Scaling of the angle of repose test and its influence on the calibration of DEM parameters using upscaled particles

The numerical effort of computer simulations based on the Discrete Element Method (DEM) forces an idealisation of the DEM models especially when industrial problems are analysed. The idealisation often includes the scale-up of the particle sizes and therefore requires the adaption of contact model parameters to produce realistic simulation results. Hence, the calibration of contact parameters is the most crucial part in the development process of a DEM model. Due to the scale-up of particle size, a calibration test should provide results invariant to test dimensions and particle size. This paper shows how the results of one typical calibration test, the angle of repose (AoR) test using a lifting cylinder, are invariant regarding the dimensions of the test rig and the considered partide size distribution. The lifting velocity of the cylinder is indicated as a parameter which influences the AoR Hence, the cylinder pull-up test delivers only size invariant results for materials in static stress state when slow lifting velocities are applied. The so called shear box test will be presented as an alternative AoR test to achieve invariant results even for a dynamic, fast flowing stress state and short test durations. (C) 2018 Elsevier B.V. All rights reserved.