Graduate assistantship positions are available in the Computational olid Mechanics Laboratory (http://lsms.epfl.ch/) at the Ecole olytechnique Fédérale de Lausanne (http://www.epfl.ch/).
We are interested in highly motivated Ph.D. candidates with an academic background (B.S. and M.S.) in either Mechanical Engineering, Civil ngineering or Computational Materials Science.

A Post-Doc Position is avalaible in Bio-Mimetic Adhesive Interfaces (EbioAdI) at the University of Mons-Hanaut, Belgium

Recent experiments in sliding friction are a major embarassment for all present understanding of friction using Coulomb or Rice-Ruina-Dieterich-Prakash rate-state dependent theories, which are the subject of large research programs. In particular, Rubinstein et al; (Detachment fronts and the onset of dynamic friction. Nature 430, 1005—1009. 2004) suggest that the contact area is not significantly altered by the fast fronts which perhaps are only precursors to the most important "slow fronts" travelling at speeds about 1/10 of the Rayleigh speed.

Authors are invited to submit, via the conference website, a 200-250 word abstract by 1 June 2008. The 17th International Conference on Wear of Materials (www.wom-conference.elsevier.com) will take place in Las Vegas, April 19-22, 2009. The conference will focus on both the fundamental and applied aspects of wear and friction of materials at the macro-, micro- and nano-scale.

Study of wear in complex micro-mechanical components is often accomplished experimentally using a pin-
on-disc and twin-disc tribometer. The present paper proposes an approach that involves a computationally
efficient incremental implementation of Archard’s wear model on the global scale for modeling sliding and
slipping wear in such experiments. It will be shown that this fast simplistic numerical tool can be used to
identify the wear coefficient from pin-on-disc experimental data and also predict the wear depths within a
limited range of parameter variation. Further it will also be used to study the effect of introducing friction

B. Li, M. K. Kang, K. Lu, R. Huang, P. S. Ho, R. A. Allen, and M. W. Cresswell, Nano Letters 8, 92 -98 (2008). (Web Release Date: 07-Dec-2007; DOI: 10.1021/nl072144i)

A systematic characterization of the motion and friction of a linear bearing with rolling elements used for nanopositioning reveals an explicit distinction of static and rolling friction. The effects

We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C60 and C20) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of  5.283×10-7 nN/atom and  6.768×10-7 nN/atom  for C60 and C20 bearings) and energy dissipation (lowest dissipation per cycle of  0.013 meV/atom  and  0.016 meV/atom  for C60 and C20 bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings.

Based on some recent results by Anders Klabring, myself and Jim Barber, showing rigorously that Melan’s theorem only works for a very restricted class of frictional problems, we suggest possible ave

If we read Ken Johnson’s Timoshenko medal 2006 speech also posted in iMechanica, the subjects Ken mentions in his brief and humorous speech are:-

1. corrugation of railway rails,
2. the damping at clamped joints,
3. Hertz contact under the action of tangential friction forces,
4. ‘tribology' (word invented by David Tabor along with F.P.Bowden in Cambridge),
5. Atomic Force Microscope, Surface Force Apparatus & friction on the atomic scale,
6. Relation between adhesion and friction.

These are probably the subjects Ken is most attached to. Some are older (but perhaps not solved, lke corrugation, for which the “short-pitch” fixed wavelength mechanism is still unclear despite Ken’s 40 years of efforts (!), and some are certainly fashionable today (like adhesion and friction at atomic scale). In starting this forum, why not start from here? Should we prepare a 1 page summary on each of these topics? Since I start this, I will do the effort on corrugation I promise in the next week or so!

Regards, Mike

Anders Klarbring, Jim Barber and I are preparing a paper on the subject of shakedown in elastic contact problems with Coulomb friction. In particular, we establish the (rather limited) conditions under which a frictional equivalent of Melan's theorem can be applied, and we counterprove the theorem in all other cases.There is no plasticity here - the contacting bodies are linear elastic - but the analogies between the Coulomb friction law and elastic plastic deformation make us think the plasticity community might be interested in the results.

Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the high precision positioing stages. We published a paper recently in Technishes Messen (TM) on a study of the friction behavior in the moving range of micrometers. It provides info for the development of friction models targeted for the motion control in high precision engineering.

The following is the abstract, and the full paper can be downloaded from http://www.atypon-link.com/OLD/doi/abs/10.1524/teme.2006.73.9.500

ABSTRACT Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the nanopositioning and nanomeasuring machine (NPM) system. We present the frictional behaviour of some selected materials, coatings, lubricants, and bearings tested under running conditions similar to a NPM system. Continuous change of surface properties results in various friction characteristics, which substantiate the further development of tribological coatings, particularly for vacuum applications. We emphasize the system engineering approach in developing friction models, which combines fundamental knowledge of surface science, materials science, and its applications in design, construction and automatic control.