Stability of a pile of grains with non-uniform mass

AGUIRRE, M.; MARTINO, R.; GEMINARD, J.-C; PIVA, M.

Puerto Varas

Workshop; Southern Workshop on Granular Materials 2018 - SWGM 2018; 2018

Facultad de Ciencias Físicas y Matemáticas de la Universidad de Chile

We study the stability of granular systems constituted by particles with non-uniform distribution of mass which lead to a displacement of the center of mass with respect to their geometrical center. This is a factor that has not been previously analyzed even though present in many practical situations, e.g. seeds and pharmaceutical capsules partially filled with powder. Moreover, in the case of pharmaceutical capsules, the possible motion of the inner powder introduces an internal degree of freedom, i.e. mobile center of mass. In particular, we present experimental results concerning the stability of two-dimensional piles of hollow plexiglass cylinders containing an inserted smaller metallic rod. These particles partially fill a rough-edged drum whose rotation produces successive avalanches. The distribution of avalanche sizes and characteristic angles of the pile, i.e. maximum angle of stability and angle of repose, are analyze for systems where the inserts are fixed or free to roll.