MEASUREMENT OF PHYSICAL PROPERTY PARAMETERS AND SIMULATIVE CALIBRATION OF DEM PARAMETERS FOR GREEN ONION SEEDS

The contact parameters setting determines the accuracy of discrete element method (DEM) simulation analysis, while there is a lack of research on contact parameters of green onion seed. In this paper, the physical parameters of green onion seeds were measured by experiment, and the DEM parameters were calibrated by simulation. Based on EDEM software, the Hertz-Mindlin no-slip model was used to create the particle model of green onion seeds that takes on the shape of peltate with the irregular surface, and the repose angle was measured by the measurement method of lifted cylinder. Plackett-Burman test was designed to screen the significance of parameters, and the optimal range of significance parameters was further determined through the steepest climbing test. Then the regression model of seeds repose angle was obtained by Box-Behnken test and the optimal parameter combination was calculated: the static friction factor between seeds was 0.424, the rolling friction factor was 0.085, the static friction factor between seeds and steel was 0.310. The optimized repose angle in the simulation had an overall relative error of 0.54%, indicating that the contact parameters of the calibrated green onion seed had high accuracy.