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