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Concept

Asperity (materials science)

Publications associées (23)

Roughness Evolution Induced by Third-Body Wear

Jean-François Molinari, Tobias Brink, Antonio Joaquin Garcia Suarez

Surface roughness is a key factor when it comes to friction and wear, as well as to other physical properties. These phenomena are controlled by mechanisms acting at small scales, in which the topography of apparently flat surfaces is revealed. Roughness i ...

2024

A story of two transitions: From adhesive to abrasive wear and from ductile to brittle regime

Jean-François Molinari, Sacha Zenon Wattel

Atomistic simulations performed with a family of model potential with tunable hardness have proven to be a great tool for advancing the understanding of wear processes at the asperity level. They have been instrumental in finding a critical length scale, w ...

2024

Modeling the origins of adhesive wear across scales

Son-Jonathan Pham-Ba

Friction and wear occur at every interface between solid materials. In the design of mechanical devices, it is desirable to be able to quantify and control the amount of friction and wear, as well as predict their evolution with time. ``Tribology'' is the ...

EPFL2022

Understanding the mechanisms of adhesive wear for heterogeneous materials through atomistic simulations

Jean-François Molinari, Antonio Joaquin Garcia Suarez, Sacha Zenon Wattel

When two rough surfaces slide against each other, two main behaviors can be observed at the asperity level: A ductile behavior where the asperities tend to smooth out or a brittle behavior where the asperities detach and form debris. Recently, a critical l ...

2022

Determination of Parameters Characteristic of Dynamic Weakening Mechanisms During Seismic Faulting in Cohesive Rocks

Marie Estelle Solange Violay, François Xavier Thibault Passelègue, Chiara Cornelio

While sliding at seismic slip-rates of ∼1 m/s, natural faults undergo an abrupt decrease of shear stress called dynamic weakening. Asperity-scale processes related to flash heating and weakening and, meso-scale (mm-cm) processes involving shear across the ...

AGU2022

A numerical study of the statistics of roughness parameters for fluctuating interfaces

Elisabeth Agoritsas

Self-affine rough interfaces are ubiquitous in experimental systems, and display characteristic scaling properties as a signature of the nature of disorder in their supporting medium, i.e. of the statistical features of its heterogeneities. Different metho ...

2021

Onset of sliding across scales: How the contact topography impacts frictional strength

Jean-François Molinari, Ramin Aghababaei, Fabian Barras

When two solids start rubbing together, frictional sliding initiates in the wake of slip fronts propagating along their surfaces in contact. This macroscopic rupture dynamics can be successfully mapped on the elastodynamics of a moving shear crack. However ...

AMER PHYSICAL SOC2021

Adhesive wear regimes on rough surfaces and interaction of micro-contacts

Jean-François Molinari, Son-Jonathan Pham-Ba

We develop an analytical model of adhesive wear between two unlubricated rough surfaces, forming micro-contacts under normal load. The model is based on an energy balance and a crack initiation criteria. We apply the model to the problem of self-affine rou ...

2021

Nonlocal Effects Reflect the Jamming Criticality in Frictionless Granular Flows Down Inclines

Matthieu Wyart, Hugo Robin Louis Perrin

The jamming transition is accompanied by a rich phenomenology such as hysteresis or nonlocal effects that is still not well understood. Here, we experimentally investigate a model frictionless granular layer flowing down an inclined plane as a way to disen ...

AMER PHYSICAL SOC2021

The emergence of small-scale self-affine surface roughness from deformation

Till Junge

Most natural and man-made surfaces appear to be rough on many length scales. There is presently no unifying theory of the origin of roughness or the self-affine nature of surface topography. One likely contributor to the formation of roughness is deformati ...

AMER ASSOC ADVANCEMENT SCIENCE2020

Bridging scales in wear modeling with volume integral methods for elastic-plastic contact

Lucas Henri Galilée Frérot

All mechanical systems, naturally occurring or human-produced, are subjected to friction and wear at the interface of solid constituents. Large portions of energy dissipation and loss of material, in every-day life and industrial applications alike, are du ...

EPFL2020

Crack Nucleation in the Adhesive Wear of an Elastic-Plastic Half-Space

Jean-François Molinari, Guillaume Anciaux, Lucas Henri Galilée Frérot

The detachment of material in an adhesive wear process is driven by a fracture mechanism which is controlled by a critical length-scale. Previous efforts in multi-asperity wear modeling have applied this microscopic process to rough elastic contact. Howeve ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Emergence of self-affine surfaces during adhesive wear

Jean-François Molinari, Ramin Aghababaei, Tobias Brink, Enrico Milanese

Friction and wear depend critically on surface roughness and its evolution with time. An accurate control of roughness is essential to the performance and durability of virtually all engineering applications. At geological scales, roughness along tectonic ...

Nature Research2019

A mechanistic understanding of the wear coefficient: From single to multiple asperities contact

Jean-François Molinari, Ramin Aghababaei, Lucas Henri Galilée Frérot

Sliding contact between solids leads to material detaching from their surfaces in the form of debris particles, a process known as wear. According to the well-known Archard wear model, the wear volume (i.e. the volume of detached particles) is proportional ...

2018

Asperity-Level Origins of Transition from Mild to Severe Wear

Jean-François Molinari, Ramin Aghababaei, Tobias Brink

Wear is the inevitable damage process of surfaces during sliding contact. According to the well-known Archard’s wear law, the wear volume scales with the real contact area and as a result is proportional to the load. Decades of wear experiments, however, s ...

2018

Normal adhesive contact on rough surfaces: efficient algorithm for FFT-based BEM resolution

Jean-François Molinari, Guillaume Anciaux, Valentine Ginette Madeleine Rey

We introduce a numerical methodology to compute the solution of an adhesive normal contact problem on rough surfaces with the Boundary Element Method. Based on the Fast Fourier Transform and the Westergaard’s fundamental solution, the proposed algorithm en ...

2017

The role of the roughness spectral breadth in elastic contact of rough surfaces

Jean-François Molinari, Guillaume Anciaux, Vladislav Yastrebov

We study frictionless and non-adhesive contact between elastic half-spaces with self-affine surfaces. Using a recently suggested corrective technique, we ensure an unprecedented accuracy in computation of the true contact area evolution under increasing pr ...

2017

Critical length scale controls adhesive wear mechanisms

Jean-François Molinari, Ramin Aghababaei

The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to w ...

Springer2016

Tribocorrosion under fluid lubrication : modeling wear of CoCrMo artificial hip joints

Shoufan Cao

Wear is still the key problem causing the failure and limiting the lifetime of artificial hip joints, especially for the polymer acetabular cup in the metal-on-polymer and ceramic-on-polymer articulations. To reduce the wear, metal-on-metal articulation ha ...

EPFL2016

Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

Marie Estelle Solange Violay

Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening) with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s(2)), slip rates (similar to 1 ...

Mdpi Ag2016