二重円筒式内筒回転型剪断試験機内の環状粉粒体充てん層の底圧および側圧の測定

抄録

Side-wall pressure distributions and bottom pressures of annular powder beds in a double-cylinder rotary shear tester have been measured under both the dynamic (the inner cylinder is rotating) and static (the inner cylinder is stationary) conditions for a variety of powders. The effects of the powder bed height, the diameters of annular bed, and the rotational speed of the inner cylinder on the side-wall pressure distribution along the bed height and the bottom pressure have been examined. Janssen's equation applied to only the satatic cases with small bed heights and large outer cylinder diameters and did not hold in the dynamic cases where anomalously high pressures obtained in comparison with the static pressures. The ratio of the static sideall to bottom pressures (the static pressure coefficient) was always less than unity and the bed was in an active state in the vertical direction. The dynamic pressure coefficient, however, increased to greater than unity as the bed height increased, and the bed under the dynamic condition changed gradually from active to passive states in the vertical direction.
These findings should be considered if the internal friction factor of a powder is to be measured properly by a double-cylinder rotary shear tester.