The dragging velocity of a model solid lubricant (a 1D harmonic chain) confined between sliding periodic substrates [1] exhibits a phase transition between two regimes, respectively with fixed and with continuous lubricant relative velocities. The transition, which takes place for increasing forcing velocity or for increasing lubricant stiffness, displays a large hysteresis, and shares features of depinning transitions in static friction, only taking place on the fly.
Although different in nature, this phenomenon is approximately isomorphic to a static Aubry depinning transition of a Frenkel Kontorova model, the role of particles now taken by the moving solitons of the lubricant-substrate interface.
[1] A. Vanossi, N. Manini, G. Divitini, G.E. Santoro, and E. Tosatti, Phys. Rev. Lett. 97, 056101 (2006). |