Load sharing in bioinspired fibrillar adhesives with backing layer interactions and interfacial misalignment

Bacca, Mattia; Booth, Jamie A.; Turner, Kimberly L.; McMeeking, Robert M.

doi:10.1016/j.jmps.2016.04.008

Cited by 47 publications

(33 citation statements)

References 36 publications

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“…It is expected that also arrays of funnel-shaped structures will surpass arrays with other geometries although arrays generally tend to show lower adhesion than single microstructures. [26] -Tests under reduced pressure revealed that most probably van der Waals interactions contribute to the adhesion, while contribution of suction and capillarity plays only a minor role. -The flexibility of the flaps provides high compliance during contact formation that helps to accommodate surface irregularities and even small misalignments between the structure and the substrate.…”

Section: Resultsmentioning

confidence: 93%

“…[20,21] In practice, however, these stresses are typically in the range of several hundreds of kilopascals or below. [22][23][24][25] The discrepancy is most likely caused by nonideal contact and detachment conditions: possible causes are, besides surface roughness, unequal load sharing, [26] or flaws and local stress concentrations. [27][28][29][30] Therefore, tailoring the stress distribution along the fibril-substrate interface by reducing such stress concentrations is a major objective in fabricating synthetic fibrillar dry adhesives with high pull-off stresses.…”

Section: Introductionmentioning

confidence: 99%

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Funnel‐Shaped Microstructures for Strong Reversible Adhesion

Fischer

Groß

Abad

et al. 2017

Adv Materials Inter

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The potential of a new design of adhesive microstructures in the micrometer range for enhanced dry adhesion is investigated. Using a two‐photon lithography system, complex 3D master structures of funnel‐shaped microstructures are fabricated for replication into poly(ethylene glycol) dimethacrylate polymer. The diameter, the flap thickness, and the opening angle of the structures are varied systematically. The adhesion of single structures is characterized using a triboindenter system equipped with a flat diamond punch. The pull‐off stresses obtained reaches values up to 5.6 MPa, which is higher than any values reported in literature for artificial dry adhesives. Experimental and numerical results suggest a characteristic attachment mechanism that leads to intimate contact formation from the edges toward the center of the structures. van der Waals interactions most likely dominate the adhesion, while contributions by suction or capillarity play only a minor role. Funnel‐shaped microstructures are a promising concept for strong and reversible adhesives, applicable in novel pick and place handling systems or wall‐walking robots.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Funnel‐Shaped Microstructures for Strong Reversible Adhesion

Fischer

Groß

Abad

et al. 2017

Adv Materials Inter

View full text Add to dashboard Cite

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“…If the correct levels of spatial-tailoring (both properties and scale) in the bondlayer can be achieved, for example, in structural composite adhesive joining, performance may approach what some have called optimal design of such interfaces by bio-mimicking. [33,[51][52][53][54][55][56][57][58] While the tailoring considered here imparts large improvements to the multilayer, even a small design improvement of such joints in application can lead to large benefits, for example, the 2017 GMC Acadia sport utility vehicle is 700 pounds lighter than the version it replaced, contributing a 28% improvement in gas mileage, due primarily to the use of improved joining materials. [48] Compliance-tailoring of the bondlayer is an additional and facile approach to improving joint performance in both short and long, relative to critical shear transfer length, bonding applications.…”

Section: Discussionmentioning

confidence: 99%

Stress Reduction of 3D Printed Compliance‐Tailored Multilayers

et al. 2017

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Multilayered multi-material interfaces are encountered in an array of fields. Here, enhanced mechanical performance of such multi-material interfaces is demonstrated, focusing on strength and stiffness, by employing bondlayers with spatially-tuned elastic properties realized via 3D printing. Compliance of the bondlayer is varied along the bondlength with increased compliance at the ends to relieve stress concentrations. Experimental testing to failure of a tri-layered assembly in a single-lap joint configuration, including optical strain mapping, reveals that the stress and strain redistribution of the compliance-tailored bondlayer increases strength by 100% and toughness by 60%, compared to a constant modulus bondlayer, while maintaining the stiffness of the joint with the homogeneous stiff bondlayer. Analyses show that the stress concentrations for both peel and shear stress in the bondlayer have a global minimum when the compliant bond at the lap end comprises %10% of the bondlength, and further that increased multilayer performance also holds for long (relative to critical shear transfer length) bondlengths. Damage and failure resistance of multi-material interfaces can be improved substantially via the compliance-tailoring demonstrated here, with immediate relevance in additive manufacturing joining applications, and shows promise for generalized joining applications including adhesive bonding.

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“…Over the last few years, several analytical models have been proposed to provide for understanding of adhesive behavior of microcontacts of a cluster structure [9][10][11]. A detailed review can be found in [12].…”

Section: Figmentioning

confidence: 99%

Adhesive Force of Flat Indenters With Brush-Structure

Popov

2018

FU Mech Eng

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Abstract. We have numerically studied adhesive contact between a flat indenter with brush structure and an elastic half space using the boundary element method. Various surface structures with different size, number and shape of the "pillars", as well as their distributions (regular or random) have been investigated. The results validate the theoretical prediction that the adhesive force in contact of an indenter with discontinuous areas is roughly proportional to the square root of the real contact density ("filling factor").

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Load sharing in bioinspired fibrillar adhesives with backing layer interactions and interfacial misalignment

Cited by 47 publications

References 36 publications

Funnel‐Shaped Microstructures for Strong Reversible Adhesion

Funnel‐Shaped Microstructures for Strong Reversible Adhesion

Stress Reduction of 3D Printed Compliance‐Tailored Multilayers

Adhesive Force of Flat Indenters With Brush-Structure

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