Adhesion of compliant spheres: an experimental investigation

Violano, Guido; Afferrante, L.

doi:10.1016/j.prostr.2020.02.022

Cited by 17 publications

(15 citation statements)

References 28 publications

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“…where t = − √ 3/m 4 k m , being k m ∈ (0, ∞) the surface's mean curvature at the apex of an asperity, and the constants C 1 = α/(2α − 3) and C 2 = C 1 √ 12/α are related to the Nayak parameter α = m 0 m 4 /m 2 2 . The quantities m 0 , m 2 , and m 4 are the spectral moments of surface roughness PSD.…”

Section: Discussionmentioning

confidence: 99%

“…When the rough surface approaches the half-space, a new contact is formed when the gap between an asperity and the half-space becomes smaller than δ in , which is calculated for each asperity. A first estimate of the asperity contact radius a i is done by inverting the JKR relation (2). Then, after a further increment of the approach ∆δ i = z i − w i , being z i the height of the asperity i, the contact radius is increased by the quantity…”

Section: Adhesion Hysteresis Of Rough Elastic Surfacesmentioning

confidence: 99%

“…which is obtained by differentiating Equation (2). The total contact area and load are then obtained by summing up the contributions of all the asperities in contact.…”

Section: Adhesion Hysteresis Of Rough Elastic Surfacesmentioning

confidence: 99%

“…Its origin may be related to various phenomena occurring at the contact interface. The main causes of hysteresis are viscoelasticity [1,2], plasticity [3], adhesive elastic instabilities at jump-in and jump-out of contact [4], and surface roughness [5]. In particular, all natural and artificial surfaces are rough at some scale.…”

Section: Introductionmentioning

confidence: 99%

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Roughness-Induced Adhesive Hysteresis in Self-Affine Fractal Surfaces

Violano

Afferrante

2021

Lubricants

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It is known that in the presence of surface roughness, adhesion can lead to distinct paths of loading and unloading for the area–load and penetration–load relationships, thus causing hysteretic loss. Here, we investigate the effects that the surface roughness parameters have on such adhesive hysteresis loss. We focus on the frictionless normal contact between soft elastic bodies and, for this reason, we model adhesion according to Johnson, Kendall, and Roberts (JKR) theory. Hysteretic energy loss is found to increase linearly with the true area of contact, while the detachment force is negligibly influenced by the maximum applied load reached at the end of the loading phase. Moreover, for the micrometric roughness amplitude hrms considered in the present work, adhesion hysteresis is found to be affected by the shorter wavelengths of roughness. Specifically, hysteresis losses decrease with increasing fractal dimension and cut-off frequency of the roughness spectrum. However, we stress that a different behavior could occur in other ranges of roughness amplitude.

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Section: Discussionmentioning

confidence: 99%

Section: Adhesion Hysteresis Of Rough Elastic Surfacesmentioning

confidence: 99%

“…which is obtained by differentiating Equation (2). The total contact area and load are then obtained by summing up the contributions of all the asperities in contact.…”

Section: Adhesion Hysteresis Of Rough Elastic Surfacesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Roughness-Induced Adhesive Hysteresis in Self-Affine Fractal Surfaces

Violano

Afferrante

2021

Lubricants

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“…Velocity-induced increase of adhesion may be observed when detaching two viscoelastic media, due to their rate-dependent behavior (Baek et al, 2017(Baek et al, , 2018Violano and Afferrante, 2019a). Adhesion is of paramount importance in several applications.…”

Section: Introductionmentioning

confidence: 99%

A JKR-Like Solution for Viscoelastic Adhesive Contacts

2021

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A closed-form solution for the adhesive contact of soft spheres of linear elastic material is available since 1971 thanks to the work of Johnson, Kendall, and Roberts (JKR). A similar solution for viscoelastic spheres is still missing, though semi-analytical and numerical models are available today. In this note, we propose a closed-form analytical solution, based on JKR theory, for the detachment of a rigid sphere from a viscoelastic substrate. The solution returns the applied load and contact penetration as functions of the contact radius and correctly captures the velocity-dependent nature of the viscoelastic pull-off. Moreover, a simple approach is provided to estimate the stick time, i.e., the delay between the time the sphere starts raising from the substrate and the time the contact radius starts reducing. A simple formula is also suggested for the viscoelastic pull-off force. Finally, a comparison with experimental and numerical data is shown.

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