Validation of a DEM Model for Predicting Grain Damage in an Industrial-Scale Handling System

An industrial-scale handling system with a flight conveyor, a screw conveyor, and a rethresher as the core components was designed and built to validate a previously developed discrete-element-method-based (DEM) grain impact damage model. Corn and soybean samples were processed by the system at three impeller speeds and two feed rates, and the amount of damage caused by handling was evaluated. DEM simulations with the impact damage model were performed for the same test conditions. The experimental results showed that grain damage increased with increasing impeller speed and decreasing feed rate, which aligned with the simulation predictions. The damage fraction values estimated by the simulation were larger than the experimental measurements when the original DEM input parameters were used. The mean absolute error between the simulation and experimental results was 0.14 for the corn tests and 0.05 for the soybean tests. This overprediction may be because the particle-geometry coefficient of restitution (PG COR) was measured at low impact speeds but impact speeds in the validation system is high. The simulation predictions can be significantly improved by decreasing the PG COR from 0.75 to 0.55 for the corn and from 0.6 to 0.4 for the soybeans. The mean absolute error between the simulation and experimental results decreased from 0.14 to 0.02 for the corn tests and from 0.05 to 0.01 for the soybean tests after the reduction of PG COR. In addition, the sensitivity analysis suggested that the Young's modulus and particle shape contribute only minor changes to the damage fraction and the location of the damage for the conditions examined.