Authors

Abstract

In view of the lack of grain contact parameters that can be used as a reference for the design of key mechanical components such as buckwheat planting, harvesting, and processing, this study combines simulation optimization design experiments and physical experiments to calibrate the parameters of simulated discrete element of buckwheat grains. The non-spherical particle model of buckwheat grains was established using the automatic filling method, and the simulation accumulating test and physical accumulating test were carried out using the bottomless conical cylinder lifting method; the repose angle of buckwheat grains was taken as the response value, and the initial parameters were screened for significance based on the Plackett-Burman test; and a second-order regression model of the error value for the repose angle and the significance parameter was established based on the steepest climb test and Box-Behnken test. On this basis, the minimum error value of the repose angle was used as the goal to optimize the significance parameter, the optimal combination of contact parameters was obtained, and parameter validation tests were carried out. The significance screening test showed that the buckwheat-buckwheat static friction coefficient, the buckwheat-stainless steel rolling friction coefficient, and the buckwheat-stainless steel restitution coefficient had significant effects on the repose angle of buckwheat (P<0.05). The optimization test showed that the buckwheat-buckwheat static friction coefficient was 0.510, the buckwheat-stainless steel rolling friction coefficient was 0.053, and the buckwheat-stainless steel restitution coefficient was 0.492. The validation test showed that the repose angle of buckwheat grain under such parameter was 25.39, and the error with the repose angle of the physical test was 0.55%, which indicated that the optimal parameter combination was reliable. This study could provide a grain model and simulation contact parameters for the research and development of buckwheat sowing, threshing and hulling machinery.

Abstract in Chinese

针对可供荞麦种植、收获、加工等机械关键部件设计参考的籽粒接触参数缺乏的现状，本研究结合仿真优化设计试验与物理试验对荞麦籽粒进行离散元仿真参数标定。采用自动填充法建立了荞麦籽粒非球颗粒模型，并采用无底锥筒提升法进行了仿真堆积试验与物理堆积试验；以荞麦籽粒休止角为响应值，基于 Plackett-Burman 试验对初始参数进行了显著性筛选；基于最陡爬坡试验与Box-Behnken试验建立了休止角误差值与显著性参数的二阶回归模型，此基础上以休止角误差值最小为目标，对显著性参数进行寻优，得到了接触参数最优组合，并进行参数验证试验。显著性筛选试验表明：荞麦-荞麦静摩擦因数、荞麦-不锈钢滚动摩擦因数、荞麦-不锈钢恢复系数对荞麦休止角影响显著（P<0.05）。优化试验表明：荞麦-荞麦静摩擦因数为0.510，荞麦-不锈钢滚动摩擦因数为0.053，荞麦-不锈钢恢复系数为0.492。验证试验表明：此参数下荞麦籽粒休止角为25.39，与物理试验休止角的误差为0.55%，表明最优参数组合可靠。本研究可为荞麦播种、脱粒、脱壳等机械研发提供籽粒模型及仿真接触参数。