Parameters Calibration of Red Clay Soil in Hilly Area of Southwest China for Discrete Element Simulation Based on Repose Angle Test

Abstract

Its southwest's rugged and mountainous terrain has thick soil, which causes high resistance, poor efficiency, and sometimes even the impossibility to operate agricultural equipment. Using discrete element simulation, a cutting-edge technical technique, it is possible to optimize the agricultural machinery elements that come into contact with the soil in order to reduce drag and increase efficiency. Although there are presently no precise and trustworthy discrete element modeling parameters for red clay, the physical characteristics of red clay in the hilly and mountainous regions of the southwest are unique. As a result, in this study, the soil moisture content was 12.5%1% and 18.3%1%, respectively, for the actual working environment of the soil moisture content of 10%–20% in the hilly and mountainous areas of southwest China, and the experiment's measurement of the accumulation angle was 38.54°. This subject of the study was clay. To calibrate the appropriate model's physical characteristics, use the Hertz-Mindlin with JKR contact model in the EDEM simulation software. Prior to simulating the accumulation angle of soil particles, the intrinsic physical parameter values of the red loam soil are first obtained through actual experiments. The range of soil contact mechanical parameters in the GEMM database is then used to determine the optimal value interval of the contact parameters determined by the steepest slope test. In order to determine the regression model of the soil accumulation angle, the quadratic regression rotation orthogonal combination test is used to obtain the second-order regression model of the accumulation angle and the significant parameters. The significant parameters are then optimized using the actual accumulation angle as the target. In the end, it was found that the following contact mechanics characteristics worked well together in the EDEM simulation test: JKR surface energy 8 J/m2, restitution coefficient 0,35, dynamic friction coefficient 0,13, and static friction coefficient 0,56. The relative inaccuracy determined by the actual physical test is 1.80%, and the stacking angle is 39.24°. The study's findings demonstrate that the method has a high degree of calibration accuracy and is both reasonable and useful for calibrating soil discrete element simulation parameters. The pertinent calibration parameters can serve as a technological foundation for investigating machine-soil interaction and machine-tool optimization research in southwest China's hilly and mountainous regions.