Rate-dependent adhesion of viscoelastic contacts, Part I: Contact area and contact line velocity within model randomly rough surfaces

Violano, Guido; Chateauminois, A.; Afferrante, L.

doi:10.1016/j.mechmat.2021.103926

Cited by 33 publications

(16 citation statements)

References 29 publications

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“…Such period (identified as stick time in Refs. [6,21,35]) increases with the speed and reaches a maximum at about V = 33.33, above which no further variation is observed.…”

Section: Resultsmentioning

confidence: 88%

“…The adhesive contact between a rigid sphere and a viscoelastic substrate is a problem of scientific and technological interest, as adhesion of soft materials plays a key role in biomedicine [1], soft robotics [2], sensors [3], tapes [4] and printing industries [5]. Moreover, the contact mechanics of soft matter is not yet fully understood, due to its intrinsic viscoelasticity and rate-dependent adhesive features [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…In this model (known as Maugis-Dugdale (MD) model) the work of adhesion is assumed to be ∆γ = σ 0 d 0 , where σ 0 is the maximum force predicted by the Lennard-Jones force law and d 0 is the separation at which the areas under the Dugdale and Lennard-Jones curves match. JKR, DMT and MD theories are derived in quasi-static conditions and, therefore, cannot be applied to viscoelastic solids exhibiting rate-dependent adhesion [6]. Real soft materials, like natural rubbers and synthetic polymers, seldom show a linear elastic constituive behaviour.…”

Section: Introductionmentioning

confidence: 99%

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On the effective surface energy in viscoelastic Hertzian contacts

Afferrante,

Violano

2021

Preprint

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Viscoelasticity and rate-dependent adhesion of soft matter lead to difficulties in modeling the 'relatively simple' problem of a rigid sphere in contact with a viscoelastic half-space. For this reason, approximations in describing surface interactions and viscous dissipation processes are usually adopted in the literature.Here, we develop a fully deterministic model in which adhesive interactions are described by Lennard-Jones potential and the material behaviour with the standard linear solid model.Normal loading-unloading cycles are carried out under different driving conditions. When loading is performed in quasi-static conditions and, hence, unloading starts from a completely relaxed state of the material, the effective surface energy is found to monotonically increase with the contact line velocity up to an asymptotic value reached at high unloading rates. Such result agrees with existing theories on viscoelastic crack propagation.If loading and unloading are performed at the same non-zero driving velocity and, hence, unloading starts from an unrelaxed state of the material, the trend of the effective surface energy ∆γ eff with the contact line velocity is described by a bell-shaped function in a double-logarithmic plot. The peak of ∆γ eff is found at a contact line velocity smaller than that makes maximum the tangent loss of the viscoelastic modulus. Furthermore, we show Gent&Schultz assumption partly works in this case as viscous dissipation is no longer localized along the contact perimeter but it also occurs in the bulk material.

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“…Such period (identified as stick time in Refs. [6,21,35]) increases with the speed and reaches a maximum at about V = 33.33, above which no further variation is observed.…”

Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the effective surface energy in viscoelastic Hertzian contacts

Afferrante,

Violano

2021

Preprint

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“…For details about the experimental setup, the manufacturing of the PDMS samples and the experimental procedure used during indentation tests we refer the reader to Ref. [17].…”

Section: Experimental Set-upmentioning

confidence: 99%

“…In Ref. [17], we experimentally studied the detachment of a rigid indenter from soft PolyDiMethylSiloxane (PDMS) substrates with smooth and rough surface. Specifically, roughness was obtained by texturing the surface with spherical identical micro-asperities with controlled height and spatial distributions.…”

Section: Introductionmentioning

confidence: 99%

Rate-dependent adhesion of viscoelastic contacts. Part II: numerical model and hysteresis dissipation

Violano¹,

Chateauminois²,

Afferrante³

2020

Preprint

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In this paper, we propose a numerical model to describe the adhesive normal contact between a 'rigid' spherical indenter and a viscoelastic rough substrate. The model accounts for dissipative process under the assumption that viscoelastic losses are localized at the (micro)-contact lines.Numerical predictions are then compared with experimental measurements, which show a strong adhesion hysteresis mostly due to viscous energy dissipation occurring during pull-off. This hysteresis is satisfactorily described by the contact model which allows to distinguish the energy loss due to material dissipation from the adhesion hysteresis due to elastic instability.Our analysis shows that the pull-off force required to detach the surfaces is strongly influenced by the detachment rate and the rms roughness amplitude, but it is almost unaffected by the maximum load from which unloading starts. Moreover, the increase in the boundary line separating contact and non-contact regions, observed when moving from smooth to rough contacts, negligibly affects the viscous dissipation. Such increase is much less significant than the reduction in contact area, which therefore is the main parameter governing the strong decrease in the effective surface energy.

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A PDMS/Silicon Adhesion Control Method at Millimeter‐Scale Based on Microvibration

Yi,

Haouas,

Gauthier

et al. 2024

Advanced Intelligent Systems

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Switchable surface adhesion at a small scale is crucial for robot end‐effector design, allowing the manipulation of small objects such as semiconductors, optical lenses, and precision mechanical parts. In this work, a detailed characterization of a millimeter‐scale (1–5 mm) adhesion modulation method is performed, demonstrating its effectiveness for switching adhesion on small, lightweight objects with smooth surfaces. This modulation phenomenon arises from the viscoelastic behavior when PDMS interacts with a rigid surface and is controlled via microvibration. A maximum apparent adhesion enhancement of 2400% and a reduction of 50% are achieved with a 1 mm‐diameter PDMS hemisphere vibrating at a 30 μm amplitude and a 700 Hz frequency. The effects of different parameters, including size, actuation amplitude/frequency, surface roughness, and material properties, on adhesion performance are carefully measured and analyzed. A monotonic increase in maximum adhesion is observed with increased device size and surface smoothness, while nonlinear relationships of other factors are generalized with a numerical model. A long working lifespan and high endurance are also observed during the characterization. This work serves as a practical reference for the further design of small‐scale soft grippers, highlighting its continuous, large modulation range, simple structure, and flexible control.

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Rate-dependent adhesion of viscoelastic contacts, Part I: Contact area and contact line velocity within model randomly rough surfaces

Cited by 33 publications

References 29 publications

On the effective surface energy in viscoelastic Hertzian contacts

On the effective surface energy in viscoelastic Hertzian contacts

Rate-dependent adhesion of viscoelastic contacts. Part II: numerical model and hysteresis dissipation

A PDMS/Silicon Adhesion Control Method at Millimeter‐Scale Based on Microvibration

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