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Contact mechanics of rough surfaces

English title Contact mechanics of rough surfaces
Applicant Molinari Jean-François
Number 162569
Funding scheme Project funding (Div. I-III)
Research institution Laboratoire de simulation en mécanique des solides EPFL - ENAC - IS - LSMS
Institution of higher education EPF Lausanne - EPFL
Main discipline Mechanical Engineering
Start/End 01.10.2015 - 30.09.2019
Approved amount 548'167.00
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Keywords (6)

Rate and State Friction; Contact Mechanics; Boundary Element Method; Microcontacts; Finite Element Method; Surface Roughness

Lay Summary (French)

Lead
Prof. Jean-Francois Molinari, EPFL
Lay summary

La mécanique du contact et le frottement ont une importance considérable partout où il y a du mouvement. Beaucoup de nos connaissances restent néanmoins empiriques. Ce projet a pour but d’améliorer la robustesse des théories existantes en incorporant dans la physique du contact la rugosité des surfaces.

Le frottement est tout autour de nous, dans les machines jusqu’aux tremblements de terre. La compréhension fondamentale de ce mécanisme reste limitée. Ceci peut être expliqué par la grande complexité des mécanismes physiques entrant en jeu à de nombreuses échelles de grandeur. Le rôle joué par la rugosité des surfaces bien que primordiale n’est pas encore bien compris. La rugosité dicte où se trouvent les microcontacts (c’est-à-dire aux sommets des aspérités qui se touchent) et donc les forces de frottement. Le but de ce projet est de prendre en compte explicitement les interactions entre aspérités afin d’obtenir une base théorique physique de la mécanique du contact. Le but ultime est d’expliquer l’origine de certains paramètres empiriques des lois de frottement « rate and state ». L’outil d’investigation est la simulation numérique à haute performance.

Des simulations numériques sont conduites avec des surfaces rugueuses statistiquement représentatives, c’est-à-dire avec de nombreuses aspérités. L’objectif est d’établir un lien entre la rugosité, soit la géométrie, les chargements, et le développement de la surface réelle de contact qui est constituée de nombreux micro contacts. Nous suivrons l’évolution de ces microcontacts en fonction du glissement afin d’enrichir la physique des modèles phénoménologues de frottement.

Cette recherche se propose d’expliquer l’origine de paramètres purement phénoménologiques des lois de frottement utilisées en ingénierie et en géophysique pour modéliser les tremblements de terre. Cette recherche fondamentale permettra de mieux comprendre le lien entre les interactions microscopiques (contact aux aspérités) et les instabilités de glissement macroscopiques.

Direct link to Lay Summary Last update: 07.12.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
A Fourier-Accelerated Volume Integral Method for Elastoplastic Contact
Frérot Lucas, Bonnet Marc, Molinari Jean-Francois, Anciaux Guillaume (2019), A Fourier-Accelerated Volume Integral Method for Elastoplastic Contact, in Computer Methods in Applied Mechanics and Engineering, 351, 951-976.
Unstable Slip Pulses and Earthquake Nucleation as a Non-Equilibrium First-Order Phase Transition
Brener E.A., Aldam M., Barras F., Molinari J. F., Bouchbinder E. (2018), Unstable Slip Pulses and Earthquake Nucleation as a Non-Equilibrium First-Order Phase Transition, in Physical Review Letters, 121(23), 234302.
Supershear Bursts in the Propagation of a Tensile Crack in Linear Elastic Material
Barras Fabian, Carpaij René, Geubelle Philippe H., Molinari Jean-Franç cois (2018), Supershear Bursts in the Propagation of a Tensile Crack in Linear Elastic Material, in Physical Review E, 98(6), 063002-063002.
A Mechanistic Understanding of the Wear Coefficient: From Single to Multiple Asperities Contact
Frérot Lucas, Aghababaei Ramin, Molinari Jean-Francois (2018), A Mechanistic Understanding of the Wear Coefficient: From Single to Multiple Asperities Contact, in Journal of the Mechanics and Physics of Solids, 114, 172-184.
Interplay between Process Zone and Material Heterogeneities for Dynamic Cracks
Barras Fabian, Geubelle Philippe H., Molinari Jean-Francois (2017), Interplay between Process Zone and Material Heterogeneities for Dynamic Cracks, in Physical Review Letters, 119(14), 144101-144101.
The Emergence of Crack-like Behavior of Frictional Rupture: The Origin of Stress Drops
Barras Fabian, Aldam Michael, Roch Thibault, Brener Efim A., Bouchbinder Eran, Molinari Jean-Francois, The Emergence of Crack-like Behavior of Frictional Rupture: The Origin of Stress Drops, in Physical Review X.

Datasets

The Mindlin Fundamental Solution - A Fourier Approach

Author Frérot, Lucas
Publication date 20.11.2018
Persistent Identifier (PID) 10.5281/zenodo.1492149
Repository zenodo
Abstract
This notebook describes the process of derivation of the (Mindlin, 1936) fundamental solution in a hybrid Fourier/physical space, convenient for the half-space nature of the solution and numerical application of the Mindlin tensor via a Fast-Fourier Transform (FFT).

Collaboration

Group / person Country
Types of collaboration
Dr. Jeremy Bleyer, ENPC France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Marc Bonnet, ENSTA France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Philippe Geubelle, University of Illinois at Urbana Champain United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Daniel Bonamy, CEA France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Eran Bouchbinder group, Weizmann Institute Israel (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
ASML Individual talk Tribology across scales (invited seminar) 06.11.2019 Veldhoven, Netherlands Molinari Jean-François;
GDR Workshop on Computational Tribology Talk given at a conference Tribology from the nano to the mesoscale (invited keynote) 10.10.2019 Bordeaux, France Molinari Jean-François;
10th anniversary Novelis R&D center Talk given at a conference Tribology across scales (invited keynote) 06.09.2019 Sierre, Switzerland Molinari Jean-François;
CECAM workshop: Interface dynamics and dissipation across time and length scales Talk given at a conference Is friction fracture? When, where and how? (invited keynote) 20.05.2019 Tel Aviv, Israel Molinari Jean-François;
Mach conference Talk given at a conference The origin of stress drops in frictional rupture (invited talk) 03.04.2019 Annapolis, United States of America Molinari Jean-François;
Earthflows workshop Talk given at a conference Emergence of self-affine roughness during adhesive wear (invited keynote) 19.01.2019 Oslo, Norway Molinari Jean-François;
International Joint Workshop on Slow Earthquakes 2018 Talk given at a conference Emergence of self-affine roughness during dry sliding: insights from atomistic simulations (invited keynote) 21.09.2018 Fukuoka, Japan Molinari Jean-François;
41st Solid Mechanics Conference Talk given at a conference Origins of adhesive wear (plenary talk) 27.08.2018 Warsaw, Poland Molinari Jean-François;
13th World Congress in Computational Mechanics (WCCM XIII) Talk given at a conference Shock Waves produced by the interaction of dynamic crack with heterogeneities 22.07.2018 New York, United States of America Barras Fabian;
10th European Solid Mechanics Conference Talk given at a conference Evolution of roughness during dry sliding: insights from atomistic and mesoscale models (invited keynote) 02.07.2018 Bologna, Italy Molinari Jean-François;
6th European Conference on Computational Mechanics Talk given at a conference An FFT-Based Numerical Method for Elasto-Plastic Contact 11.06.2018 Glagow, Great Britain and Northern Ireland Frérot Lucas;
Contact Mechanics International Symposium Talk given at a conference Friction and wear across scales (invited keynote) 16.05.2018 Sanctuary of Oropa, Biella, Italy Molinari Jean-François;
Condensed Matter Physics seminar, The Johns Hopkins University Individual talk Friction and wear across scales (invited seminar) 11.04.2018 Baltimore, United States of America Molinari Jean-François;
Mach Conference Talk given at a conference Dynamic crack propagation in heterogeneous materials (plenary talk) 04.04.2018 Annapolis, United States of America Molinari Jean-François;
16th European Mechanics of Materials Conference Talk given at a conference Origins of adhesive wear 26.03.2018 Nantes, France Molinari Jean-François;
Mechanical instabilities in solids and fluids workshop Talk given at a conference Wear across scales (invited keynote) 16.10.2017 Hebrew University, Jerusalem, Israel Molinari Jean-François;
ECCOMAS Young Investigators Conference 2017 Talk given at a conference Wear Coefficient and Contact Cluster Statistics 13.09.2017 Milano, Italy Frérot Lucas;
5th International Conference on Computational Modeling of Fracture and Failure of Materials and Structures (CFRAC) Talk given at a conference On the dynamic perturbation of crack front by micro-scale material heterogeneities 14.06.2017 Nantes, France Barras Fabian;
Aarhus University, Aarhus, invited seminar Individual talk Mechanics of Surface Damage: A new look at the old problem of wear 14.06.2017 Aarhus, Denmark Aghbabaei Ramin;
6th European Conference on Computational Mechanics Talk given at a conference Continuum versus Discrete Approach in Modeling of Wear Processes 11.06.2017 Glasgow, Great Britain and Northern Ireland Frérot Lucas;
Micro/nanoscale Models for Tribology (micro/n-tribo-models) Talk given at a conference Three centuries of research on wear 30.01.2017 Leiden, Netherlands Aghbabaei Ramin;
Karlsruhe Institute of Technology, invited seminar Individual talk Spanning Length Scales in Plasticity- and Fracture-Induced Surface Damage in Metals and Ceramics 09.09.2016 Karlsruhe, Germany Aghbabaei Ramin;
European Conference on Fracture (ECF 21) Talk given at a conference The dynamic rupture of interfaces made of heterogeneous fracture properties 20.06.2016 Catania, Italy Barras Fabian;
Society of Engineering Science, 52nd Annual Technical Meeting Talk given at a conference The role of elastic waves during dynamic rupture of heterogeneous interfaces 26.10.2015 College station, Texas, United States of America Barras Fabian;


Self-organised

Title Date Place
CECAM workshop in Lausanne, Modeling tribology: friction and fracture across scales 28.01.2019 Lausanne, Switzerland

Awards

Title Year
EPFL Outstanding PhD Thesis Distinction in Civil and Environmental Engineering for the year 2018 2019

Associated projects

Number Title Start Funding scheme
191720 Tribology of Polymers: from Atomistic to Continuum Scales 01.02.2020 Early Postdoc.Mobility

Abstract

Friction is all around us. It is present in virtually all engineering applications, and we experience it at the large scale during earthquakes. Perhaps surprisingly, our fundamental comprehension of friction mechanisms remains quite limited. Science has made significant progress at understanding some of the molecular mechanisms resulting in energy dissipation and friction at contacting asperities. However, the disconnection between the atomic and the macroscopic scales results in engineering models that are often based on mere fit parameters. An example is provided by rate-and-state friction laws, which describe the non-instantaneous response of the friction coefficient due to sudden changes of the sliding velocity or the contact pressure. These models rely on characteristic time-scale or length-scale parameters, the latter being loosely and empirically associated to the size of micro contacts, which develop when rough surfaces are pressed upon one another. In order to improve our current engineering description of friction and to predict or tune the frictional behavior of surfaces, models linking microscopic characteristics of rough surfaces to their engineering-scale properties are in dire need.Using the strengths of the PIs in mechanics of solids and numerical modeling, the key objective of this research is to bridge the gap between microscopic and engineering scales by focusing on the often overlooked scale at which contacting asperities interact and adapt to their environment. We call it the mesoscale. Within an efficient continuum mechanics framework in conjunction to high-performance computing resources, we will be in position to track the time evolution of statistically significant rough surfaces under normal loading in the presence of visco-plastic deformation, at the onset of sliding and during sliding contact. The research will yield direct insights on the contributing factors (including geometry, boundary conditions, and material parameters) to a macroscopic friction coefficient and the characteristic time and length scales used in rate-and-state friction models. This is a crucial step for constructing predictive friction models.
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