Adhesive contact and kinetics of adherence between a rigid sphere and an elastomeric solid

Adhesive contact of a rigid sphere with a layered medium consisting of a stiff elastic layer perfectly bonded to an elastic-plastic substrate is examined in the context of finite element simulations. Surface adhesion is modeled by nonlinear spring elements obeying a force-displacement relation governed by the Lennard–Jones potential. Adhesive contact is interpreted in terms of the layer thickness, effective Tabor parameter (a function of the layer thickness and Tabor parameters corresponding to layer and substrate material properties), maximum surface separation, layer-to-substrate elastic modulus ratio, and plasticity parameter (a characteristic adhesive stress expressed as the ratio of the work of adhesion to the surface equilibrium distance, divided by the yield strength of the substrate). It is shown that surface separation (detachment) during unloading is not encountered at the instant of maximum adhesion (pull-off) force, but as the layered medium is stretched by the rigid sphere, when abrupt surface separation (jump-out) occurs under a smaller force (surface separation force). Ductile- and brittle-like modes of surface detachment, characterized by the formation of a neck between the rigid sphere and the layered medium and a residual impression on the unloaded layered medium, respectively, are interpreted for a wide range of plasticity parameter and maximum surface separation. Numerical results illustrate the effects of layer thickness, bulk and surface material properties, and maximum surface separation (interaction distance) on the pull-off and surface separation forces, jump-in and jump-out contact instabilities, and evolution of substrate plasticity during loading and unloading. Simulations of cyclic adhesive contact demonstrate that incremental plasticity (ratcheting) in the substrate is the most likely steady-state deformation mechanism under repetitive adhesive contact conditions.

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A Continuum Mechanics Model of Adhesive Contact Based on the Lennard-Jones Potential

STLE/ASME 2010 International Joint Tribology Conference ◽

10.1115/ijtc2010-41154 ◽

2010 ◽

Author(s):

Z. Song ◽

K. Komvopoulos

Keyword(s):

Finite Element ◽

Half Space ◽

Surface Displacement ◽

Effective Elastic Modulus ◽

Element Model ◽

Adhesive Contact ◽

Surface Interaction ◽

Rigid Sphere ◽

Adhesive Interaction ◽

Lennard Jones

A continuum model of adhesive interaction between elastic surfaces is presented. Surface interaction between two elastic spheres is modeled by the Lennard-Jones (L-J) potential. The analysis is based on the equivalent system of a rigid sphere of reduced radius in close proximity with an elastic half-space of effective elastic modulus. The critical gap at the instant of the “jump-in” and “jump-out” contact instabilities is determined by an elastic solution of the half-space surface displacement. A finite element model, in which surface interaction is modeled by nonlinear springs of a prescribed force-displacement governed by the L-J potential, is also used to analyze adhesive surface interaction. The analytical model is validated by finite element results of the critical central gap at the instant of jumpin and jump-out instabilities for different values of the Tabor parameter.

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Energetic criterion for adhesion in viscoelastic contacts with non-entropic surface interaction

Reports in Mechanical Engineering ◽

10.31181/rme200102057p ◽

2021 ◽

Vol 2 (1) ◽

pp. 57-64

Author(s):

Valentin Popov ◽

Keyword(s):

Energy Balance ◽

Adhesive Contact ◽

Work Of Adhesion ◽

Surface Element ◽

Creep Function ◽

Small Range ◽

Detachment Criterion ◽

The Moment ◽

Kinetics Of ◽

Stored Elastic Energy

We suggest a detachment criterion for a viscoelastic elastomer contact based on Griffith's idea about the energy balance at an infinitesimal advancement of the boundary of an adhesive crack. At the moment of detachment of a surface element at the boundary of an adhesive contact, there is some quick (instant) relaxation of stored elastic energy which can be expressed in terms of the creep function of the material. We argue that it is only this "instant part" of stored energy which is available for doing work of adhesion and thus it is only this part of energy relaxation that must be used in Griffith's energy balance. The described idea has several restrictions. Firstly, in this pure form, it is only valid for adhesive forces having an infinitely small range of action (which we call the JKR-limit). Secondly, it is only applicable to non-entropic (energetic) interfaces, which detach "at once" and do not possess their own kinetics of detachment.

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A JKR-Like Solution for Viscoelastic Adhesive Contacts

Frontiers in Mechanical Engineering ◽

10.3389/fmech.2021.664486 ◽

2021 ◽

Vol 7 ◽

Author(s):

Guido Violano ◽

Antoine Chateauminois ◽

Luciano Afferrante

Keyword(s):

Closed Form ◽

Numerical Models ◽

Closed Form Solution ◽

Numerical Data ◽

Adhesive Contact ◽

Form Solution ◽

Contact Radius ◽

Rigid Sphere ◽

Soft Spheres ◽

Adhesive Contacts

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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Adhesion strength of protective and decorative coatings depending on the porosity of the cement substrate

MATEC Web of Conferences ◽

10.1051/matecconf/202032904001 ◽

2020 ◽

Vol 329 ◽

pp. 04001

Author(s):

Valentina Loganina ◽

Bassam Shareef Denied Al Saedi

Keyword(s):

Bonding Strength ◽

Damage Accumulation ◽

Operating Time ◽

Adhesive Contact ◽

Exponential Dependence ◽

Surface Porosity ◽

Hereditary Factor ◽

Accumulation Of Damage ◽

Kinetics Of

Information provided about long-term bonding strength protective decorative coatings. A method is proposed for assessing the long- term bonding strength of coatings. The method consists in determining the bonding strength before testing and after t hours of testing. The dependence of the long-term bonding strength on the porosity of the cement substrate has been established. With an increase in the surface porosity of the substrate, observed a decrease in the time of maintaining the adhesive contact “coating-substrate». The aging process of coatings is considered from the position accumulation of damage, taking into account the hereditary factor. The influence of the hereditary factor on the kinetics of damage accumulation was established. It is shown that the dependence of the operating time on the level of damage accumulation can be approximated by an exponential dependence. The values of the activation energy of adhesive destruction of coatings are calculated.

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Adhesive contact of a rigid sphere to finitely stretched substrates

Science Bulletin ◽

10.1007/s11434-009-0328-7 ◽

2009 ◽

Vol 54 (11) ◽

pp. 1970-1972 ◽

Cited By ~ 2

Author(s):

LingHui He ◽

KeWei Ding

Keyword(s):

Adhesive Contact ◽

Rigid Sphere

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Effects of strain-dependent surface stress on the adhesive contact of a rigid sphere to a compliant substrate

Soft Matter ◽

10.1039/c8sm02579g ◽

2019 ◽

Vol 15 (10) ◽

pp. 2223-2231 ◽

Cited By ~ 5

Author(s):

Zezhou Liu ◽

Katharine E. Jensen ◽

Qin Xu ◽

Robert W. Style ◽

Eric R. Dufresne ◽

...

Keyword(s):

Finite Element ◽

Large Deformation ◽

Surface Stress ◽

Adhesive Contact ◽

Rigid Sphere ◽

Soft Substrate ◽

Compliant Substrate ◽

Strain Dependent

Finite element is used to simulate the adhesive contact of a rigid sphere on a soft substrate. By including large deformation and strain-dependent surface stress, our prediction agrees much better with experiments, providing support to the existence of strain-dependent surface stress.

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