Authors

Abstract

To address the issue of missing discrete element simulation parameters for sweet sorghum seeds, this study systematically calibrated their contact parameters using a method combining physical experiments and numerical simulations. First, a discrete element model of sweet sorghum seeds was constructed via 3D scanning and the multi-sphere filling method, and their basic physical parameters were measured (mean triaxial dimensions: 4.51 mm × 3.20 mm × 2.40 mm, density: 1.156 g/cm³, moisture content: 9.8%). The static friction coefficient (0.303), rolling friction coefficient (0.038), and coefficient of restitution (0.534) between the seeds and polylactic acid (PLA) material were calibrated using inclined plane sliding/rolling tests and free-fall collision tests. Based on the physical test results of the dynamic angle of repose (measured value: 34.61°), the inter-seed static friction coefficient and rolling friction coefficient were screened out as significantly influential parameters via a Plackett-Burman test. A quadratic regression model was then used to establish a mapping relationship between parameters and the angle of repose, optimizing to obtain the optimal parameter combination (static friction coefficient: 0.124, rolling friction coefficient: 0.020). Simulation verification showed that under this parameter combination, the simulated dynamic angle of repose was 34.59°, with a relative error of only 0.03% compared to the actual value. The parameter calibration method established in this study features high precision and good repeatability, providing reliable parameter support for the discrete element simulation of sweet sorghum sowing equipment, and holding significant engineering application value for optimizing seed metering device design and reducing seed damage rates.

Abstract in Chinese

针对甜高粱种子离散元仿真参数缺失的问题，本研究通过物理试验与数值模拟相结合的方法，系统标定了其接触参数。首先通过三维扫描和多球填充法构建甜高粱种子离散元模型，并测定其基本物理参数（三轴尺寸均值4.51 mm×3.20 mm×2.40 mm，密度1.156 g/cm³，含水率9.8%）。采用斜面滑动/滚动试验和自由落体碰撞试验，标定种子与聚乳酸（PLA）材料间的静摩擦系数（0.303）、滚动摩擦系数（0.038）和碰撞恢复系数（0.534）。基于动态休止角（实测值34.61°）的物理试验结果，通过Plackett-Burman试验筛选出种子间静摩擦系数、滚动摩擦系数为显著影响参数。通过二次回归模型建立参数与休止角的映射关系，优化得到最优参数组合（静摩擦系数0.124，滚动摩擦系数0.020）。仿真验证表明，该参数组合下动态休止角为34.59°，与实际值相对误差仅0.03%。本研究建立的参数标定方法精度高、可重复性好，为甜高粱播种机具的离散元仿真提供了可靠参数支持，对优化排种器设计、降低种子破损率具有重要工程应用价值。