This paper discusses a comparison of the data of experiments obtained by using different shear tests methods in order to examine the confidence in the results of experiments on the flow properties of a bulk solid.
The angle of internal friction of dry granular materials, which has been measured by both a tri-axial shear tester and a fixed volume direct shear tester, increases with a decrease in the voidage of the specimen. Except for the extremely dense and loosely packed states, the experimental results of the angle of internal friction agree within about 3 degrees. There is however a difference of 3 to 5 degrees for a material in which the particle shape is deflective.
The flowability index of cohesive powders and wet materials is expressed by a ratio of the unconfined yield strength to the bulk density. The results of experiments on the flowability index are independent of the unconfined yield and direct shear tests.

^† This report was originally printed in J. Soc. Powder Technology, Japan, 23(9), 678-684 (1986) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.