Determination of discrete element model parameters for hilly red soil and validation through spiral opener performance analysis

Establishment of discrete element model of hilly red soil is an important means to carry out the interaction mechanism of soil tillage components and optimize the tillage components. The Hertz–Mindlin with bonding model was selected as the discrete element model for the hilly red soil due to its viscosity and ease of consolidation. To calibrate the parameters of the discrete element model, simulation experiments were designed based on the Box–Behnken experimental method to determine both angle of response (AOR) and penetration resistance (PR). The results indicate that the AOR is 40.67º with a soil–soil coefficient of restitution, coefficient of static friction, and coefficient of rolling friction of 0.594, 1.159, and 0.193, respectively; the PR is 517.11 N with a soil shear modulus, soil–steel coefficient of static friction, and critical normal stress of 10.1 MPa, 0.457, and 14.892 kPa, respectively; and the relative error of AOR and PR between simulation and actual measurements is 2.22 and 2.48%, respectively. Finally, the discrete element model was verified through ditching simulation and field experiment using a spiral opener. The results show that the relative error of resistance torque between simulation and field experiments is 2.18%; the relative errors of ditch depth, height of soil ridge on the left and right sides, and soil throwing distances on the left and right sides between simulation and field experiments are 4.68, 3.96, 10.24, 5.99, and 10.64%, respectively.