Computational Viscoelastoplastic DEM Modeling and Simulation of Wheat Stubble-Soil Mechanics: Integrated Adhesion Model, Hybrid Calibration and Field Validation for Precision No-Till Planter Optimization

Abstract Traditional rigid discrete element method (DEM) models fail to accurately characterize the viscoelastoplastic deformation and fracture of wheat stubble under mechanical loading. To address this limitation, a bonded viscoelastoplastic DEM framework was developed by integrating Hertz-Mindlin with Bonding V2 and the JKR cohesion model. Key mechanical and interfacial properties of wheat residues were quantified through systematic experiments. Tensile strength reached 4.82×10⁶ Pa, shear strength 4.72×10⁶ Pa and shear modulus 1.0×10⁷ Pa. Interfacial parameters for stubble-straw, stubble-steel and stubble-soil interactions were determined via collision, friction and pull-out tests. A hybrid calibration strategy combining the steepest ascent method, Box-Behnken design and response surface methodology optimized critical bonding parameters: normal critical stress of 3.10×10¹⁰ Pa, tangential critical stress of 3.01×10⁶ Pa and bonding radius of 0.77 mm. The resulting shear-force prediction error against physical tests was only 3.4%. The coupled DEM-FEM model was validated through soil bin tests and field experiments in Henan Province. In soil bin tests, simulated blade shaft torque (130.97 N·m) showed a 4.27% relative error compared with measured values (136.81 N·m), and the seed-zone stubble clearance rate (72.34%) differed from test results (70.41%) by 2.74%. Field experiments yielded an average blade shaft torque of 167.32 N·m and a seed-zone stubble clearance rate of 78.34%, both aligning closely with simulation and soil bin test data. This study develops a robust deformable stubble model that improves DEM accuracy for no-till seeding applications. It provides a theoretical foundation and practical tool for optimizing conservation agriculture machinery components and determining energy-efficient operating parameters, thereby mitigating crop residue-related operational challenges in the Huang-Huai-Hai region.