Calibration of discrete element parameters and the modelling of silo discharge and bucket filling

The discrete element method (DEM) is a promising approach to model machine–granular material interaction. The accuracy of DEM models depends on the model parameters. In this study a calibration process is developed to determine the parameter values. Laboratory shear tests and compressions tests are used to determine the material internal friction angle and stiffness, respectively. These tests are repeated numerically using DEM models with different sets of particle friction coefficients and particle stiffness values. The shear test results are found to be dependent on both the particle friction coefficient and the particle stiffness. The compression test results show that it is only dependent on the particle stiffness. The combination of shear test and compression test results can be used to determine a unique set of particle friction and particle stiffness values. The calibration process is validated by modelling silo discharge and bucket filling. It is shown that DEM can accurately predict the silo discharge rate and flow patterns. It is also shown that DEM can predict bucket forces, fill rates and fill patterns.