基于离散元深松土壤模型的折线破土刃深松铲研究

Research on Polyline Soil-breaking Blade Subsoiler Based on Subsoiling Soil Model Using Discrete Element Method

针对目前华北平原壤土区应用的深松铲作业阻力大、能耗高、平整度差、深松后形成的缝隙过大不利于保墒等问题,基于耕作层、犁底层和心土层土层厚度及土壤物理性质不同,设计了一种有效减阻降耗的折线破土刃深松铲。运用离散元法建立深松土壤模型,设定土壤颗粒接触模型,测定耕作层、犁底层和心土层3层土壤颗粒虚拟仿真参数。应用EDEM软件进行深松铲性能虚拟仿真,检验了破土刃切削刃角θ与滑切角φ最优效果。相比圆弧形深松铲,折线破土刃深松铲对土壤颗粒冲击较小,降低了土层扰动量,降低了牵引阻力,地表平整度与沟槽宽度均明显优于圆弧形深松铲;田间试验结果表明,折线破土刃深松铲有效降低了犁底层的容重和紧实度,比圆弧形深松铲作业阻力减少了11.52%,作业稳定性、可靠性较好。田间试验与仿真试验对比结果证明离散元三层深松土壤模型基本满足深松铲性能试验。

According to the existing problems of subsoilers applied in loam soil area in North-China Plain, such as high working resistance, high fuel consumption, poor surface flatness and poor soil moisture conservation due to the formation of crack after subsoiling, a polyline soil-breaking blade subsoiler which could effectively reduce working resistance and fuel consumption was designed based on the difference of soil layer thickness and physical properties among plough layer, plow pan layer and subsoil layer. Discrete element method（DEM） was used to establish soil model, the soil particle contact model was set, and virtual simulation parameters of different soil particles in plough layer, plow pan layer and subsoil layer were measured. A virtual simulation experiment on subsoiler performance was conducted using EDEM. As shown in the result, minimum working resistance was detected when the rake angle （θ） of soil-breaking blade was ranged from 40°-45°; minimum power dissipation was obtained when the corresponding shearing angle （φ） to the higher, middle and lower parts of soil-breaking blade were 31°, 36°, 33°, respectively; when comparing with circular arc subsoiler, polyline soil-breaking blade subsoiler resulted in less impact on soil particles, reduced soil disturbance, decreased tractive resistance, significantly improved surface flatness and groove width. The field test indicated that the polyline soil- breaking blade subsoiler effectively decreased soil bulk density and compactness of plow pan layer, hence the working resistance was reduced by 11.52% with better working stability and reliability with comparison to circular arc subsoiler. The rationality and feasibility of three-layer DEM soil model was confirmed through the comparison of field test and virtual simulation experiment, and the model could satisfy the requirement of subsoiler performance experiment.