Evolution of the force distributions in jammed packings of soft particles

The evolution of the force distributions during the isotropic compression of two-dimensional packings of soft frictional particles is investigated numerically. Regardless of the applied deformation, the normal contact force distribution P(f(n)) can be fitted by the product of a power law, and a stretched exponential, while the tangential force distribution P(f(t)) is fitted well by a Gaussian. With increasing strain, the asymptotic behavior at large forces does not change, but both P(f(n)) and P(f(t)) exhibit a broadening, even though, when scaled with the average forces, their widths decrease. Furthermore, the distribution of friction mobilization P(η) is a decreasing function of η=|f(t)|/(μf(n)), except for an increased probability of fully mobilized contacts (η=1). The excess coordination number of the packings increases with the applied strain, indicating that the more a packing is compressed the more stable it becomes.