Authors

Abstract

To address the challenge of parameter accuracy in discrete element method (DEM) simulations of buckwheat seeds within a seed metering device, this study characterized the physical properties of buckwheat seeds and subsequently calibrated the simulation model parameters. Initially, physical experiments were conducted to determine the triaxial dimensions, angle of repose, and static friction coefficients of buckwheat seeds against stainless steel surfaces. A three-dimensional model of the buckwheat seeds was then generated using Inventor and it was imported into EDEM to simulate the seed stacking process, with the angle of repose quantified via image processing techniques. Employing a Plackett-Burman design, initial parameters were screened, identifying the static friction coefficient between buckwheat seeds, the rolling friction coefficient between buckwheat seeds, and the static friction coefficient between buckwheat seeds and stainless steel as significant factors influencing the angle of repose. The optimal range for these significant parameters was determined through a steepest ascent experiment, and a second-order regression model was developed using Box-Behnken experimental results to optimize the angle of repose and the identified parameters. The optimized parameter set comprised a static friction coefficient between buckwheat seeds and stainless steel of 0.448, a rolling friction coefficient between buckwheat seeds of 0.038, and a static friction coefficient between buckwheat seeds of 0.372. Validation through both simulations and physical experiments revealed a relative error of 1.08%, confirming the reliability of the calibrated parameters for simulating buckwheat seed sowing machinery.

Abstract in English

针对荞麦种子在排种器中进行离散元排种仿真模拟试验缺乏准确参数的问题，本研究对荞麦种子进行物性参数测定及仿真模型参数标定。首先,通过物理试验测定荞麦种子的三轴尺寸，休止角以及荞麦种子与不锈钢板间静摩擦系数。其次,运用Inventor绘制荞麦种子的三维模型，并导入到EDEM中建立荞麦离散元模型，来模拟荞麦种子的堆积过程，通过图像处理技术，获得准确的休止角。通过Plackett-Burman试验对初始参数进行筛选，得出荞麦间静摩擦系数、荞麦间滚动摩擦系数、荞麦-不锈钢之间的静摩擦系数对颗粒堆休止角影响显著。最后在最陡爬坡试验确定显著性参数最优值区间的基础上，根据Box-Behnken试验结果建立了休止角与显著性参数的二阶回归模型并对其进行优化，得到显著性参数的最佳组合。通过试验得出荞麦－不锈钢静摩擦系数为 0.448 、荞麦间滚动摩擦系数为 0.038 、荞麦间静摩擦系数为 0.372 。通过仿真与物理试验对比验证，得到二者相对误差为1.08%，标定参数可为荞麦播种机械仿真提供数据依据。