Logjams and Haystacks: Jamming in Rod-like Granular Materials
Scott Franklin
Department of Physics, Rochester Institute of Technology
Abstract
Why can you run your hands through rice but not nails? The physics of
large aspect-ratio (L/D>>10) granular materials is a relatively
unexplored area of research with important industrial consequences.
Such materials form connected networks significantly more rigid than
those found in ordinary (round) granular materials, a feature
well-known to anyone who has used a pitchfork to move hay. I will
describe recent experiments that investigate these networks in both
two- and three-dimensions, with an emphasis on the transition to a
jammed state in which the pile acts as a solid body. This solid body
behavior is unique to large aspect-ratio particles, depends
significantly on the container in which the particles are placed, and
forms the basis of the industrial utility of the materials.