Abstract:

Accurately obtaining the discrete element simulation model parameters of organic fertilizer for Camellia oleifera seed meal （COSM） is the key for optimizing the design of the COSM fertilization device using simulation methods. Taking the COSM with water content of 2.88% as the research object， and “Hertz-Mindlin with JKR” in EDEM software as the contact model， the range of static friction coefficient and rolling friction coefficient between COSM and stainless steel were determined by a friction coefficient meter. Other parameters that were difficult to measure， such as the Poisson's ratio and shear modulus of COSM， were obtained by contact friction test combining the GEMM material library， to provide a horizontal selection for the Plackett-Burman test. Through the Plackett-Burman experiment， 3 from 9 parameters were selected that more significantly impacted stacking angle including COSM， the static friction coefficient of COSM-COSM， the static friction coefficient of COSM-stainless steel and the rolling friction coefficient of COSM-COSM. Then， according to the results of the steepest climbing test to further using the organic fertilizer accumulation angle of COSM as the response value， a second-order regression model was obtained based on the Box-Behnken experiment to determine the accumulation angle and significance parameters.Using the stacking angle of 35.42° measured in physical experiments as the response target， seek the optimal solution to the regression equation， and the optimal parameter combination was obtained as： the static friction coefficient of COSM-COSM of 1.01， the static friction coefficient of COSM-stainless steel of 0.34， and the rolling friction coefficient of COSM-COSM of 0.20. The simulation experiments of stacking and mold hole compression were conducted under the condition of optimal solutin， it was found thatthe relative error between the simulated stacking angle and the physical test results was found to be 2.96%， and the stacking shape had a high degree of similarity. The relative error between the simulated extrusion force and the actual die hole compression test was 1.79%， which verified that the calibrated parameters were accurate.The research results provided theoretical references for analyzing the complex interaction between the COSM and fertilizer equipment and designing a high-efficiency and precise fertilizer equipment.

Key words: seed meal in camellia oleifera, resting angle, organic fertilizer, discrete element, parameter calibration

摘要：

准确获取油茶茶枯有机肥的离散元仿真模型参数是运用仿真手段优化设计油茶茶枯施肥装置的关键。以含水率为2.88%的油茶茶枯为研究对象，选用EDEM软件中的“Hertz-Mindlin with JKR”作为接触模型，以圆筒提升法物理实验堆积角度为响应目标，通过响应面法优化标定了油茶茶枯有机肥的仿真参数。首先通过接触摩擦试验并结合GEMM材料库得出其他难以测量的参数，如COSM的泊松比和剪切模量，进而为Plackett-Burman试验提供选择水平。通过Plackett-Burman试验从油茶茶枯有关的9个参数中筛选出了3个对堆积角影响较为显著的参数：茶枯-茶枯静摩擦系数、茶枯-不锈钢静摩擦系数、茶枯-茶枯滚动摩擦系数。根据最陡爬坡试验结果确定显著性参数最优值区间，进一步以茶枯有机肥堆积角为响应值，基于Box-Behnken试验获得堆积角与显著性参数的二阶回归模型。以物理试验测得的堆积角度35.42°为响应目标对回归方程寻求最优解，得到最佳参数组合为：茶枯-茶枯静摩擦系数1.01，茶枯-不锈钢静摩擦系数0.34，茶枯-茶枯滚动摩擦系数0.20。采用最优解进行堆积和模孔压缩仿真试验，仿真堆积角与物理试验结果的相对误差为2.96%，且堆积形状具有高度相似性，仿真挤压力与实际模孔压缩试验的挤压力相对误差为1.79%，验证了所标定的参数的准确性。研究结果可为分析茶枯有机肥与施肥装置间复杂的相互作用并设计出高效精准茶枯有机肥施肥机提供理论参考。

关键词: 油茶茶枯, 堆积角, 有机肥, 离散元, 参数标定