PARAMETER CALIBRATION AND VALIDATION OF A STRAW-SOIL DISCRETE ELEMENT MODEL IN HUANG-HUAI-HAI WHEAT STUBBLE FIELDS

In order to improve the accuracy of discrete element simulation of stubble cleaning soil-engaging parts of corn planter in wheat stubble field, taking the soil straw of Huang-Huai-Hai as the research object, the method of combining physical repose angle with EDEM simulation test was adopted, and the Hertz-Mindlin with bonding contact model was selected to calibrate the simulation contact parameters. Plackett-Burman was used to screen out the main factors that had a significant impact on the test indicators. Design-Expert was used to conduct a central combination test on the screening factors, and regression analysis and significance test were performed on the simulation results to find out the optimal combination of test indicators. The factor screening test showed that the primary and secondary factors affecting the soil repose angle were soil rolling friction factor, soil-device static friction factor, soil static friction factor and soil normal stiffness per unit area. The primary and secondary order of the factors affecting the straw repose angle was the device-straw rolling friction coefficient, the device-straw restitution coefficient, and the straw static friction coefficient. The significant test showed that the soil rolling friction coefficient was 0.574, the soil static friction coefficient was 0.93, the soil-device static friction coefficient was 0.373, the soil normal stiffness per unit area was 9.5×109, and the relative error between the optimized parameter simulation test and the actual test was 3.1%. The straw static friction coefficient was 0.598, the device-straw restitution coefficient was 0.754, the device-straw rolling friction coefficient was 0.11, and the relative error between the optimized parameter simulation test and the actual test was 1.45%.