The dynamics of the onset of frictional slip: friction or fracture?

Speaker:Professor Jay Fineberg
Affiliation:The Racah Institute of Physics, Hebrew University of Jerusalem
Location:Lidow Rosen Auditorium (323)

The dynamics of how two rough frictional interfaces detach is a fundamental question in fields ranging from material science to geophysics. On the one hand, the onset of frictional motion is thought to be characterized by the static friction coefficient that couples two materials. For hundreds of years, this has been considered to be a material constant. On the other hand, the same processes that give rise to the onset of frictional motion also cause earthquakes, when tectonic plates locked together by friction start to slip. We describe new experiments that examine how rapid crack-like processes that fracture a frictional interface cause the onset of macroscopic motion that we know as frictional sliding. Results of this study are surprising. We both demonstrate that a number of different types of earthquakes exist and that the “static friction coefficient” is not a material constant at all, but is intimately related to the details of how forces are applied to a system.