Sunday, 1 April 16:00

Stress and Structure in Granular Materials

Sam Edwards, Cavendish Laboratory, Univeristy of Cambridge, England

Abstract

The simplest stress problem is to consider hard rough grains all in
contact. The stress resulting from external forces then can only depend on
the geometry of contacts. Counting degrees of freedom, in the complete
absence of strain, there are "missing equations" which must emerge from the
geometry. These are derived.
They depend on certain tensors from the geometry and it is then argued that
from the Chicago experiments an analogue of ergodicity obtains in granular
materials, and the analogue of temperature is dV/dS,
where V is the volume and S the entropy. It is then shown that V
depends on the same geometrical tensors arising in the stress problem and
it is hoped in this way to produce a unification of the statics of powders.