粉体層の直接せん断試験における粉体粒子の挙動について

抄録

In handling powder materials it is necessary to pay attention to their internal friction as one of their most important properties. The direct shearing test is a simple and useful method to measure the internal friction. However, the behaviours of powder in the direct shearing test procedure are not yet certain, because of the complicated behaviour of particles arising from the shearing action in the powder bed. It must be admitted in any case that the correlation between the internal friction and the σ-τ relation has not yet been sufficiently understood.
This research was undertaken to understand these behaviours of particles in the shearing procedure. For this purpose, these contributions to the σ-τ relation in the distribution of applied normal stress in the powder bed, the weight of the powder under the test, the shearing rate of the test, and the consolidation of powder, etc, were examined with the direct shearing test.
It is concluded from the result of the examinations that the σ-τ relation has material contributions to the change of the particle arrangement in the powder bed in the shearing procedure, and that the deviation of the σ-τ relation from the Coulomb's law τ=μσ+c is due to the relaxation of stress in the shearing plane resulting from the rearrangement of particles in the powder bed. The σ-τ relation should be expressed with the decrease of effective normal stress in the shearing plane in the shearing procedure.
τ=μσ(1-u/σ)+c
where μ; Internal friction
u; Decrease of effective normal stress
c; Cohesive force
Discussion on the correlation between the amount of u and the shapes of σ-τ relations has been made also.