Calibration and Verification of Coated Caragana korshinskii Seeds Based on Discrete Element Method

The accurate modeling of seed motion characteristics is crucial for optimizing seed-metering devices in agricultural machinery. This study investigated the physical properties and contact parameters of coated Caragana korshinskii seeds through a combined approach of calibration experiments and verification tests. Physical experiments were conducted to measure basic parameters including seed dimensions, density, moisture content, and angle of repose. The Plackett–Burman experimental design was employed to screen significant parameters affecting seed motion, followed by the Path of Steepest Ascent method and Response Surface Methodology to establish optimal parameter combinations. Results identified three key parameters: seed-to-seed coefficient of restitution (0.221), seed-to-seed static friction coefficient (0.337), and seed-to-aluminum static friction coefficient (0.117). Verification tests using a 4BQD-40 broadcast seeder demonstrated good agreement between simulation and physical experiments, with relative errors of 1.56% for the angle of repose. Seeding efficiency showed consistent results between calibration (354 g/min) and verification tests (347 g/min), while breakage rates remained within acceptable ranges (2.3% predicted vs. 4.1% actual). The established parameter set provides a reliable foundation for discrete element simulation of coated Caragana korshinskii seed motion in metering devices, contributing to the optimization of seeding equipment design.