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Adhesion and fracture; adhesion; contact mechanics; friction;

Roughness-Induced Adhesion

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

Usually, roughness destroys adhesion and this is one of the reasons why the "adhesion paradox", i.e. a "sticky Universe", is not real. However, at least with some special type of roughness, there is even the case of adhesion enhancement, as it was shown clearly by Guduru, who considered the contact between a sphere and a wavy axisymmetric single scale roughness, in the limit of short-range adhesion (JKR limit).

On the Degree of Irreversibility of Friction in Sheared Soft Adhesive Contacts

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

A number of authors have experimentally assessed the influence of friction on adhesive contacts, and generally the contact area has been found to decrease due to tangential shear stresses at the interface. The decrease is however generally much smaller than that predicted already by the Savkoor and Briggs 1977 classical theory using “brittle” fracture mechanics mixed mode model extending the JKR (Griffith like) solution to the contact problem.

Does the loading apparatus stiffness affect the equilibrium of soft adhesive contacts under shear?

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

The interaction between contact area and frictional forces in adhesive soft contacts is receiving much attention in the scientific community due to its implications in many areas of engineering such as surface haptics and bioin-spired adhesives. In this work, we consider a soft adhesive sphere that is pressed against a rigid substrate and is sheared by a tangential force where the loads are transferred to the sphere through a normal and a tangential spring, representing the loading apparatus stiffness.

Elliptical adhesive contact under biaxial stretching

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

Adhesive contact of the Hertzian indenter with an incompressible elastic substrate bi-directionally stretched along the indenter principal planes of curvature is considered in the Johnson–Kendall–Roberts theoretical framework. An approximate model is constructed by examining energy release rate conditions only on the edges of the minor and major axes of the contact ellipse. The effect of weak coupling between fracture modes I and II is introduced using a phenomenological mode-mixity function.

On stickiness of multiscale randomly rough surfaces

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;
A new stickiness criterion for solids having random fractal roughness is derived using Persson's theory with DMT-type adhesion. As expected, we find stickiness, i.e., the possibility to sustain macroscopic tensile pressures or else non-zero contact area without load, is not affected by the truncation of the PSD spectrum of roughness at short wavelengths and can persist up to roughness amplitudes orders of magnitude larger than the range of attractive forces.

Axisymmetric JKR-type adhesive contact under equibiaxial stretching

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;
 Our research has just been published in Journal of Adhesion. It deals with axisymmetric frictionless adhesive contact problem for a spherical indenter pressed against an isotropic elastic incompressible half-space under equibiaxial stretching is studied in the framework of the generalized Johnson{Kendall{Roberts (JKR) theory, which accounts for the effect of weak coupling between fracture modes I and II by means of a phenomenological mode-mixity function. The model predicts that contact area can withstand a larger level of the substrate stretch under moderate pre-pulling force.

Shear-induced contact area anisotropy explained by a fracture mechanics model

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

A. Papangelo, J. Scheibert, R. Sahli, G. Pallares, and M. Ciavarella
Phys. Rev. E 99, 053005 - https://journals.aps.org/pre/abstract/10.1103/PhysRevE.99.053005

The role of adhesion in contact mechanics

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;

Just published in Journal of the Royal Society Interface

Ciavarella M, Joe J, Papangelo A, Barber JR. 2019 The role of adhesion in contact mechanics. J. R. Soc. Interface 16: 20180738. http://dx.doi.org/10.1098/rsif.2018.0738

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