Publications associées à Stability analysis of rough surfaces in adhesive normal contact

Critical degeneracy in a nonlinear hyperbolic equation can produce atypical instability

This paper deals with the initial value problem for a semilinear wave equation on a bounded domain and solutions are required to vanish on the boundary of this domain. The essential feature of the situation considered here is that the ellipticity of the sp ...

2024

Liquid film instability of an internally coated horizontal tube

François Gallaire, Edouard Boujo, Yves-Marie François Ducimetière, Shahab Eghbali

We study numerically and theoretically the gravity-driven flow of a viscous liquid film coating the inner side of a horizontal cylindrical tube and surrounding a shear-free dynamically inert gaseous core. The liquid-gas interface is prone to the Rayleigh-P ...

AMER PHYSICAL SOC2023

On the relationship between the multi-region relaxed variational principle and resistive inner-layer theory

Joaquim Loizu Cisquella, Ankit Kumar

We show that the variational energy principle of the multi-region relaxed magnetohydrodynamic (MRxMHD) model can be used to predict finite-pressure linear tearing instabilities. In this model, the plasma volume is sliced into sub-volumes separated by 'idea ...

2023

The General Crack Component Model for reversed cyclic shear

David Michael Volpe Ruggiero

A growing body of research has shown that reversed cyclic shear loading of reinforced concrete (RC) causes effects that are not accounted for in monotonic behavioral models. Notable among these effects are a reduction in shear strength and significant plas ...

2023

Singular quadratic eigenvalue problems: linearization and weak condition numbers

Daniel Kressner, Ivana Sain Glibic

The numerical solution of singular eigenvalue problems is complicated by the fact that small perturbations of the coefficients may have an arbitrarily bad effect on eigenvalue accuracy. However, it has been known for a long time that such perturbations are ...

SPRINGER2023

Effect of wear particles and roughness on nanoscale friction

Jean-François Molinari, Enrico Milanese, Tobias Brink

Frictional contacts lead to the formation of a surface layer called the third body, consisting of wear particles and structures resulting from their agglomerates. Its behavior and properties at the nanoscale control the macroscopic tribological performance ...

2022

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

Exploring the inner workings of the clove hitch knot

Paul Grandgeorge, Pedro Miguel Nunes Pereira de Almeida Reis, Paul Johanns, Tomohiko Sano, Changyeob Baek

We perform a combined experimental and computational investigation of the clove hitch knot. We develop a physical model for the clove hitch by tying an elastic rod onto a rigid cylinder. In the experiments, we characterize the mechanical performance, geome ...

ELSEVIER2022

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

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

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

Adhesive wear with a coarse-grained discrete element model

Jean-François Molinari, Son-Jonathan Pham-Ba

The use of molecular dynamics (MD) simulations has led to promising results to unravel the atomistic origins of adhesive wear, and in particular for the onset of wear at nanoscale surface asperities. However, MD simulations come with a high computational c ...

ELSEVIER SCIENCE SA2022

Second-order adjoint-based sensitivity for hydrodynamic stability and control

Edouard Boujo

Adjoint-based sensitivity analysis is routinely used today to assess efficiently the effect of open-loop control on the linear stability properties of unstable flows. Sensitivity maps identify regions where small-amplitude control is the most effective, i. ...

Cambridge University Press2021

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

Nonlinear Transient Stability Analysis of Phased-Locked Loop Based Grid-Following Voltage Source Converters Using Lyapunov’s Direct Method

Alireza Karimi, Behrooz Bahrani

In this paper, using Lyapunov’s stability theorem, the transient stability conditions for a grid-following Voltage Source Converter (VSC) are found. These conditions take into account both the grid specifications and the VSC’s dynamics. The derived conditi ...

2021

A lubricated tribocorrosion model incorporating surface roughness

Stefano Mischler, Shoufan Cao

This study presents an improvement of an existing tribocorrosion model developed for passive CoCrMo alloys. This model is based on an empirical formalism established by Duncan Dowson in his pioneering works on the relation between wear and elasto-hydrodyna ...

2021

Multi-scale modeling of aggregate interlock phenomena in concrete

Mohit Pundir

In concrete structures, opened cracks contribute significantly to the transfer of shear and normal stresses through the contact forces occurring between fractured surfaces. Such contact forces are due to protruding asperities, engaged by interlocking and f ...

EPFL2021

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

Fault Stability Across the Seismogenic Zone

François Xavier Thibault Passelègue

Across the seismogenic zone, the transition from brittle to plastic deformation corresponds to a semibrittle regime where brittle fracturing and plastic flow coexist at high strength conditions. Thorough experimental investigations on brittle-plastic trans ...

AMER GEOPHYSICAL UNION2020

Jamming with Tunable Roughness

Matthieu Wyart, Carolina Brito Carvalho dos Santos

We introduce a new model to study the effect of surface roughness on the jamming transition. By performing numerical simulations, we show that for a smooth surface, the jamming transition density and the contact number at the transition point both increase ...

AMER PHYSICAL SOC2020

Tribological Approach to the Watch Movements

Valentine Agnès Madeleine Magnin

Mechanical watches are complex and sensitive systems that have to maintain a faultless precision over their lifetime. However, this precision can be altered by disturbances occurring during the functioning time, such as friction, lubricant drying, or wear, ...

EPFL2020

Instability of a thin viscous film flowing under an inclined substrate: steady patterns

Gioele Mariano Nicolò Balestra, François Gallaire, Gaëtan Pierre Clément Lerisson, Pier Giuseppe Ledda

The flow of a thin film coating the underside of an inclined substrate is studied. We measure experimentally spatial growth rates and compare them to the linear stability analysis of a flat film modelled by the lubrication equation. When forced by a statio ...

Cambridge University Press2020