Njord Seminar with Jay Fineberg
Jay Fineberg (The Hebrew University of Jerusalem): How Friction Starts: Nucleation fronts initiate frictional motion
Rapid rupture fronts, akin to earthquakes, mediate the transition to frictional motion. Once formed, their singular form, dynamics and arrest are well-described by fracture mechanics. Ruptures, however, first need to be created within initially rough frictional interfaces. Hence, ``static friction coefficients” are not well-defined; frictional ruptures nucleate over a wide range of applied forces. A critical open question is, therefore, how the nucleation of rupture fronts actually takes place. Here, we experimentally show that rupture fronts are prefaced by slow nucleation fronts; self-similar entities not described by fracture mechanics. They emerge from initially rough frictional interfaces at a well-defined stress threshold, evolve at characteristic velocity and time scales governed by stress levels, and propagate within a frictional interface to form the initial rupture from which fracture mechanics take over. These results are of fundamental importance to questions ranging from earthquake nucleation and prediction to processes governing material failure.
You will find the complete schedule for Njord Seminar Series spring '21 here.
To get news, invitations to seminars and more from Njord, please go here to subscribe to our newsletter.