Experimental determination of friction coefficient and mobilization force for a laterally confined granular column

Abstract

The case of a cylindrical container filled with granular material is a basic situation where the presence of the cylindrical wall induces horizontal pressure and hence, shearing forces (caused by friction between the container wall and the granular bed). Under certain circumstances, a finite length of the granular column in a housing cylindrical container can stand in the vertical position unsupported at the bottom end, held only by the frictional forces at the wall. When an axial load is applied at one end of the bed and increased slowly, the whole granular column starts to slide at a critical load value, called herein the mobilization force. Since this scenario is of significant practical interest (e.g. in caissons construction or in the design of silos), the experimental determination of the related parameters is of great importance for the development of suitable simulation models. In this paper, experimental methodologies for in-situ measurement of the mobilization force and the Coulomb's friction coefficient between the granular material and the wall of the housing cylinder are presented in detail. Practical and convenient experimental set-ups that require only a few pieces of readily available and easily operated test equipment are proposed to measure these parameters. Results from a series of example experiments conducted on a granular alumina bed packed in a rigid plastic cylinder illustrate the performance and validity of the proposed experimental methods.

Measurement of Restitution and Friction Coefficients for Granular Particles and Discrete Element Simulation for the Tests of Glass Beads

“…Malla et al measured the friction coefficient between the particle and the cylinder wall for a laterally confined granular column [5]. Han et al investigated the friction coefficient between elliptical particles and inclined plate by measuring the inclination angle of particles on inclined plates [6].…”

Dust Eruptions

“…This force is balanced by gravity acting on the beads πR 2 ρ s gdz and the friction of the wall 2πRµP s dz where µ is the coefficient of friction. µ is known to vary between 0.31 and 0.39 according to Malla 2007 [46]. While here we have taken the container to be circular, the geometry of the container does not change the analysis.…”