| As a result of year-round rotation tillage,the tillage layer has become shallow,and plough layer has become hard.Sub-soiling tillage can break the hard plough bottom layer,but at the same time easily forms a "V" shaped tillage layer structure,which results in serious water evaporation of soil surface and insufficient water storage of plough bottom layer.It weakens the effect of sub-soiling.The structure of plough layer after sub-soiling can be improved by installing the shovel wings on the shovel,in this paper,with the help of discrete element method and soil trough test,the parameter optimization and experimental study of deep loosening shovel blade are carried out.The research contents and conclusions are as follows:1.Based on the measurement and analysis of soil physical and mechanical parameters in Guanzhong area,a two-layer discrete element soil tillage model was established.The process and parameters of the model could be used for reference for the later establishment of soil discrete element model in other area.The design parameters of the shovel wing were selected,Virtual assembly of shovel wings with Pro/E was completed and the boundary model was established.The parameters of the simulation were set up and the establishment of the simulation model was completed.2.Discrete element simulation analysis.The simulation test was carried out in 81 groups according to the complete test of 4 factors and 3 levels of the shovel wings.By using the established discrete element tillage model,the shallow,medium and deep structures of the soil model are set up.On the basis of three evaluation indexes of ridge height,ratio of the sub-soiling,and ridge width,the mechanism of sub-soiling tillage was comprehensively analyzed.The results showed that the average force of particles was deep layer > middle layer > shallow layer,and when the included angle of shovel wing was 120 °,The effect on ridge height is the least,and the ridge width is the biggest.When the dip angle of shovel wings inclination is 45 °,the influence of shovel wing on ridge height is the least,and the influence on ridge width is the biggest.3.Significance analysis.The significant influence of parameters of shovel wings on the structure of tilling layer was analyzed by SPSS.The output results of Type ? showed that the significance of the angle between the spade wing and the angle of inclination of the shovel wings on the ratio of tillage and plough was 0.001,0.000,0.549,0.730,respectively,which indicated that the influence of the length of the shovel and the height of the shovel wings on the ratio of tillage disturbance layer and plough disturbance layer was significant,and the degree of influence of different factors on the ratio was as follows: the height of the shovel wings > the length of the shovel wings > dip angle of the shovel wings > the included angle of shovel wings4.The comparison and analysis of soil test and simulation test showed that the ridge height and ridge width increased with the increase of the height of the spade wing at different height of the spade wing,and the results showed that the height of the shovel wings increased with the increase of the height of the spade wing.The ridge height and width increased with the length of the spade wing,and the ratio of tillage and plough increased with the height of the shovel wings.The optimum parameters were as follows: the length of the shovel wings was 15 cm,the height of the shovel wings was 7.5 cm,the included angle of the shovel wings is 120 °,and the dip angle of shovel wings was 45 °.That is to say,under this condition,the ratio of tillage disturbance layer and plough disturbance layer was the smallest and the structure of the soil layer after sub-soiling was the most reasonable. |
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