摘要
为了进一步提升基于离散元法对免耕作业机具与土壤互作关系研究的准确性,以华北麦玉两熟区免耕壤土为研究对象,基于离散元软件(Discrete Element Modeling,DEM)扩展的The Edinburgh Elasto-Plastic Adhesion非线性弹塑性接触模型开展常年免耕农田土壤离散元仿真模型参数标定研究。应用Plackett-Burman设计敏感性分析试验,选择对土壤压板试验沉陷量影响显著的关键参数(即土壤颗粒恢复系数、土壤颗粒-颗粒静摩擦系数、土壤颗粒表面能和土壤颗粒-颗粒塑性变形比),以土壤压板试验沉陷量为评价指标,应用Box-Behnken试验建立了沉陷量与4个显著性参数的二次多项式回归模型,以物理试验得到的实际沉陷量6.2 mm为目标值,对显著性参数进行寻优,得到最优组合为:土壤颗粒恢复系数为0.47,土壤颗粒-颗粒间静摩擦系数为0.62,土壤颗粒表面能为6.12 J/m^(2),土壤颗粒塑性变形比为0.41。最后通过标定优化的参数进行土壤颗粒应力传递试验,与室内试验结果对比发现,仿真的土壤颗粒接触传力特性与实际土壤压实过程中应力传递差别较小,误差范围在9.21%以内,并对比分析仿真和实测的土壤应力传递特性曲线的拟合情况,两者之间的决定系数R^(2)为0.91,表明两条曲线的拟合相似度较高,验证了免耕土壤参数标定的准确可靠,参数标定后的离散元免耕土壤模型精确度高。研究可为快速构建免耕模式下的土壤离散元模型及免耕农机装备优化提供技术支撑。
No-tillage technology has been widely used for the sustainable development in the modern agriculture.But the perennial no-tillage has caused great changes in the soil mechanics.The elastoplastic mechanical properties of no-tillage soil can also lead to the unclear interaction mechanism between agricultural machinery and soil.A Discrete Element Method(DEM)can be expected to serve as an important technique to clarify the interaction.However,two great challenges still remain on the selection of the soil particle contact model and the calibration of the parameters.In this study,a nonlinear elastoplastic contact model was proposed for the no-tillage soil compaction using the Extended DEM(EDEM).The no-tillage loam was collected from the two cropping wheat-maize regions in North China.The parameters were calibrated under the compaction damage caused by external forces in farmland.A sensitivity analysis was designed using a Plackett-Burman technique,in order to select the key parameters,including the coefficient of soil particle recovery,the coefficient of static friction between soil particles,the surface energy of soil particles,as well as the plastic deformation ratio of soil particles to particles.Taking the amount of subsidence as the evaluation index,a quadratic polynomial regression model was established using the Box-Behnken test.The significance parameters were then optimized,where the actual subsidence of 6.2 mm was taken as the target value obtained from the soil plate test under the condition of 12.7 kN load.An optimal combination of parameters was obtained as follows:the recovery coefficient of soil particles was 0.47,the coefficient of static friction between soil particles and particles was 0.62,the surface energy of soil particles was 6.12 J/m^(2),and the plastic deformation ratio of soil particles was 0.41.In this case,the soil DEM model was obtained for the long-term no-tillage.Five repeated tests were set for the pressure plate settlement test,where the model settlement amounts were 7.19,6.50,5.55,6.62,and 6.07,respectively.The relative error was 2.84%,compared with the actual measurement.The results showed that there was a smaller subsidence error of DEMs simulation and laboratory test.A field test was performed on the soil particle stress transfer,further to calibrate the obtained parameters.It was found that there was little difference between the simulated and the measured parameters,where the relative error was within 9.21%.The determination coefficient R^(2) between the two fitting curves was 0.91,indicating a higher fitting similarity.Consequently,higher accuracy and reliability were achieved for the parameter calibration of no-tillage soil.This finding can provide promising technical support for the rapid construction of the soil DEM model under no-tillage mode for the optimal agricultural equipment.
作者
王宪良
钟晓康
耿元乐
魏忠彩
胡红
耿端阳
张祥彩
Wang Xianliang;Zhong Xiaokang;Geng Yuanle;Wei Zhongcai;Hu Hong;Geng Duanyang;Zhang Xiangcai(College of Agricultural Engineering and Food Science,Shandong University of Technology,Zibo 255000,China;School of Mechanical Engineering,Xihua University,Chengdu 610039,China;Sichuan Modern Agricultural Equipment Engineering Technology Research Center,Chengdu 610039,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第23期100-107,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金青年科学基金项目(32101631)
四川省现代农业装备工程技术研究中心开放课题(XDNY2021-001)。
关键词
土壤
离散元
模型
免耕
压实
参数标定
应力传递
soils
discrete element
models
no-till
compaction
parameter calibration
stress transfer
