Calibration Method of Friction Coefficient of Granular Fertilizer by Discrete Element Simulation

Whether the contact parameters between materials are set correctly affects the reliability of the results of discrete element simulation test. At present, the calibration method of contact parameters in discrete element simulation is still in the exploratory stage. Plackett-Burman multi-factor significance screening test was carried out for four kinds of particle characteristics test methods: split cylinder method, tilt method, drawing plate method and inclined plane method. The analysis of variance of test results showed that the significant factors and factors influencing the measurement results were different from each other. According to the results of variance analysis of split cylinder method, inclined method and inclined plane method, a method of friction coefficient calibration based on the overall characteristics of particulate materials was proposed. The simulation test was combined with the real test, and the static friction coefficient between the urea particles and the PVC material was 0.41, the static friction coefficient between the particles was 0.36, and the rolling friction coefficient between the particles was 0.15. The calibrated coefficients were validated by the bottomless cylinder method. The angle of repose simulation test results was 30.57 degrees, the real test results was 31.74 degrees and the relative error was 3.69%. Under different water content conditions, the relative error between the actual test angle of repose and the simulated angle of repose under the calibrated coefficients was not greater than 4.59%. There was no significant difference between the simulation results and the real test results. The validity of the calibration coefficients was verified by the test results. This method can be used to calibrate the friction coefficient of other granular materials. © 2020, Chinese Society of Agricultural Machinery. All right reserved.