

Modular and programmable material systems drawing from the architecture of skeletal muscle

Resilience to Impact by Extreme Energy Absorption in Lightweight Material Inclusions Constrained Near a Critical Point

3D‐Architected Soft Machines with Topologically Encoded Motion

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