Calibration of Simulation Parameters of Mung Bean Seeds Using Discrete Element Method and Verification of Seed-metering Test

In order to improve the accuracy of the simulation parameters used in the discrete element simulation test of mung bean precision metering process, and further optimize the metering structure, based on the intrinsic parameters of mung bean seeds, the Hertz Mindlin with bonding model was used to establish the seed simulation model, the simulation parameters between the mung bean seeds and the contact material (plexiglass plate, Somos8000 resin) were calibrated by the free fall collision method, inclined sliding method, and inclined rolling method, respectively. The statistical results showed the collision recovery coefficient, static friction coefficient and rolling friction coefficient between mung bean and plexiglass were 0.445, 0.458 and 0.036, respectively; the collision recovery coefficient, static friction coefficient, and rolling friction coefficient between mung bean and Somos8000 resin were 0.434, 0.556 and 0.049, respectively. Steep climbing test, three-factor and five-level horizontal rotation combinations were designed and tested respectively, involving factors of contact parameters between seeds, and the indices of the relative error between the measured accumulation angle and the simulated accumulation angle. Then, the minimum relative error was taken as the optimization objective, and the test data were optimized and analyzed, the collision recovery coefficient, static friction coefficient, and rolling friction coefficient between mung bean seeds were 0.3, 0.23 and 0.03, respectively. Seeding verification tests were carried out on the calibration results, the statistical results showed that the maximum relative error between the leakage rate of the simulation test and the missing rate of the bench test was 4.71%, the maximum relative error between the reabsorption rate and the multiple rate was 4.94%, and the maximum relative error between the single particle rate and the qualified rate was 0.98%, which proved that the calibration results were reliable. It can provide important reference significance for the design and simulation optimization of mung bean precision metering device. © 2022, Chinese Society of Agricultural Machinery. All right reserved.