Coarse graining of adhesive elasto-plastic DEM contact models in quasi-static processes

In general, input parameters of Discrete Element Method (DEM) simulations are calibrated by minimizing the difference of simulations output and laboratory measurements. To produce comparable bulk responses, in general, these (calibration) simulations replicate laboratory setup and procedures at a scale of 1:1. In terms of volume of bulk material, there is a considerable difference between laboratory experiments and large scale industrial applications, such as grab ship unloaders. For that reason, DEM simulations of large scale industrial applications often lead to an extreme computation time, especially for fine bulk materials. To reduce the computation time, scaling techniques can offer a solution.
In this paper, a scaling method with the focus on an adhesive elasto-plastic DEM contact model is established. The scaling method is based on extending the coarse graining principles described in [1]. In the coarse graining, original DEM particles are substituted by larger grains. We establish the relationship between the scaling factor and the contact settings. Furthermore, the influence of the coarse graining on bulk properties in the quasi-static regime processes, such as the ring shear test, is investigated. The adequacy of the proposed scaling method is confirmed for both the simulated bulk materials as well as the interaction with the bulk handling equipment. Using the developed scaling method, virtual prototyping of bulk handling equipment and its interaction with cohesive materials can be done with a practical computational cost.