Emmanuel Baidhe, Clairmont L. Clementson
Discrete element methods (DEM) provide an opportunity for thorough analysis of postharvest handling of high moisture corn (above 21%). Accurate DEM predictive simulations, however, require precise parameter (inter-particle and particle-surface frictional properties) calibration. Most parameter values available in the literature are based on corn at moisture levels <21%wb. It is therefore important to evaluate and establish suitable contact parameters for high moisture corn. This study sought to evaluate the influence of contact parameters and particle shape (custom polyhedron, sphero-polygon, and polyhedron) on the bulk properties (bulk packing height and filling static angle of repose, AOR) to facilitate the numerical analysis of high moisture corn. The study leverages existing literature on contact parameters to optimize the DEM parameters relevant for the accurate prediction of bulk properties of high moisture corn. Calibration and optimization of contact model parameters were done with the custom polyhedron particle and applied to the other particle shapes. The effect of particle shape on bulk packing height and static AOR formation was also determined. Response surface analysis yielded the following optimal contact parameters values: interparticle static coefficient of friction (COF) = 0.606, interparticle coefficient of restitution (RC) = 0.566, particle-to-plastic COF = 0.479, particle-to-plastic RC = 0.624, particle-to-plastic rolling resistance (RR) = 0.078, particle-to-steel COF = 0.19, and particle-to-steel RR = 0.0018. Overall, the custom polyhedron particle and sphero-polygon particle had more accurate prediction of the bulk height compared to the polyhedron. The custom polyhedron particle was a better predictor of the static AOR than the two built-in particles shapes. The particle displacement and kinetic velocities by particle shape were in the order of polyhedron > sphero-polygon > custom polyhedron. All particles presented bulk height and static AOR with a relative error of <12%, demonstrating the robustness of the optimal contact parameter for simulation of high moisture corn.