Professional Articles

Development of a Shear Cell for Measuring the Wall Friction of Bulk Solids with a Ring Shear Tester

To calculate silos and to conduct comparison and flowabilty measurements, the flow properties of powders and bulk solids must be measured. For this purpose, mainly so-called shear testers are used. The Jenike shear tester [1], a translatory shear tester, is frequently employed in practical applications. A disadvantage of this device is its limited shear displacement that, for very elastic (e.g. silicas, PE powder), compressible and coarsegrained bulk solids [2,3], is often not sufficient to properly consolidate the bulk solid. Another disadvantage is that the sample must be preconsolidated by hand, which requires a great deal of experience and practice, and that the measurements are rather time-consuming. Because of its construction, the Jenike shear tester hardly allows measurements at consolidation stresses smaller than approximately 2,5 kPa [4], as may occur near the discharge opening of a silo.