Establishment and Parameter Calibration of Quinoa Seed-Soil Contact Model Based on Discrete Element Method

This study provides valuable insights into the interaction between seeds and soil, specifically focusing on quinoa seeds. Accurate discrete element contact models and parameters have been lacking in this area, which has somewhat hindered the optimization and improvement of seeders. By analyzing the collision process between quinoa seeds and soil through contact experiments, the study finds that the adhesive force of the soil on quinoa seeds is much greater than the gravitational force on the seeds and increases with higher soil moisture content. The load-displacement curve obtained from the experiments closely resembles the loading-displacement curve of the JKR (Johnson-Kendall-Roberts) model, leading to the selection of the JKR contact model for simulating the quinoa seed-soil mixture. Using Plackett-Burman experiments, the study identifies the key factors that significantly affect the dynamic angle of repose: soil surface energy, quinoa seed-soil surface energy, and the static friction coefficient between quinoa seeds and soil. Based on the principles of Box-Behnken experimental design, regression analysis and parameter optimization are conducted on these significant factors, resulting in optimal parameter combinations under varying soil moisture content. The verification experiment shows an error of within 1.9%, demonstrating the accuracy of the calibrated parameters. This research provides a solid theoretical foundation for discrete element simulation of seed-soil contact, offering a reference for improving the design and efficiency of seeders.