Authors

Abstract

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.

Abstract in Chinese

针对目前水稻秸秆离散元模型的关键接触参数尚未完全优化，限制了离散元模型在水稻秸秆处理设备设计中的应用效果等问题。本研究借助EDEM软件构建了水稻秸秆离散元模型开展接触参数标定，通过开展水稻秸秆的物理尺寸，堆积角以及水稻秸秆-水稻秸秆、水稻秸秆-钢板间的摩擦系数测试试验，采用图像处理结合最小二乘法来获得水稻秸秆的堆积角。通过Plackett －Burman试验筛选出对堆积角影响显著的接触参数，得出水稻秸秆间碰撞恢复系数、水稻秸秆间静摩擦系数、水稻秸秆间滚动摩擦系数对水稻秸秆颗粒堆休止角影响显著。采用Box-Behnken设计（Box-Behnken Design）建立接触参数与休止角之间的二阶响应模型，结合响应曲面法进行目标寻优，获取最优接触参数组合。并进行堆积角验证试验，试验表明仿真堆积角与实际物理堆积角相对误差值为2.13%。结果证明所标定参数可用于水稻秸秆接触行为的模拟，能够对水稻秸秆处理过程的离散元仿真模拟提供理论和数据支持。