| Deep loosening is one of the key technologies of conservation tillage,and the tillage conditions of deep pine gradually change from stubble-free soil to agricultural soil covered with a large amount of straw residue.In order to investigate the interaction law between strawstubble covered soil and winged subsoiler,this paper establishes a stubble covered soil-winged subsoiler interaction simulation model based on the discrete element method,combines the simulation of deep pine operation process and field test to explore the interaction relationship between winged subsoiler and straw-stubble covered soil,and optimizes the key installation parameters of winged subsoiler to provide theoretical basis and technical reference for the design of winged subsoiler.The main research contents and conclusions are as follows:(1)Construct a stubble-covered soil-winged subsoiler interaction simulation model based on the discrete element method.The contact parameters between straw and soil were calibrated by combining the rest angle test and Box-Behnken design method,and the second-order regression model between the rest angle and the three parameters of recovery coefficient,static friction factor and dynamic friction factor between straw and soil was established and analyzed by ANOVA and response surface analysis;the parameters were optimized by means of DesignExpert software and the optimal combination of parameters was obtained as follows The optimal combination of parameters was optimized with the help of Design-Expert software and the optimal combination of parameters was: straw-soil recovery coefficient 0.24,strawsoil static friction factor 0.42 and straw-soil rolling friction factor 0.48.The simulation model of straw-covered soil-winged subsoiler interaction was established by combining the calibrated parameters and the existing research base.(2)Study on the mechanism of stubble-covered soil-winged subsoiler interaction.Based on the simulation models of stubble-covered soil-winged subsoiler and soil-winged subsoiler,the micro and macro soil disturbance,tillage resistance and straw movement during deep pine with winged subsoiler were compared and analyzed,and the results showed that the longitudinal and lateral disturbance range,vertical lifting height and tillage resistance of soil with stubble were greater than those without stubble;the distance of straw from the center of deep pine shovel had a greater influence on the displacement of straw.The distance of straw from the center of deep loosening shovel had the greatest influence on the horizontal lateral movement of straw displacement;the forward direction displacement of straw increased with the increase of straw angle.The error of straw displacement between simulation and field test is small and the change trend is the same,which indicates that the accuracy of the model is good.(3)Simulation and field test for optimization of key installation parameters of deep pine shovel wing shovel.Using a combination of simulation and field test,the orthogonal test was applied to investigate the effects of key installation parameters of wing shovel on soil disturbance,horizontal tillage resistance and tillage efficiency of deep pine shovel.Only the upper tilt angle had a significant effect on the amount of straw accumulation before the shovel;considering the variation characteristics of soil disturbance area,horizontal resistance,straw accumulation before the shovel and tillage efficiency,the wing shovel installation height h of 95 mm,installation angle β of 5° and upper tilt angle φ of 0° were the relatively better combinations of wing shovel installation parameters.The simulation is consistent with the field test and the error is small,so the discrete element model can simulate the deep pine operation process more accurately. |
