基于离散元法的旋耕刀受力分析  

Force analysis of rotary blade based on distinct element method

作　　者：方会敏[1,2] 姬长英[1] 张庆怡[1] 郭俊[1] 

机构地区：[1]南京农业大学工学院,南京210031 [2]山东省农业机械科学研究院,济南250100

出　　处：《农业工程学报》2016年第21期54-59,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(51275250);江苏省2013年度普通高校研究生科研创新计划项目(CXZZ13_0282)

摘　　要：为分析旋耕刀在有秸秆覆盖和无秸秆覆盖土壤中工作时的受力情况,该文采用离散元法构建土壤-旋耕刀相互作用和秸秆-土壤-旋耕刀相互作用的三维离散元模型。在土槽试验中采用扭矩传感器测量旋耕刀所受扭矩,在仿真中导出每个时刻旋耕刀受到的扭矩和力数据,试验和仿真都在恒定前进速度0.222 m/s和耕作深度100 mm及4种转速77、100、123、146 r/min下进行。结果显示旋耕刀最大扭矩值随着转速增加呈现增加的趋势;在无秸秆覆盖土壤中,试验值与仿真值的相对误差为16.3%;在有秸秆覆盖土壤中二者相对误差为19.1%。耕作过程中旋耕刀所受合力、水平力及侧向力都呈现先升后降的趋势;合力、水平力和垂直力的最大值,都随着转速的增加而增加。旋耕刀刚开始切土时,在有秸秆覆盖的土壤中受到的阻力总比无秸秆覆盖的土壤中所受阻力要大;之后旋耕刀在有秸秆覆盖的土壤中受到的最大力要大于在无秸秆覆盖的土壤中受到的最大力。仿真的水平力和垂直力与旋耕刀理论模型计算得到的旋耕刀水平力和垂直力变化一致。利用离散元法研究旋耕刀切土过程,对探讨刀具与土壤的相互作用机理及设计和优化高秸秆含量土壤中工作的耕作机械具有重要意义。Tillage practice is one of the energy-consumed links in agricultural production, while the energy can be saved through proper management of tillage practices. In order to manage the tillage process reasonably, a better understanding of soil-tool interaction should be developed. In fact, the soil-tool interaction is a complex process because of the spatial variability of soil, tool dynamics and soil movement. The process becomes more complex due to the addition of straw, as straw-soil-tool interaction involves the incorporation, displacement and movement of straw. Basically, soil-tool interactions are usually characterized by forces arising at the soil-tool interface. In case of rotary tillage, the force variation of rotary blade plays a pivotal role in the field of blade geometry optimization and energy consumption. However, it is very difficult to acquire this information in field tests due to the presence of many uncontrollable variables such as weather and soil moisture content. The simulation of tillage process by a rotary blade using distinct element method（DEM） is hypothesized to provide a better understanding of the force variation in complex field conditions. Therefore, the present study was carried out with the DEM simulation on the basis of the experiments performed in an indoor soil bin. Based on these situations, the DEM models for the interaction of soil and rotary blade and the interaction of straw, soil, and rotary blade were established. Secondly, the indoor soil bin experiments were conducted. Blade torques at every moment were used to study torque requirement in simulation, and a torque sensor（LKN207） was installed between the output shaft of motor and the rotor of blade through chain transmission to measure the torque force at 0.025 s interval. Both simulation and experiment were performed with 4 rotational speeds of blade（77, 100, 123, and 146 r/min）, the constant forward speed of 0.222 m/s and the depth of 100 mm under 2 soil conditions（with and without straw covered）. It was

关 键 词：农业机械 扭矩 秸秆 土壤 力 旋耕刀 离散单元法 

分 类 号：S222.3[农业科学—农业机械化工程]