Powder Technology, Vol.374, 22-32, 2020
Calibration of cohesive DEM parameters under rapid flow conditions and low consolidation stresses
Discrete Element Method (DEM) is a well-established and validated tool for the simulation of bulk materials. However, a lot of questions still need answering in the domain of cohesion and adhesion. This paper will present a calibration approach using the draw down test. This test generates several test results which could be used for the calibration and is one of the standard tests for the calibration of cohesionless materials. For the bulk material wet sand (10% moisture) is used. It is shown how the draw down test can be used to determine a unique set of friction, rolling resistance and cohesion values to reproduce the real behaviour of wet sand. For the DEM simulation the JKR model, one of the most widely used cohesion models, was used. It considers surface energy density and increased particle overlap to explain cohesion. The ambiguity associated with surface energy or interfacial energy is tackled by developing thorough calibration procedures which will help in fine tuning these parameters. Further, the rolling resistance model used for the simulation of cohesive materials is discussed. Calibration results for the very widely used modified elastic-plastic spring dashpot rolling resistance model are compared to an adhesive hysteric rolling resistance model. (C) 2020 Elsevier B.V. All rights reserved.
Keywords:Granular materials;Cohesive DEM calibration;JKR;Adhesive hysteretic rolling resistance;Draw down test;Wet sand