RESEARCH ON CONTACT PARAMETER CALIBRATION AND EXPERIMENT OF DISCRETE ELEMENT SIMULATION MODEL FOR RICE STRAW

Considering the current suboptimal calibration of critical contact parameters in the discrete element model (DEM) for rice straw, which consequently limits the applicability of DEM in the design of rice straw processing machinery, this study developed a DEM of rice straw using EDEM software to accurately calibrate the contact parameters. The physical dimensions and the repose angle of rice straw, as well as the friction coefficients between rice straw-rice straw and rice straw-steel plate were determined through physical experiments. Image processing combined with the least squares method was employed to obtain the angle of repose of rice straw. The Plackett-Burman experimental design was selected to screen the contact parameters that significantly influence the repose angle. The results indicated that the coefficient of restitution between rice straw particles, the static friction coefficient between rice straw particles, and the rolling friction coefficient between rice straw particles have a significant effect on the angle of repose of the granular pile. A Box-Behnken design (BBD) was used to establish a second-order response surface model between the contact parameters and the angle of repose. The optimal combination of contact parameters was obtained by performing target optimization using response surface methodology (RSM). A validation experiment for the repose angle was conducted, and the results indicated a relative error of 2.13% between the simulated angle of repose and the physical angle of repose. The result demonstrates that the calibrated parameters can be used for simulating the contact behavior of rice straw and can provide theoretical and data support for the discrete element simulation of the rice straw processing process.