Simulation of grain–straw separation by Discrete Element Modeling with bendable straw particles

• A construction of bendable straw particles in DEM is proposed.
• The particles are calibrated with realistic straw properties.
• DEM of grain–straw separation with these particles matches with experimental data.
• A sensitivity study of grain–straw separation w.r.t. crop properties is performed.
• Crop property influence can be related to straw coverage and grain kernel diameter.

The combine harvester owes its name to the integration of the whole chain of grain harvesting steps in one machine. Running these interdependent processes simultaneously requires insight in the influence of crop factors and adjustments on the individual processes and the consequences for downstream processes. This paper introduces changes to the Discrete Element Method (DEM) in order to be suitable for the simulation of grain–straw separation, which is one of the most critical processes in the combine harvester. Segmented bendable straw particles have been constructed in the DEMeter++ simulation environment and their physical properties have been calibrated with realistic straw properties. The use of these particles for modeling separation has been validated by reconstructing an existing separation experiment by Beck (1992) in DEMeter++ and comparing the simulation result with the experiment. Once validated, the practical use of the simulation framework to assess the sensitivity of separation to crop properties is illustrated.