Modelling and simulation of the grain threshing process based on the discrete element method

Abstract A modelling and simulation method was developed to comprehensively describe and quantify the unmeasurable dynamic threshing process based on the discrete element method (DEM). To establish a simulation model of rice plants, experiments were carried out to determine the relevant biological and mechanical parameters. A discrete element model of rice plants was established using hollow cylindrical elastic bonds. The complex threshing process of grain was simulated. Through the threshing simulation, the dynamic behaviour of flexible rice plants under large deformation, fragmentation and multiple interaction conditions was accurately described at the particle level. The cumulative distribution of the separated grains obtained by the simulation was consistent with the experimental results. The maximum relative error of the grain separation rate between the simulated and experimental results under different feeding rates was 11.2%. The impact force distribution, grain flow field distribution, threshed grain percentage and grain separation rate during the threshing process could be easily obtained by the simulation. The threshing simulation could predict the effects of the feed rate, cylinder speed, threshing gap and rolling friction on the threshing performance.

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