Publications associées à Graisse (mécanique)

Influence of Viscous Lubricant on Nucleation and Propagation of Frictional Ruptures

Marie Estelle Solange Violay, François Xavier Thibault Passelègue, Federica Paglialunga

Fluids are pervasive in the Earth's crust and saturate fractures and faults. The combination of fluids and gouge layers developing along faults can generate fluids of different viscosities. Such viscous fluids were found to influence the reactivation, fric ...

2023

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

A Simple Mechanistic Model for Friction of Rough Partially Lubricated Surfaces

Jean-François Molinari, Tobias Brink, Gianluca Costagliola, Julie Richard

We report experimental measurements of friction between an aluminum alloy sliding over steel with various lubricant densities. Using the topography scans of the surfaces as input, we calculate the real contact area using the boundary element method and the ...

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

The Role of Geometrical Parameters in the Lubrication of the Swiss Lever Escapement

Stefano Mischler, Alejandro Roda Buch, Sandra Guadalupe Maldonado

The lubrication regimes of a contact pair escapement-ruby pallet of a Swiss lever escapement have been investigated combining the theory of fluid lubrication with a well-established kinematic and inverse dynamic multibody model. The kinematic analytical re ...

2021

Optimization of a Py-GC/MS method for silicone -based lubricants analysis

Christophe Roussel, Céline Burnier

Condom evidence can be analysed using several analytical techniques, such as FTIR, MALDI-MS or DART-TOF-MS, but the only one that was used on real samples for transfer and persistence studies in the context of sexual assault or rape cases was Py-GC/MS. How ...

2020

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

Tribocorrosion of a CoCrMo alloy in sulfuric acid - Glycerol mixtures

Stefano Mischler, Shoufan Cao

This work reports on the tribocorrosion properties of a CoCrMo alloy sliding under imposed passive potential against alumina in sulfuric acid-glycerol mixtures exhibiting different viscosities and thus, in principle, lubrication properties. As expected, we ...

ELSEVIER SCIENCE SA2020

Film thickness distribution in gravity-driven pancake-shaped droplets rising in a Hele-Shaw cell

François Gallaire, Gioele Mariano Nicolò Balestra, Nicolas Igor Jacques Kofman, Lailai Zhu, Isha Shukla

We study here experimentally, numerically and using a lubrication approach, the shape, velocity and lubrication film thickness distribution of a droplet rising in a vertical Hele-Shaw cell. The droplet is surrounded by a stationary immiscible fluid and mov ...

Cambridge University Press2019

Thin Gas Film Isothermal Condensation in Aerodynamic Bearings

Jürg Alexander Schiffmann, Eliott Philippe Guenat

High-speed small-scale turbomachinery for waste heat recovery and vapor compression cycles is typically supported on gas-lubricated bearings operating close to the saturation conditions of the lubricant. Under particular conditions, the gas film might loca ...

2019

Miniaturized tube fixed plug drawing: determination of the friction coefficients and drawing limit of 316 LVM stainless steel

Jean-Marie Drezet, Stefano Mischler, Nicolas Paul Henry Chobaut, Bastien De Marco, Vance Nguyen, Stéphane Dobler

Tube drawing with a ﬁxed plug is investigated experimentally and numerically in order to optimise an industrial pass sequence. Tube drawings are performed on a laboratory drawing bench equipped with force, displacement and temperature sensors. The drawing ...

2018

Viscous growth and rebound of a bubble near a rigid surface

François Gallaire, Giacomo Gallino

Motivated by the dynamics of microbubbles near catalytic surfaces in bubble-powered microrockets, we consider theoretically the growth of a free spherical bubble near a flat no-slip surface in a Stokes flow. The flow at the bubble surface is characterised ...

Cambridge University Press2018

The dam-break problem for eroding viscoplastic fluids

Christophe Ancey, Belinda Margaret Bates

Natural gravity-driven flows can increase in volume by eroding the bed on which they descend. This process is called basal entrainment and is thought to play a key role in the bulk dynamics of geophysical flows. Although its study is difficult using field ...

Elsevier2017

Effect of surface films on tribologically induced metallurgical transformations of steel in oil lubricated contacts

Stefano Mischler, Marco Cantoni, Shoufan Cao

This study was initiated with the aim to assess the influence of boundary films on the tribologically induced metallurgical transformations and deformations of metals in lubricated contacts and their effect on wear. For this, the tribological behavior of a ...

Elsevier Science Sa2016

Tribology of surface-grafted polymer brushes

Harm-Anton Klok, Piotr Mocny

Surface-grafted polymer brushes are a very attractive class of boundary lubricants. This article presents an overview of the tribological properties of surface-attached synthetic polymers. After a brief review of some mechanistic considerations and a discu ...

Royal Soc Chemistry2016

Characterization of Grey Cast Iron-Steel Tribo-system under Starved Lubrication Conditions : Failure, Failure Detection and Laser Surface Texturing

Fatemeh Saeidi

Reducing friction and wear is essential for building efficient systems with low energy consumption and a long lifetime. Surface texturing is one of the methods to reduce friction and wear, especially in oil-lubricated systems. However, there is still a lac ...

EPFL2016

A Simple, Fast and Low-Cost Method for in situ Monitoring of Topographical Changes and Wear Rate of a Complex Tribo-System Under Mixed Lubrication

Daniel Sage, Bastian Meylan

This contribution presents a simple, fast, and low-cost method to track in situ and in real time the evolution of the surface topography. The method combines an optical method (collimated light) with image analysis. The method was validated using a complex ...

Elsevier2016

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

Underwater propelling device for underwater vehicle

Alexander Bahr, Felix Stephan Schill

The present invention relates to an underwater propelling device (10) i a stator (20) comprising circumferential arrayed coils (35) and being adapted to generate a controlled electromagnetic field along an axial direction, a shaftless propellant rotor (30) ...

2016

Dry wear and tribocorrosion mechanisms of pulsed plasma nitrided Ni-Cr alloy

Stefano Mischler

The dry wear and tribocorrosion behaviour of pulsed plasma treated and non-treated Ni-Cr alloys sliding against alumina at 15 N were investigated by using a reciprocating wear test rig equipped with an electrochemical cell. The pulsed plasma treatment prod ...

2011