Calibration of discrete element model parameters for maize kernel based on response surface methodology

Objective  The discrete element method (DEM) is commonly used in simulating the motion states of agricultural materials in agricultural production process. The accuracy of discrete element simulation depends on the parameters used in simulation process. In this study, we calibrated DEM parameters to provide a reliable basis for the application of DEM in simulation experiment.

Method  Using maize kernel as object and repose angle as response value, the discrete element calibration method based on response surface methodology was proposed after the comparison of simulation experiment results adopting different parameter combinations with prototype experiment results. Plackett-Burman experiment was performed to test the significance of discrete element parameters and screen the parameters that significantly influenced response value. Then the steepest ascent experiment was used to ascertain the optimum value ranges of significant parameters. Finally, central composite designs were used to design response surface modifying experiments consisting of three factors and five levels.

Result  Corn Poisson's ratio and corn-corn static friction coefficient interacted significantly with each other. The best parameter combination was corn Poisson's ratio 0.438, corn-corn static friction coefficient 0.182 and corn-corn static rolling coefficient 0.051. The simulation experiments were conducted using calibrated parameters above and the mean value of repose angle was 26.89°, approximately to the value in prototype experiment.

Conclusion  The discrete element parameter calibration method for maize kernel based on response surface methodology is feasible, and can improve the accuracy of maize kernel discrete element simulation test.