Measurement and Simulation of Wall Friction Behavior of Hard and Soft Pellets

Reliable and accurate measurement of wall friction angle is critical for predicting flow pattern in a bin/silo. The measurement of wall friction is typically performed either using a Jenike tester or a Rotational Shear Tester. In this study, we have investigated the wall friction characteristics of soft and hard polymer pellets on walls with various degrees of roughness and surface treatments. The effect of pellet size and shape has also been investigated.

Rotational shear tester, unencumbered by the limit on shearing distance, provides reliable measurement of wall yield locus. As the pellet-wall friction coefficient increases, the wall yield locus becomes increasingly governed by rolling action of the pellets within the shear tester. We have explored this issue in greater detail – using experimental techniques and DEM simulations.

DEM simulations were performed with PFC-3D package. These simulations provide greater insight into the stress patterns and particle movements within the wall friction tester.