摘要
履带式行走机构因具有较小的接地压力而被逐渐应用在大型农业车辆上,以减小对土壤的压实。然而由于履带下应力分布的不均匀,导致农业车辆对土壤的最大应力并未有效减小,对土壤较长的压力作用时间反而增加了土壤被压实的风险。应力分布的不均匀还会造成履带沉陷量的增大,降低车辆在软土地面的通过性能。为了研究履带式行走机构压实作用下土壤内的应力分布规律以及如何提高应力分布的均匀性,以缓解履带车辆对土壤压实作用、提高履带车辆软地通过能力,该文采用侧断面水平钻孔埋设压力传感器的方法,测得了履带式行走机构压实作用下履带中心线横截面内0.35 m深度土壤内沿履带长度方向上的垂直及水平应力分布;同时研究了履带张紧力大小对应力分布均匀性的影响。结果表明,履带式行走机构下的垂直应力在各负重轮的轴线处呈现一个应力峰值;水平应力在各负重轮轴线的前、后方分别呈现一个应力峰值,且最小应力在轴线处。各负重轮下的应力峰值大小不同。最大垂直应力出现在履带式行走机构后端的导向轮处;最大水平应力出现在后支重轮与导向轮之间。适当减小履带张紧力能够提高垂直及水平应力分布的均匀性。履带张紧力由1.8×10~4k Pa减小至1.6×10~4k Pa时,履带下的最大垂直及水平应力分别减小了约37.3%和21.7%;平均最大垂直及水平应力分别减小了约26.4%和20.4%。研究结果可为履带式行走机构结构的优化提供理论依据,以期提高履带下应力分布的均匀性。
Tracked undercarriage is considered as a technical solution to reduce the soil compaction as compared to the tire due to its large contact area between track and soil.However,the interaction between track and soil is complex,resulting in uneven distributed stress at track/soil interface.Uneven distributed stress may reduce the ability that track decreases the soil compaction and will also lead to the increases of track sinkage depth,which may reduce the vehicle's traffic-ability.Therefore,we can better understanding of the soil compaction process with the help of investigating the distribution of soil stress beneath the tracked undercarriage.The objectives of this study were to estimate the distribution of soil vertical and horizontal stresses under the tracked undercarriage in the track length direction,and to investigate the effect of track tensions on the distribution of soil stress.The test was conducted on the sandy loam soil and combine harvester equipped with rubber tracks was used in the test.The rubber tracked undercarriage system is comprised of a front wheel and a rear wheel with two support wheels.During measurement,the harvester was unloaded and without its header.The soil stress was measured by embedding the pressure sensors under the centerline of the track at depth of 0.35m.In total four pressure sensors were installed:two sensors for vertical stress,and two sensors for horizontal stress(piston facing the vehicle’s driving direction).A laser position sensor fixed on the ground was employed to track the positions of the axle of track wheels.Three repeated measurements were performed with different track tensions(i.e.1.6×104,1.7×104,and 1.8×104 kPa)at same traffic speed.The results showed that the measured vertical stress presented three peak points along the track length,with two peaks beneath each axle of track drive wheel and guide wheel,and one peak between two support wheels.The horizontal stress presented two peaks before and after each wheel axle,with the minimum stress on the axle.Moreo
作者
丁肇
李耀明
任利东
唐忠
Ding zhao;Li Yaoming;Ren Lidong;Tang Zhong(Key Laboratory of Modern Agricultural Equipment and Technology,Ministry of Education,Jiangsu University,Zhenjiang 212013,China;Department of Environment,Ghent University,Ghent,9000,Belgium)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2020年第9期52-58,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发项目(2016YFD0702004)
江苏省自然科学基金面上项目(BK20170553)
江苏省普通高校研究生科研创新计划项目(KYLX15_1047)
江苏高校优势学科建设工程(三期)资助项目。
关键词
农业机械
应力
行走机构
分布均匀性
履带
土壤压实
agricultural machinery
stress
undercarriage
distribution uniformity
track
soil compaction
