Calibration and Experiment of Discrete Element Parameters for White Radish Seed Pods

To investigate the dynamic threshing and separation process of white radish seed pods using the Discrete Element Method (DEM) and improve the accuracy of DEM simulations, a study on parameter calibration for the DEM model of white radish seed pods was carried out through experimental and simulation methods. Firstly, the static friction coefficient and rolling friction coefficient between seed pods and steel plates and between seed pods themselves, as well as restitution coefficient between seed pods and steel plates, were measured using the inclined plane method and the flat plate collision method. The angle of repose test for white radish seed pods was conducted using the funnel accumulation method, and the contour of the angle of repose image was fitted by Origin 2018 software, yielding a measured angle of repose of 31.03°. Key contact parameters between white radish seed pods and operating equipment were determined using the Plackett–Burman design and the steepest ascent method, and the model reliability was verified through the angle of repose test. The results indicated that restitution coefficient, static friction coefficient, and rolling friction coefficient between white radish seed pods and operating equipment were 0.5, 0.488, and 0.025, respectively. The optimal values of restitution coefficient, static friction coefficient, and rolling friction coefficient between white radish seed pods themselves were 0.4, 0.219, and 0.055, respectively. In the angle of repose verification test, the relative error between the simulated and measured values was 2.56%. A DEM-based threshing simulation of white radish seed pods was conducted, achieving a threshing efficiency of 96.47%, with a relative error of 2.24% compared to the actual threshing efficiency. The DEM model of white radish seed pods showed good agreement with the actual situation, and the calibrated DEM simulation parameters were reliable, providing a reference for the DEM simulation studies of white radish seed pods.