Faculty of Modern Agriculture Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, China.
School of Energy and Environment Science, Yunnan Normal University, Kunming, Yunnan Province, China.
PLoS One. 2024 Jul 15;19(7):e0300516. doi: 10.1371/journal.pone.0300516. eCollection 2024.
To improve the accuracy of the Hami melon discrete element model, the parameters of the Hami melon seed discrete element model were calibrated by combining practical experiments and simulation tests. The basic physical parameters of Hami melon seeds were obtained through physical experiments, including triaxial size, 100-grain mass, moisture content, density, Poisson's ratio, Young's modulus, shear modulus, angle of repose, suspension speed and various contact parameters. Taking the repose angle of seed simulation as an index, the parameters of each simulation model were significantly screened by the Plackett-Burman test. The results showed that the recovery coefficient, static friction coefficient and rolling friction coefficient of Hami melon seeds had significant effects on repose angle. Based on the steepest climbing test and quadratic regression orthogonal rotation combination test, it was determined that the significant order of the influence of various contact parameters on the angle of repose was static friction coefficient, collision recovery coefficient, and rolling friction coefficient. The optimal parameter combination was obtained through the mathematical regression model between the angle of repose and various contact parameters, namely, the collision recovery coefficient of Hami melon seeds was 0.518, the static friction coefficient of Hami melon seeds was 0.585 and the rolling friction coefficient of Hami melon seeds was 0.337. Under this condition, three static seed-dropping experiments and dynamic rolling accumulation experiments were carried out. The average simulated angle of repose was 31.93°, and the relative error with the actual value was only 1.71%. The average simulated rolling accumulation angle was 51.98°, and the relative error with the actual value was only 1.92%.
为提高哈密瓜离散元模型的准确性，通过结合实际试验和模拟试验对哈密瓜籽离散元模型的参数进行标定。通过物理试验得到哈密瓜籽的基本物理参数，包括三轴尺寸、百粒质量、含水率、密度、泊松比、杨氏模量、剪切模量、休止角、悬浮速度和各种接触参数。以种子模拟休止角为指标，采用 Plackett-Burman 试验对各模拟模型的参数进行显著筛选。结果表明，哈密瓜籽的恢复系数、静摩擦系数和滚动摩擦系数对休止角有显著影响。基于陡度爬坡试验和二次回归正交旋转组合试验，确定了各种接触参数对休止角影响的显著顺序为静摩擦系数、碰撞恢复系数和滚动摩擦系数。通过休止角与各种接触参数的数学回归模型，获得最优参数组合，即哈密瓜籽碰撞恢复系数为 0.518、哈密瓜籽静摩擦系数为 0.585、哈密瓜籽滚动摩擦系数为 0.337。在此条件下，进行了 3 次静态投种试验和动态滚动堆积试验。模拟的休止角平均为 31.93°，与实际值的相对误差仅为 1.71%。模拟的滚动堆积角平均为 51.98°，与实际值的相对误差仅为 1.92%。
