Abstract
The effects of packing structure of powder on the angle of repose were studied. The results are as follows: the angle of repose increases when the powder is packed more densely, the angle of repose is small when the particles are spherical, becomes larger with an increase in irregularity of the particles' shape, and attains its largest with the needle like particles. This effect appears to be due to the entanglement of particles.
When the sample is composed of spherical particles of uniform size, the angle of repose is especially small. In order to examine this phenomena, model experiments with steel balls were used. The results show that a little irregularity or hole in the packing structure gives a great effect on the angle of repose. Moreover, it was found that the friction force between the particles and their substratum on which the particles were heaped had great influence upon the occurrence of the irregularity in structure. The friction force between the powder bed and the material of substratum and the angle of repose of powder were measured. The results show generally an increase in the angle of repose with increasing friction force up to a certain value, after which there is a small increase of the angle of repose with increased friction force.
An experimental equation was obtained showing the relation of these values.
