Effects of Particle Size and Surface Roughness on Wall Friction of Particulate Materials

摘要

The effects of varying the fines fraction, the packing geometry and the particle surface roughness on the measured and calculated wall friction coefficients were investigated. Experimental measurements using a Direct Shear Box were carried out with mono-size beds of coarse particles (d > 1mm) under different types of packing conditions (square and hexagonal), and repeated after the addition of the maximum possible amount of fine material into the packing at different particle size ratios. The experimental results were compared with analytical calculations based on the Adhesion Theory of Friction. The stress distributions prevailing within the bulk assembly were calculated using a finite element computer code; ANSYS. The relationship between the wall friction coefficient and the compressive stress tends to be strongly affected by the surface roughness of the constituent particles, while varying fines fraction and packing geometry appears to have negligible influence.