Static Fatigue Controls Particle Crushing and Time Effects in Granular Materials

Static friction phenomena in granular materials: Coulomb law versus particle geometry.

The static as well as the dynamic behaviour of granular material are determined by dynamic and static friction. There are well known methods to include static friction in molecular dynamics simulations using scarcely understood forces. We propose an Ansatz based on the geometrical shape of nonspherical particles which does not involve an explicit expression for static friction. It is shown that...

Lecture 3 : Time Effects Observed in Granular Materials

Virtually every soil "lives" in that all of its properties undergo changes with time some insignificant, but others very important. Time-dependent chemical, geomicrobiological, and mechanical processes may result in compositional and structural changes that lead to softening, stiffening, strength loss, strength gain, or altered conductivity properties. The need to predict what the properties an...

Memory effects in granular materials

We present a combined experimental and theoretical study of memory effects in vibration-induced compaction of granular materials. In particular, the response of the system to an abrupt change in shaking intensity is measured. At short times after the perturbation a granular analog of aging in glasses is observed. Using a simple two-state model, we are able to explain this short-time response. W...

Characterization of static and dynamic structures in granular materials

Jamming and static stress transmission in granular materials.

We have recently developed some simple continuum models of static granular media which display "fragile" behavior: They predict that the medium is unable to support certain types of infinitesimal load (which we call "incompatible" loads) without plastic rearrangement. We argue that a fragile description may be appropriate when the mechanical integrity of the medium arises adaptively, in respons...