Abstract: Feature parameters between the white radish seed particles and planting machinery were still lacking, particularly on the contact parameters between the white radish seed particles and mechanized planting machinery. Discrete element method (DEM) is widely used to simulate the key work process and provides a powerful theoretical reference for parameter calibration of solid particles and agricultural materials. Taking white radish seed particles as the research object, this study is aimed to establish a discrete element model using threedimensional scanning reverse simulation in the EDEM software, and then to calibrate parameters of white radish seed particles through physical experiments and virtual simulation experiments. The collision restitution coefficient, static friction coefficient and rolling friction coefficient between the white radish seed particles and 4 different materials of ABS plastic, stainless steel plate, plexiglass and aluminum alloy were determined by collision bounce test, inclined plane slip test and inclined plane rolling test, respectively. These coefficients of restitution were 0.48, 0.62, 0.51, and 0.44, respectively. The coefficients of static friction were 0.50, 0.42, 0.45, and 0.48, respectively. The coefficients of rolling friction were 0.014, 0.025, 0.007, and 0.006, respectively. The multivariate quadratic equation was optimized with multiple objectives. The optimal combination of contact parameters of the discrete element model between white radish seeds was obtained. The collision recovery coefficient, the static friction coefficient and the rolling friction coefficient were 0.19, 0.54 and 0.02, respectively. The accumulation test of the physical angle of repose of white radish seed particles was carried out by the cylinder lifting method. MATLAB was used to carry out a grayscale and binarization processing on these accumulation images of stacking angle, and these angles of repose of white radish seed particles and ABS plastic, stainless steel plate, plexiglass and aluminum alloy were 33.48°, 32.72°, 33.81°, and 29.88°, respectively. The angle of repose errors obtained by the simulation test and the physical test were 1.4%, 3.2%, 2.6% and 2.8%, respectively. These results showed that the discrete element simulation parameters obtained from the modeling and calibration of white radish seed particles were accurate and reliable, which could provide a theoretical reference for the discrete element simulation research of white radish seed particles.

Key words: white radish seed, discrete element method, contact parameter, calibration, seed metering device, plant machinery

摘要： 针对白萝卜种子颗粒本征参数、颗粒与种植机械装备间接触参数缺乏等问题，以白萝卜种子颗粒为研究对象，利用三维扫描逆向建模技术与EDEM软件建立白萝卜种子颗粒离散元模型，通过物理试验与虚拟仿真试验对仿真参数进行标定。采用碰撞弹跳试验、斜面滑移试验和斜面滚动试验确定白萝卜种子颗粒与ABS塑料、不锈钢板、有机玻璃和铝合金4种不同材料之间的碰撞恢复系数、静摩擦系数和滚动摩擦系数，碰撞恢复系数分别为0.48、0.62、0.51、0.44，静摩擦系数分别为0.50、0.42、0.45、0.48，滚动摩擦系数分别为0.014、0.025、0.007、0.006；通过响应曲面和DesignExpert软件的优化模块对多元二次方程进行多目标优化，获得白萝卜种子间离散元模型接触参数较优组合：碰撞恢复系数0.19、静摩擦系数0.54、滚动摩擦系数0.02。采用圆筒提升法进行白萝卜种子颗粒物理休止角堆积试验，利用MATLAB对堆积图像处理获得物理堆积试验白萝卜种子颗粒与ABS塑料、不锈钢板、有机玻璃和铝合金的休止角分别为33.48°、32.72°、33.81°、29.88°，仿真试验与物理试验得到的休止角误差分别为1.4%、3.2%、2.6%和2.8%。研究结果表明，白萝卜种子颗粒建模和标定所得的离散元仿真参数具有准确可靠性，可为白萝卜种子颗粒离散元仿真研究提供理论参考。

关键词: 白萝卜种子颗粒, 离散元法, 接触参数, 标定, 排种器, 种植机械