Shear Velocity, Shear Test and Flow Velocity

摘要

This paper presents in the first part the use of an annular shear cell to evaluate the infuence of shear test velocity (between 0.8 and 12 mm/s) on the mechanical properties of bulk powders. The results, which are given in terms of changes in yield locus, cohesion, angle of internal friction, flow functions (FF), show that according to Jenike the flowability of the tested powders increases with the shear velocity. In the second part, an experimjental approach is carried on to verify if the above conclusion can be applied to relal flow in hopper. It consists in measuring the flow rate of discharge at the outiet of a square cross-sectional silo with a variable geometry plane flow hopper, and to estimate different shear velocities in the silo during discharging. These results are discussed to see if there is any relation between shear velocity between particles during silo discharging and shear velocity during mechanical shear tests.