Calibration and test of discrete element model (DEM) for compound fertilizer particles in mechanized variable-rate application

Abstract Background In order to obtain accurate discrete element simulation model (DEM) parameters of compound fertilizer and solve the problem of measuring parameters of contact mechanical properties of fertilizer particles, this study measured the intrinsic parameters and contact parameters of compound fertilizer particles through physical tests and established a simulation model that corresponds with the actual to solve the problem of challenging measurement of contact parameters of compound fertilizer particle. Results By using the Blackett-Burman test, the parameters that had a significant impact on the compound fertilizer's resting angle were determined to be the fertilizer-fertilizer collision recovery coefficient, fertilizer-fertilizer rolling friction coefficient, and fertilizer-steel static friction coefficient. Utilizing the steepest ascent test, the ideal value intervals for the three key parameters were identified. The Box-Burman response surface analysis was used to establish and optimize the regression model of the rest angle and significant parameters. With the actual rest angle as the target value, the best combination of significance parameters was found, which was used for the simulation verification test. The simulated rest angle is 20.61°, whereas the real rest angle was 19.95°, with a relative error of 3.31%. Conclusion The results demonstrate that the calibration parameters are essentially accurate representations of the real characteristics, which can serve as a reference point for simulation research and optimization design of variable fertilizer spreader.