The Adhesion Society will hold its 32nd Annual Meeting in Savannah, GA February 15-18, 2009; uniting chemists, physicists, mechanists, engineers, and biologists concerned with the design and characterization of materials interfaces and their associated property of adhesion.  Adhesion and interfacial constrol are key to the development of nano- and bio- based technologies as well structural and cosmetic applications that influence society in everyday life. 

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

Please note that a post-doc position on stresses and adhesion in optical multilayers is open. The position is for 2-years shared between SVI (Paris) and Phymat (Poitiers).

Link to a virus-free MS Word description of the position:

http://www.saint-gobain-recherche.com/svi/en/image_merethif_position.html

For further details and applications (cover letter, CV, statement of research interests):

A post-doc position on multiscale simulation of cell contact and adhesion shall be available this coming Fall at UC Berkeley. We are seeking for a person who has experience and background on finite element computations, especially in cell contact/adhesion modeling and simulation or finite deformation simulations.

Anyone who is interested in the position please send an email, resume, and reference to li@ce.berkeley.edu

With the beginning of the year 2008, the iMechanica journal club moves to two topics per month.  This first topic will be highlighted here for 1-14 January, with the next topic starting on 15 January. 

There has been much recent buzz about biology and nature, and about materials and structures that are “biomimetic” or “bio-inspired”.  A key distinction here, when compared with fields like tissue engineering, is that although information is obtained from natural objects, including biological tissues, the end-applications are industrial and not necessarily biomedical.

It seems there are quite a few experimental studies [1,2] on the fracture properties of porous materials, like nanoporous low-k dielectrics, as a function of porosity. Can anyone point out some references on the theoretical part, like the available models, computational methods or analytical approaches that can capture microstructure information, including porosity, pore geometry etc. Interface delamination of porous materials is also of interest. Thanks.

Yesterday I had the distinct pleasure of seeing a mechanics seminar delivered "tag-team" by Ken Johnson and Jim Greenwood. (I know several people have thought I was a bit mad for jumping "across the pond" but there are really some amazing benefits of being part of the Cambridge Engineering faculty!)

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

As I promised, I start with some brief notes on themes loved by Ken Johnson to hopefully raise some interest for discussion on iMechanica. Regards, Mike

In this short note we remark that, at least for the theory of Fuller & Tabor for the adhesive contact of rough random surfaces, fractal surfaces have a limiting zero pull-off force, for all fractal dimensions or amplitudes of roughness. This paradoxical result raises some questions. I ask the iMechanica community for opinions, comparisons of experiments, etc.

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

Ting Y. Tsui, Andrew J. McKerrow, and Joost J. Vlassak

Published in the Journal of The Mechanics and Physics of Solids, 54 (5), 887-903 (2006)

Abstract – Organosilicate glass (OSG) is a material that is used as a dielectric in advanced integrated circuits. It has a network structure similar to that of amorphous silica where a fraction of the Si-O bonds has been replaced by organic groups. It is well known from prior work that OSG is sensitive to subcritical crack growth as water molecules in the environment are transported to the crack tip and assist in rupturing Si-O bonds at the crack tip. In this study, we demonstrate that exposure of an OSG containing film stack to water prior to fracture results in degradation of the adhesion of the film stack. This degradation is the result of the diffusion of water into the film stack. We propose a quantitative model to predict adhesion degradation as a function of exposure time by coupling the results of independent subcritical crack growth measurements with diffusion concentration profiles. The model agrees well with experimental data and provides a novel method for measuring the water diffusion coefficient in film stacks that contain OSG. This study has important implications for the reliability of advanced integrated circuits.

Zhigang Suo, Joost Vlassak, and Sigurd Wagner