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Center for Nonlinear Studies |
This talk is an overview of our effort to understand granular flow rheology and the influence of microscopic, grain-scale processes on dynamic friction from basic physical principles. First, I will provide a short introduction to the Shear-Transformation-Zone (STZ) theory of plastic deformation and the underlying theoretical framework of nonequilibrium thermodynamics. I will then propose a way to incorporate acoustic effects, particle angularity, and interparticle friction into the STZ model. We show good agreement with laboratory experiments on angular sand particles that indicate shear-induced acoustic compaction at intermediate strain rates. We show in addition that friction between particles is essential in producing stick-slip instabilities, which can be controlled by the confining pressure and external vibrations. These results have important implications on a variety of granular phenomena including rupture and slip along earthquake faults, and the remote triggering of instabilities.
Host: Robert Ecke and Paul Johnson