13 Pages

Model for force fluctuations in bead packs

Disordered geometric packings of granular materials [1] have fascinated researchers for many years [2]. Such studies, with their applicability to the geometry of glass-forming sys­ tems, initially were concerned with categorizing the void shapes and densities. More recently, partly in recognition of the ubiquity of granular materials and their importance to a wide variety of technological processes, interest has focused on how the forces supporting the grains are distributed. Vi­ sualizations of two-dimensional granular systems [3] demon­ strate weight concentration into “ force chains.” It is natural to expect that similar concentrations of forces will occur in three dimensions. The distinctive forces in bead packs also give rise to distinctive boundary-layer flow [4] and novel sound-propagation properties [5].