Granular Force Chain Network — Stress Heterogeneity

Force chains (Liu et al. 1995, Nature): granular stress is not distributed uniformly — it travels along "chains" of strongly loaded contacts, leaving "weak" grains nearly unstressed. The force distribution P(f) ~ exp(−f/f̄) for large forces.

Chain geometry depends on packing fraction, polydispersity, and friction. Bright contacts = large contact force.