颗粒肥料离散元仿真摩擦因数标定方法研究

对分体圆筒法、倾斜法、抽板法和斜面法4种颗粒特性测试方法进行Plackett-Burman多因素显著性筛选试验,试验方差分析结果表明,不同的测试方法影响测量结果的显著因素与因素显著程度。根据分体圆筒法、倾斜法和斜面法的方差分析结果,提出一种基于颗粒物料整体特性的摩擦因数标定方法,将仿真试验与真实试验相结合,依次标定出尿素颗粒与PVC材料间静摩擦因数为0. 41,颗粒间静摩擦因数为0. 36,颗粒间滚动摩擦因数为0. 15。将所标定的摩擦因数采用无底圆筒法进行验证试验,休止角仿真试验结果为30. 57°,真实试验结果为31. 74°,相对误差为3. 69%,不同含水率下的实际试验休止角与所标定摩擦因数下的仿真休止角相对误差均不大于4. 59%,仿真试验结果与真实试验结果无显著差异,验证了所标定摩擦因数的有效性。本方法可用于其他颗粒状物料间摩擦因数的标定试验。

Calibration Method of Friction Coefficient of Granular Fertilizer by Discrete Element Simulation

Whether the contact parameters between materials are set correctly affects the reliability of the results of discrete element simulation test. At present, the calibration method of contact parameters in discrete element simulation is still in the exploratory stage. Plackett-Burman multi factor significance screening test was carried out for four kinds of particle characteristics test methods: split cylinder method, tilt method, drawing plate method and inclined plane method. The analysis of variance of test results showed that the significant factors and factors influencing the measurement results were different from each other. According to the results of variance analysis of split cylinder method, inclined method and inclined plane method, a method of friction coefficient calibration based on the overall characteristics of particulate materials was proposed. The simulation test was combined with the real test, and the static friction coefficient between the urea particles and the PVC material was 0.41, the static friction coefficient between the particles was 0.36, and the rolling friction coefficient between the particles was 0.15. The calibrated coefficients were validated by the bottomless cylinder method. The angle of repose simulation test results was 30.57 degrees, the real test results was 31.74 degrees and the relative error was 3.69%. Under different water content conditions, the relative error between the actual test angle of repose and the simulated angle of repose under the calibrated coefficients was not greater than 4.59%. There was no significant difference between the simulation results and the real test results. The validity of the calibration coefficients was verified by the test results. This method can be used to calibrate the friction coefficient of other granular materials.