Authors

Abstract

In order to obtain accurate contact parameters for foxtail millet seeds in discrete element method (DEM) simulations, this study selected the Jinmiao K10 variety as the research object. Physical experiments and DEM simulations were integrated to calibrate the contact parameters. First, the restitution coefficient, static friction coefficient, and rolling friction coefficient between foxtail millet seeds and polylactic acid (PLA) material were measured using methods such as free-fall and inclined plane tests. Subsequently, based on the experimentally measured repose angle of 21.93°, a Plackett–Burman design was employed to screen the key parameters significantly influencing the repose angle. These included the inter-seed static friction coefficient, rolling friction coefficient, and restitution coefficient. The steepest ascent test was then conducted to determine the direction of parameter optimisation. A quadratic regression model was established using the Box–Behnken response surface methodology to determine the optimal combination of contact parameters: restitution coefficient of 0.512, static friction coefficient of 0.22, and rolling friction coefficient of 0.041. These parameters were imported into EDEM software for simulation validation. The simulated repose angle is 22.2°, with a relative error of 1.23%, demonstrating high accuracy and practical applicability of the calibrated parameters. This study provides reliable simulation parameter support for the design and optimization of critical components in foxtail millet seeding machinery.

Abstract in Chinese

为获取谷子种子在离散元仿真种精确的接触参数，本文以金苗K10谷子品种为研究对象，结合物理实验与离散元仿真方法开展接触参数标定研究。首先通过自由落体法、斜面法等方法测得谷子种子与PLA材料间的碰撞恢复系数、静摩擦系数及滚动摩擦系数范围；随后基于实际休止角角测量结果（21.93°），采用Plackett-Burman试验筛选出对休止角影响显著的关键参数，包括种间静摩擦系数、滚动摩擦系数和碰撞恢复系数；进一步通过最陡爬坡试验确定参数优化方向，并利用Box-Behnken响应面法建立二次回归模型，求解最优接触参数组合：种子间碰撞恢复系数为0.512，静摩擦系数为0.22，滚动摩擦系数为0.041。将该组合导入EDEM软件进行仿真验证，所得休止角为22.2°，相对误差为1.23%，表明标定参数具有较高精度和实用性。研究成果可为谷子播种机械关键部件的设计与优化提供可靠的仿真参数支持。