Dem-Based Calibration of Soil Contact Parameters Prior to Grapevine Burying

To address the lack of simulation parameters when applying discrete element simulations to guide the optimal design of grapevine burying machines, this study focused on the soil conditions in Xinjiang. The soil was divided into three layers, and the static and dynamic angle of repose characteristics of each layer were investigated using the Hertz-Mindlin with Johnson-Kendall-Roberts (JKR) contact model. First, the Plackett-Burman test was used to eliminate parameters that had no significant effect on the static and dynamic angles of repose. Then, the steepest ascent test was applied to narrow the parameter ranges, followed by the Box-Behnken test to develop regression models between the repose angles and the significant parameters. The results showed that the soil-soil restitution coefficient, soil-soil rolling friction coefficient, soil-steel static friction coefficient, and JKR surface energy were the key parameters influencing the static and dynamic repose angles. Experimental validation demonstrated that the average relative errors between the simulated and measured angles of repose using the optimized parameters were 0.92% and 0.32%, respectively, confirming the validity of the selected parameters. This study provides an important reference for the design optimization of grapevine burying machines and for discrete element simulation of other cohesive particulate materials.