Discrete element simulation modeling method and parameter calibration of sugarcane segment

Objective  The construction method of discrete element model and the setting of simulation parameters of sugarcane segment as stalk material with large length and diameter ratio are not clear, the accuracy of the model has a great influence on the dynamic response characteristics between particles, and the accuracies of the simulation parameters need to be improved by parameter calibration.

Method  Taking the physical repose angle of sugarcane segment as the response value, the discrete element parameters were optimized and calibrated by simulation test method. Firstly, the basic physical parameters of sugarcane segment were measured by physical test, and the sugarcane segment simulation model was constructed based on the multi-sphere polymerization model and XML method. Then, the Plackett-Burman test was used to screen the significance of eight initial parameters in the discrete element simulation of sugarcane segment, and the optimal value ranges of significant parameters were determined by the steepest ascent search test. Further, the second-order regression equation between the significant parameters and repose angle was established based on the Box-Behnken test, and taking the physical repose angle of 42.70° as the target value, the regression equation was optimized.

Result  The significance screening test showed that the Poisson’s ratio of sugarcane segment, the static and dynamic friction coefficients between two sugarcane segments had significant influence on the simulated repose angle. The optimal parameter combination was as follows: The Poisson’s ratio of sugarcane segment was 0.35, the static and dynamic friction coefficients between sugarcane segments were 0.53 and 0.04 respectively. The simulation test results of the optimal parameter combination showed that there was no significant difference between the simulated repose angle and the physical repose angle, and the relative error between them was 0.99%, which further verifies the reliability of sugarcane segment parameters calibrated by discrete element method.

Conclusion  The sugarcane segment discrete element model and the optimal simulation parameters can be used in the sugarcane segment discrete element simulation test, and can provide a reference for calibration of the discrete element parameter of stalk agricultural materials with large length and diameter ratio.