Mardi 3 mars 2026 à 11h00, amphi F. Canac, LMA
Abstract : Tribology studies how surfaces interact through contact, friction, and wear, often revealing unexpected physical mechanisms in seemingly simple systems. In this seminar, I will present two recent research directions exploring interfacial mechanics across soft and brittle materials.
In the first part, I will discuss viscous adhesion between soft surfaces separated by a thin liquid film, inspired by biological attachment systems. When compliant substrates are involved, viscous suction couples with elasticity and generates an effective adhesion reminiscent of JKR-like contact mechanics, despite the absence of direct solid contact. Detachment proceeds through a fracture-like propagation of the contact edge, with unusual stress singularities at the crack tip.
In the second part, I will present our work on the mechanics of pencil drawing. Beyond its artistic relevance, pencil drawing provides a simple and accessible model system to investigate frictional wear of brittle materials on rough fibrous substrates. At the microscopic scale, graphite is transferred through repeated fracture and removal of small flakes by cellulose fibers, producing heterogeneous deposition patterns. Using an automated drawing device, we systematically study how applied load, sliding speed, paper texture, and lead composition control wear rate, debris morphology, and the optical intensity of the trace.