ESTABLISHMENT AND CALIBRATION OF DISCRETE ELEMENT MODEL OF KING GRASS STALK BASED ON THROWING TEST

In order to better use the discrete element method (DEM) to study the cutting and throwing process of King Grass (KG) stalk in mechanical harvesting, the DEM model and contact parameters of KG stalk were studied in this paper. By using the Multi-sphere method, the DEM model of KG stalk was established in EDEM software. Through the impact bounce test and slope sliding test, the stalk-steel coefficient of static friction, stalk-steel coefficient of restitution and stalk-stalk coefficient of restitution were calibrated as 0.372, 0.656 and 0.523, respectively. Based on the stacking test, using the response surface methodology, the optimal values of stalk-stalk coefficient of static friction, stalk-stalk coefficient of rolling friction, stalk-steel coefficient of rolling friction were calibrated as 0.393, 0.072 and 0.144, respectively. The throwing test bench of stalk was designed, and the actual and simulation throwing test were carried out. The relative error of throwing distance in bench test and simulation test under four throwing speeds was 1.15%, 7.76%, 8.88% and 10.46%, respectively. The throwing trajectory curve of the simulation test is consistent with that of the actual test, which verifies the accuracy of the DEM model and contact parameters of KG stalk.