Force Fluctuations in Bead Packs

Science  28 Jul 1995:
Vol. 269, Issue 5223, pp. 513-515
DOI: 10.1126/science.269.5223.513


Experimental observations and numerical simulations of the large force inhomogeneities present in stationary bead packs are presented. Forces much larger than the mean occurred but were exponentially rare. An exactly soluble model reproduced many aspects of the experiments and simulations. In this model, the fluctuations in the force distribution arise because of variations in the contact angles and the constraints imposed by the force balance on each bead in the pile.