| 机施有机肥散体颗粒离散元模型参数标定 |
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| 引用本文： | 袁全春,徐丽明,邢洁洁,段壮壮,马帅,于畅畅,陈晨.机施有机肥散体颗粒离散元模型参数标定[J].农业工程学报,2018,34(18):21-27. |
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| 作者姓名： | 袁全春 徐丽明 邢洁洁 段壮壮 马帅 于畅畅 陈晨 |
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| 作者单位： | 中国农业大学工学院 |
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| 基金项目： | 现代农业产业技术体系建设专项资金资助（CARS-29） |
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| 摘 要： | 针对有机肥离散元模型接触参数和接触模型参数难以通过查阅文献或试验直接获得的问题,该文提出一种通过仿真试验建立回归模型并结合物理试验寻优的方法,对有机肥离散元模型参数进行标定。考虑到有机肥颗粒间的凝聚力,选择"Hertz-Mindlin with Johnson-Kendall-Roberts"接触模型。应用Plackett-Burman Design对有机肥离散元模型参数进行筛选,得到对休止角有显著影响的参数,即有机肥-有机肥滚动摩擦系数、表面能JKR和有机肥-钢板滚动摩擦系数;通过最陡爬坡试验确定了显著性参数的最优值区间,应用Central Composite Design建立并优化了休止角与显著性参数的回归模型,以实际休止角为目标,求解得到显著性参数最优值,即有机肥-有机肥滚动摩擦系数为0.10,JKR为0.015,有机肥-钢板滚动摩擦系数为0.11。在标定的参数下进行仿真验证试验,仿真休止角与实际休止角的相对误差为0.42%,无明显差异,表明标定的参数准确,可以为有机肥离散元模型参数的选取提供参考。
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| 关 键 词： | 模型 肥料 离散元 参数标定 凝聚力 休止角 |
| 收稿时间： | 2018/2/1 0:00:00 |
| 修稿时间： | 2018/6/12 0:00:00 |
Parameter calibration of discrete element model of organic fertilizer particles for mechanical fertilization |
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| Yuan Quanchun,Xu Liming,Xing Jiejie,Duan Zhuangzhuang,Ma Shuai,Yu Changchang and Chen Chen.Parameter calibration of discrete element model of organic fertilizer particles for mechanical fertilization[J].Transactions of the Chinese Society of Agricultural Engineering,2018,34(18):21-27. |
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| Authors: | Yuan Quanchun Xu Liming Xing Jiejie Duan Zhuangzhuang Ma Shuai Yu Changchang and Chen Chen |
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| Institution: | College of Engineering, China Agricultural University, Beijing 100083, China,College of Engineering, China Agricultural University, Beijing 100083, China,College of Engineering, China Agricultural University, Beijing 100083, China,College of Engineering, China Agricultural University, Beijing 100083, China,College of Engineering, China Agricultural University, Beijing 100083, China,College of Engineering, China Agricultural University, Beijing 100083, China and College of Engineering, China Agricultural University, Beijing 100083, China |
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| Abstract: | Abstract: As the parameters of discrete element model for organic fertilizer are difficult to obtain directly from literatures or experiments, this study proposed a method to calibrate the parameters based on tests of the angle of repose. Firstly, a physical test was carried out. The diameters of organic fertilizer particles were between 0.25 and 2 mm, the fertilizer moisture was 13.7%, and the organic fertilizer was crushed to meet the requirements of uniformity of fertilization. In the test, in order to obtain the organic fertilizer heap, the cylinder was lifted up by a universal testing instrument at a speed of 20 mm/s. Then, the angle of repose of the fertilizer was measured with inclinometer and the test was repeated for 10 times, as the mean angle of repose was 38.15°. Secondly, the simulation test was carried out. Considering the cohesion characteristics between particles of organic fertilizer, the contact model of Hertz-Mindlin with Johnson-Kendall-Roberts was used in simulation modeling. Since the organic fertilizer particles were near-spherical, the basic model of the software default was adopted to simulate organic fertilizer granules. In the simulation test, the relative error was 2.22% by comparing the angle of repose formed by a variety of particle sizes according to actual particle size distribution and the angle of repose formed by the same particle size (1 mm). Therefore, a basic sphere model with a radius of 1 mm was used and the three-dimension geometry model built by SolidWorks was imported into the simulation software, with the cylinder lifting speed was 20 mm/s, the total number of particles was 10 000, the generation rate was 2 000/s, the fixed time step was 22% of Rayleigh time step, the target save interval was 0.01 s, and the cell size was 2 mm. Not all discrete element model parameters of organic fertilizer had significant impact on the angle of repose, so a screening through Plackett-Burman Design was made. The results showed that rolling friction coefficient between organic fertilizer, surface energy (JKR) and rolling friction coefficient between organic fertilizer and steel plate had significant impact on angle of repose. The optimal value interval of the there significant parameters was determined by the steepest ascent test, and built the linear regression model of angle of repose through Central Composite Design. The fitting of the linear regression model was optimized by adding the quadratic term and cubic term of rolling friction coefficient between organic fertilizer with the fitting of the regression model had a great improvement, and the P value of the lack of fit was improved from 0.091 to 0.405 6. Thirdly, the optimal value of the significant parameters was obtained with the actual angle of repose as a goal, with the rolling friction coefficient between organic fertilizer was 0.10, the JKR was 0.015, and the rolling friction coefficient between organic fertilizer and steel plate was 0.11. Finally, in order to verify the accuracy of the calibrated parameters, the simulation verification test of the calibration parameters was carried out, and the relative error between the simulated angle of repose and the actual angle of repose is 0.42%, which meant that the calibration parameters were accurate. This study can provide reference for the selection of discrete element model parameters of organic fertilizer. |
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| Keywords: | models fertilizers discrete element method calibration of parameters cohesion angle of repose |
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