有机无机混合肥料离散元参数标定方法研究

Study on discrete element parameter calibration method for organic inorganic mixed fertilizers

[目的]在有机无机混合肥料仿真试验中,传统参数标定方法待标定参数多,标定过程复杂。本文根据有机肥对无机肥颗粒黏附特性,提出一种新的离散元仿真接触参数标定方法。[方法]利用自由落体碰撞试验、静摩擦试验、滚动摩擦试验对复合小球和钢的接触参数进行校准;设计Plackett-Burmen Design试验、爬坡试验和Box-Behnken响应面试验,得到混合肥料接触模型最优参数,通过堆积角对比试验、有机肥和无机肥混合比例预测试验、撒肥盘颗粒分布对比试验验证最优参数。[结果]复合小球与钢的最优碰撞恢复系数、静摩擦系数和滚动摩擦系数分别为0.323、0.776、0.255;有机肥肥料之间最优碰撞恢复系数、静摩擦系数和滚动摩擦系数分别为0.40、0.70、0.14;有机肥与钢板之间的最优碰撞恢复系数、静摩擦系数和滚动摩擦系数分别为0.44、0.70、0.15;Hertz-Mindlin with JKR模型参数为0.017。最优参数进行对比验证堆积角的相对误差为1.05%,最优参数能预测不同混合比例肥料的堆积角,撒肥盘抛撒试验列分布最大相对误差为35.95%,平均误差15.86%。[结论]试验结果验证了标定方法正确性,同时为后续有机肥-无机肥-机械互作系统研究提供依据。

[Objectives]In order to solve the problem of multiple contact parameters and difficult calibration of organic and inorganic mixed fertilizer,according to the adhesion characteristics of organic fertilizer to inorganic fertilizer particles,a new calibration method of contact parameters for discrete element simulation was proposed in this paper.[Methods]The contact parameters between the composite ball(TCB)and steel were calibrated using free fall collision tests,static friction tests,and rolling friction tests.The Plackett-Burmen Design test,slope climbing test,and Box-Behnken response surface test were designed to obtain the optimal parameters of the mixed fertilizer contact model.The optimal parameters were verified through the stacking angle comparison test,mixing proportion of organic fertilizer to inorganic fertilizer prediction test,and fertilizer tray particle distribution comparison test.[Results]The optimal collision recovery coefficient,static friction coefficient,and rolling friction coefficient between TCB and steel were 0.323,0.776 and 0.255,respectively.The optimal collision recovery coefficient,static friction coefficient,and rolling friction coefficient among organic fertilizers were 0.40,0.70 and 0.14,respectively.The optimal collision recovery coefficient between organic fertilizer and steel plate were 0.44,0.70 and 0.15 for static and rolling friction coefficients,respectively.The Hertz-Mindlin with JKR model parameter was 0.017.Comparison of the optimal parameters verified that the relative error of the stacking angle was 1.05%,and the optimal parameters could predict the stacking angle of different mixed proportion fertilizers.The maximum relative error of the distribution of the fertilizer tray throwing test column was 35.95%,and the average error was 15.86%.[Conclusions]The experimental results verified the correctness of the calibration method,and provided a basis for subsequent research on the organic fertilizer-inorganic fertilizer-mechanical interaction system.