Force transmission in three-dimensional hexagonal-close-packed granular arrays submitted to a point load

In this article, the aluminium-plastic board and carbon paper technique are combined to investigate the contact force at bottom boundary of three-dimensional ordered granular arrays in response to a point load. Arching effects were observed with all arrays, and the force distribution markedly depends on the crystal structure and has a 120°-symmetry at every layer of the crystals， while the heterogeneity in force distribution in the pure hcp arrays is minimal of all the arrays. Non-main force chains were observed to have the “focalization" phenomena. These results can be explained by a force-transmission model.