Tailorable Stiffness Lightweight Soft Robotic Materials with Architectured Exoskeleton

Ali, Hessein; Ebrahimi, Hossein; Stephen, Jeremy; Warren, Peter; Ghosh, Ranajay

doi:10.2514/6.2020-1551

Cited by 5 publications

(5 citation statements)

References 12 publications

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“…In this context, characterizing bending and twisting plays an important role in ascertaining the benefits of these structures. Prior research has shown that bending and twisting of a scale-covered substrate show small-strain reversible nonlinear stiffening and locking behavior, due to the sliding kinematics of the scales embedded in the substrates [1][2][3][4][5][6][41][42][43][44][45]. Such sliding interlocking structures possess certain unique characteristics, which give biological structures advantages without sophisticated parent materials.…”

Section: Introductionmentioning

confidence: 99%

Coulomb friction in twisting of biomimetic scale-covered substrate

2020

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Biomimetic scale-covered substrates provide geometric tailorability via scale orientation, spacing and also interfacial properties of contact in various deformation modes. No work has investigated the effect of friction in twisting deformation of biomimetic scale-covered beams. In this work, we investigate the frictional effects in the biomimetic scale-covered structure by developing an analytical model verified by finite element simulations. In this model, we consider dry (Coulomb) friction between rigid scales surfaces, and the substrate as the linear elastic rectangular beam. The obtained results show that the friction has a dual contribution on the system by advancing the locking mechanism due to change of mechanism from purely kinematic to interfacial behavior, and stiffening the twist response due to sharp increase in the engagement forces. We also discovered, by increasing the coefficient of friction potentially using engineering scale surfaces to a critical coefficient, the system could reach to instantaneous post-engagement locking. The developed model outlines analytical relationships between geometry, deformation, frictional force and strain energy, to design biomimetic scale-covered metamaterials for a wide range of applications.

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Section: Introductionmentioning

confidence: 99%

Coulomb friction in twisting of biomimetic scale-covered substrate

2020

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“…It is here that characterizing bending and twisting play an important role in ascertaining the benefit of these structures. Prior research has shown that bending and twisting of a substrate show small strain reversible nonlinear stiffening and locking behavior due to the sliding kinematics of the scales in one-dimensional substrates [29][30][31][32][33][34][35][36][37][38][39]. The universality of these behavior across bending of uniformly distributed scales, functionally graded scales and uniformly distributed twisting is an important discovery.…”

Section: Introductionmentioning

confidence: 99%

Tailorable twisting of biomimetic scale-covered substrate

Ebrahimi¹,

Ali²,

Galvez³

et al. 2019

EPL

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Biomimetic scale-covered substrates provide geometric tailorability via scale orientation, spacing and also interfacial properties of contact in various deformation modes. No work has investigated the effect of friction in twisting deformation of biomimetic scale-covered beams. In this work, we investigate the frictional effects in the biomimetic scale-covered structure by developing an analytical model verified by the finite element simulations. In this model, we consider dry (Coulomb) friction between rigid scales surfaces, and the substrate as the linear elastic rectangular beam. The obtained results show that the friction has a dual contribution on the system by advancing the locking mechanism due to change of mechanism from purely kinematic to interfacial behavior, and stiffening the twist response due to increase the engagement forces. We also discovered, by increasing the coefficient of friction using engineering scale surfaces to a critical coefficient, the system could reach to an instantaneous post-engagement locking. The developed model outlines analytical relationships between geometry, deformation, frictional force and kinematic energy, to design biomimetic scale-covered metamaterials for a wide range of application.

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“…Thus, they are now intensely studied as material templates to make armors, smart skins, soft robotics and multifunctional surfaces [10][11][12][13]. Mechanically, scales give rise to fascinating emergent behavior such as strain stiffening, evolving directionality and anomalous frictional response [14][15][16][17][18][19][20][21][22][23][24]. These behaviors can potentially aid organisms in balancing multiple complex and often contradictory functions such as locomotion with protection, and softness with stiffness.…”

Section: Introductionmentioning

confidence: 99%

Coupled Bend-Twist Mechanics of Biomimetic Scale Substrate

Dharmavaram,

Ebrahimi,

Ghosh

2021

Preprint

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We develop the mechanics of combined bending and twisting deformation of a onedimensional filamentous structure with protruding stiff fish-scale-like plates embedded at an angle on the surface. We develop Cosserat kinematic formulation along with scale contact constraints. This geometrically exact model allows us to bypass the limitations of typical finite element computations inherent in these systems when deflections are large. The derived structure-property relationships reveal for the first time the combined effect of bending and twisting on a slender fish scale inspired substrate. The model subsumes previous models on pure bending and twisting but also shows previously unobserved phenomena that arise due to the coupled effects of these loads. This includes a new interpretation of kinematic locking behavior, multiple contact regimes, asymmetric sensitivities of one curvature over the other, and sharp transitions in the nonlinear moment-curvature and torque-twist behaviors reflecting the complex scale engagement patterns.

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Tailorable Stiffness Lightweight Soft Robotic Materials with Architectured Exoskeleton

Cited by 5 publications

References 12 publications

Coulomb friction in twisting of biomimetic scale-covered substrate

Coulomb friction in twisting of biomimetic scale-covered substrate

Tailorable twisting of biomimetic scale-covered substrate

Coupled Bend-Twist Mechanics of Biomimetic Scale Substrate

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