On distribution of contact forces in random granular packings

In an earlier paper, Ngan (Phys. Rev. E 68 (2003) 011301) proposed a statistical mechanics-based theory to predict the mathematical form of the probability force distribution of contact forces in stressed granular packings. However, the wrong choice of the mean-force constraint in that work leads to unsatisfactory prediction in the 3D situation, although the 2D prediction is very accurate. The present work shows that a different mean-strain constraint chosen for the force distribution can yield the correct prediction when compared to computer simulation results in both 2D and 3D. Furthermore, new simulation results are used to verify the interpretation that the shape of the force distribution, measured by a parameter κ in the predicted force distribution, is a structure-sensitive term