Tailorable twisting of biomimetic scale-covered substrate

Ebrahimi, Hossein; Ali, Hessein; Galvez, Jonathan; Gordon, Ali P.; Ghosh, Ranajay

doi:10.1209/0295-5075/127/24002

Cited by 15 publications

(58 citation statements)

References 65 publications

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“…Scales embedding itself will lead to increase in stiffness. This effect is however, distinct and already investigated in some detail in literature 15 , including a comparison with the scales engagement (sliding effect) 12,19 . The effect of pure embedding is primarily a composite effect and measurable even before engagement.…”

Section: Resultsmentioning

confidence: 77%

“…The parameters affecting the bending deformation modes are relative stiffnesses of the scales and the substrate, scales overlap ratios, length, contact friction and some other geometrical parameters discussed in previous studies [16][17][18] . These nonlinear regimes are more universal than pure bending and also reported in non-uniform loads as well as torsion 16,19,20 . Thus clearly, changing the scales properties can lead to a change in the overall behavior of the structure.…”

Section: Bending Behavior Of Biomimetic Scale Covered Beam With Tunabmentioning

confidence: 76%

“…The effect of pure embedding is primarily a composite effect and measurable even before engagement. The effects of engagement are clearly visible by sharp increases in stiffness which is not the case with only inclusions 12,19 . It may be possible to fabricate the tunable stiffness scales of scale covered systems using alternative ways by making embedded channels of LMPAs enabling direct joule heating of individual scales.…”

Section: Resultsmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 96%

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Bending behavior of biomimetic scale covered beam with tunable stiffness scales

Tatari

Kamrava

Ghosh

et al. 2020

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Biomimetic scales provide a convenient template to tailor the bending stiffness of the underlying slender substrate due to their mutual sliding after engagement. Scale stiffness can therefore directly impact the substrate behavior, opening a potential avenue for substrate stiffness tunability. Here, we have developed a biomimetic beam, which is covered by tunable stiffness scales. Scale tunability is achieved by specially designed plate like scales consisting of layers of low melting point alloy (LMPA) phase change materials fully enclosed inside a soft polymer. These composite scales can transition between stiff and soft states by straddling the temperatures across LMPA melting points thereby drastically altering stiffness. We experimentally analyze the bending behavior of biomimetic beams covered with tunable stiffness scales of two architectures—one with single enclosure of LMPA and one with two enclosures of different melting point LMPAs. These architectures provide a continuous stiffness change of the underlying substrate post engagement, controlled by the operating temperature. We characterize this response using three-point bending experiments at various temperature profiles. Our results demonstrate for the first time, the pronounced and reversible tunability in the bending behavior of biomimetic scale covered beam, which are strongly dependent on the scale material and architecture. Particularly, it is shown that the bending stiffness of the biomimetic scale covered beam can be actively and reversibly tuned by a factor of up to 7. The developed biomimetic beam has applications in soft robotic grippers, smart segmented armors, deployable structures and soft swimming robots.

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Section: Resultsmentioning

confidence: 77%

Section: Bending Behavior Of Biomimetic Scale Covered Beam With Tunabmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 96%

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Bending behavior of biomimetic scale covered beam with tunable stiffness scales

Tatari

Kamrava

Ghosh

et al. 2020

Sci Rep

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“…loading such as armor applications [50] as well as fostering nonlinearities in global deformations in bending and twisting stemming from scales engagement [48,51,52,53,54,55,56,57]. In these studies, the uniformly distributed scales are considered.…”

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confidence: 99%

Tailorable elasticity of cantilever using spatio-angular functionally graded biomimetic scales

2019

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Cantilevered beams are of immense importance as structural and sensorial members for a number of applications. Endowing tailorable elasticity can have wide ranging engineering ramification. Such tailorability could be possible using some type of spatial gradation in the beams material or cross section. However, these often require extensive additive and subtractive material processing or specialized casts. In this letter, we demonstrate an alternative bio inspired mechanical pathway, which is based on exploiting the nonlinearity that would arise from a functionally graded distribution of biomimetic scales on the surface using an analytical approach. This functional gradation is geometrically sourced and could arise from either spatial or angular gradation of scales. We analyze such a functionally graded cantilever beam under uniform loading. In comparison with uniformly distributed scales, we find significant differences in bending stiffness for both spatial and angular gradations. Spatial and angular functional gradation share some universality but also sharp contrasts in their effect on the underlying beam. A combination of both types of gradation in the structure can be used to alternatively increase or decrease stiffness and therefore a pathway to tailor the elasticity of a cantilever beam relatively easily. These results give rise to an architected framework for designing and optimizing the topography of leveraged solids.Cantilevered beams arise in a number of diverse engineering applications spanning an enormous variety of length scales [1,2,3,4,5,6,7,8,9,10]. In several of these applications, tailoring elasticity can be of tremendous significance since it can be used to design the response according to stimulus or guard against unwanted instabilities.To this end, functional gradation (FG) is a useful strategy. FG materials are high performance composite materials consisting of two or more constituent phases with variegation in composition. This gradation can lead to a desired enhancement in the thermal/mechanical properties, compared to their conventional counterparts. This makes them ideal for various engineering applications including biomedical [11,12], cellular structures [13,14,15,16,17,18], soft robotics [19,20] and several others [21,22].However, typical FG materials could be difficult to fabricate requiring extensive materials processing such as directional solidification [23], specialized machining paths or even additive manufacturing [23,24]. An alternative exists in pursuing surface based strategy such as biomimetic scales. Such dermal scales are a pervasive feature within Kingdom Animalia. Their advantages extend well into a variety of important functions, which enhance survivability, such as protection, camouflaging, and locomotion [25,26,27,28,29]. In nature, certain fishes possess remarkably periodic scale distribution, for instance, Elasmobranchs [30,31] and Teleosts [32,33,34,35]. However, more often, organisms display a large variation in scale distribution within their own bodies [36,37,...

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