宋占华,李浩,闫银发,田富洋,李玉道,李法德.桑园土壤非等径颗粒离散元仿真模型参数标定与试验[J].农业机械学报,2022,53(6):21-33.
SONG Zhanhua,LI Hao,YAN Yinfa,TIAN Fuyang,LI Yudao,LI Fade.Calibration Method of Contact Characteristic Parameters of Soil in Mulberry Field Based on Unequal-diameter Particles DEM Theory[J].Transactions of the Chinese Society for Agricultural Machinery,2022,53(6):21-33.
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桑园土壤非等径颗粒离散元仿真模型参数标定与试验   [下载全文]
Calibration Method of Contact Characteristic Parameters of Soil in Mulberry Field Based on Unequal-diameter Particles DEM Theory   [Download Pdf][in English]
投稿时间:2022-03-18  
DOI:10.6041/j.issn.1000-1298.2022.06.002
中文关键词:  桑园土壤  仿真模型  离散元法  参数标定  非等直径球形颗粒
基金项目:财政部和农业农村部:国家现代农业产业技术体系项目(CARS-18-ZJ0402)和山东省现代农业产业技术体系建设项目(SDAIT-18-06)
作者单位
宋占华 山东农业大学 
李浩 山东农业大学 
闫银发 山东农业大学 
田富洋 山东农业大学 
李玉道 山东农业大学 
李法德 山东农业大学 
中文摘要:为获取土壤离散元仿真模型的土壤颗粒物理参数和接触参数,本文采用试验与仿真相结合的方法,以桑园土壤为例,对土壤颗粒的接触参数进行了仿真标定。首先利用粉体仪、斜面仪、等应变直剪仪等,分析了试验地不同深度土壤的粒径分布,测量了试验地不同深度土壤休止角、滑动摩擦角、剪应力、内聚力、内摩擦角;然后,根据实测土壤粒径分布,利用EDEM软件建立了非等直径土壤球形颗粒模型。在此基础上,以土壤颗粒间及土壤与65Mn钢间的静摩擦因数、滚动摩擦因数、恢复系数为试验因素,土壤休止角、土壤-65Mn钢滑动摩擦角为目标值,建立了基于中心组合试验设计(CCD)方案,并利用Design-Expert软件对仿真试验结果进行了分析,得到了仿真标定的土壤-土壤间静摩擦因数、滚动摩擦因数和恢复系数的最优值分别为0.89、0.45和0.43;标定的土壤-65Mn钢间静摩擦因数、滚动摩擦因数和恢复系数的最优值分别为1.15、0.05和0.4。利用以上标定的最优参数对桑园土壤进行了休止角与滑动摩擦角仿真试验,试验结果表明,休止角仿真值与试验值相对误差为1.69%,土壤-65Mn钢的滑动摩擦角仿真值与试验值相对误差为2.88%。在此基础上,依据实测的土壤剪应力,采用试错法,以实测土壤内摩擦角为目标值,优化标定了土壤-土壤颗粒Hertz-Mindlin with Bonding接触模型中的粘结参数,标定法向粘结刚度、切向粘结刚度分别为1×108、5×107N/m3,临界法向应力和临界切向应力均为10kPa,接触半径为1.1倍颗粒半径,直剪仿真得到内摩擦角为30.24°,仿真值与直剪试验内摩擦角平均值相对误差为5.53%。本文提出的土壤颗粒建模方法、标定方法及其所标定的参数值,可用于砂质壤土桑园耕作机械触土部件与土壤相互作用的离散元仿真分析及其结构优化。
SONG Zhanhua  LI Hao  YAN Yinfa  TIAN Fuyang  LI Yudao  LI Fade
Shandong Agricultural University
Key Words:soil in mulberry field  simulation model  discrete element method  parameter calibration  unequal-diameter sphere particles
Abstract:To obtain the physical parameters and contact parameters of discrete element modelling (DEM) for simulating soil and interaction between soil and soil engaging components in mulberry field, a method combining the experiments and the DEM simulations for calibrating the contact parameters of soil particles in mulberry field was proposed. Firstly, the particle size distribution and physical parameters of soil, such as the angle of repose of soil, sliding friction angle of soil and 65Mn steel, shear stress of soil, cohesion and angle of internal friction of the soils sampled at different depths in the mulberry field, were measured respectively with the powder instrument, inclinometer and equal strain direct shear apparatus. Then an unequal-diameter sphere particles model was built according to the measured particle size distribution by using the EDEM. On this basis, the coefficient of the static friction, coefficient of rolling friction and coefficient of restitution between soil particles and between soil and 65Mn steel were used as test factors, and the angle of repose of soil and the sliding friction angle between the soil and 65Mn steel were used as target values to construct a central combined experimental design (CCD) scheme (three factors and five levels). Subsequently, by analyzing with the Design-Expert software, the simulated optimum values of the coefficient of static friction, coefficient of rolling friction and coefficient of restitution between soils were calibrated to be 0.89, 0.45 and 0.43, respectively; the simulated optimum values of coefficient of static friction, coefficient of rolling friction and coefficient of restitution between soil and 65Mn steel were calibrated to be 1.15, 0.05 and 0.4, respectively. The simulation experiments for verifying the values of the angle of repose of mulberry field soil and the sliding friction angle between the mulberry field soil and 65Mn steel were performed with the simulated parameters such as the coefficient of static friction, coefficient of rolling friction as well as coefficient of restitution. The simulating results showed that the relative errors between the simulating values and the experimental values for the angle of repose and for the sliding friction angle between the mulberry field soil and 65Mn steel were 1.69% and 2.88%, respectively. On the basis of these simulating results, using the soil shear stress gained from the experiments as the judgment standard, the bond parameters of the Hertz-Mindlin with the Bonding contact model for describing the particles of soils were calibrated with the trial and error method with measured soil internal friction angle as the target value. The normal bond stiffness and the tangential bond stiffness were calibrated to be 1×108N/m3 and 5×107N/m3, both of the critical normal stress and the critical tangential stress was calibrated to be 10 kPa, and the contact radius was 1.1 time of radius of the particles, the simulating angle of the internal friction was 30.24°, the relative error between the simulation value and the experimental value of the angle of internal friction was 5.53%.

Transactions of the Chinese Society for Agriculture Machinery (CSAM), in charged of China Association for Science and Technology (CAST), sponsored by CSAM and Chinese Academy of Agricultural Mechanization Science(CAAMS), started publication in 1957. It is the earliest interdisciplinary journal in Chinese which combines agricultural and engineering. It always closely grasps the development direction of agriculture engineering disciplines and the published papers represent the highest academic level of agriculture engineering in China. Currently, nearly 8,000 papers have been already published. There are around 3,000 papers contributed to the journal each year, but only around 600 of them will be accepted. Transactions of CSAM focuses on a wide range of agricultural machinery, irrigation, electronics, robotics, agro-products engineering, biological energy, agricultural structures and environment and more. Subjects in Transactions of the CSAM have been embodied by many internationally well-known index systems, such as: EI Compendex, CA, CSA, etc.

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